HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
INTEGUMENTARY SYSTEM
Integumentary System – consists of skin, its
accessory structures such as hair and sweat glands, and
the subcutaneous tissue below the skin.
Skin – primary organ of the integumentary system;
made of several layers of different tissue types and is
considered an organ.
Pacinian corpuscle (lamellated corpuscle) –
receptors that response to vibration.
Merkel cells – scattered in the stratum basale,
also touch receptors.
3. Thermoregulation – integumentary system
helps regulate body temperature through its
tight association with the sympathetic nervous
system, the division of the nervous system
involved in our fight-or-flight responses.
Sympathetic nervous system – continuously
monitoring body temperature and initiating
appropriate motor responses.
Frostbite – a condition which the temperature
of the skin drops too much (such as
environmental temperatures below freezing),
the conservation of body core heat can result
in the skin actually freezing.
4. Vitamin D Synthesis – epidermal layer of
human skin synthesizes vitamin D when
exposed to UV radiation.
Functions of the Integumentary System:
• Protection
• Sensory Function
• Thermoregulation
• Vitamin D Synthesis
1. Protection – skin protects the rest of the body
from the basic elements of nature such as
wind, water, and UV sunlight. It acts as a
protective barrier against water loss, due to the
presence of layers of keratin and glycolipids in
the stratum corneum. It also is the first line of
defense against abrasive activity due to contact
with grit, microbes, or harmful chemicals.
Dermicidin – an antimicrobial peptide,
component of sweat excreted from sweat
glands that deters microbes from overcolonizing the skin surface which has
antibiotic properties.
2. Sensory Function – skin, and especially the
hairs projecting from hair follicles in the skin,
can sense changes in the environment. The
skin acts as a sense organ because the
epidermis, dermis, and hypodermis contain
specialized sensory nerve structures that detect
touch, surface temperature, and pain.
Meissner corpuscle (tactile corpuscle) –
receptors that response to light touch.
Cholecalciferol – a form of vitamin D3
synthesized from a derivative of the steroid
cholesterol in the skin in the presence of
sunlight.
The liver converts cholecalciferol to calcidiol,
which is then converted to calcitriol (the active
chemical form of the vitamin) in the kidneys.
Components of the Integumentary System:
• Skin and its layers:
o Epidermis
o Dermis
o Hypodermis or Subcutaneous Tissue.
• Skin Pigmentation or Color
• Accessory Structures/Appendages of the Skin:
o Hair
o Nails
o Sweat glands
o Sebaceous glands.
Skin – composed of two main layers: epidermis and
dermis. Beneath the dermis lies the hypodermis.
Epidermis – composed of keratinized, stratified
squamous epithelium. It does not have any blood
vessels within it (avascular).
Keratinocyte – a cell that manufactures and stores the
protein keratin.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Keratin – an intracellular fibrous protein that gives
hair, nails, and skin their hardness and water-resistant
properties.
Sublayers of Epidermis:
• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum
1. Stratum Basale – (also called the stratum
germinativum) is the deepest epidermal layer
and attaches the epidermis to the basal lamina,
below which lie the layers of the dermis. The
cells in the stratum basale bond to the dermis
via intertwining collagen fibers referred to as
the basement membrane. A single layer of
cells primarily made of basal cells.
Dermal papilla (plural = dermal papillae) – a
finger-like projection or fold found in the
superficial portion of the dermis. It increases
the strength of the connection between the
epidermis and dermis; the greater the folding,
the stronger the connections made.
3. Stratum Granulosum – has a grainy
appearance due to further changes to the
keratinocytes as they are pushed from the
stratum spinosum. It has a grainy appearance
due to further changes to the keratinocytes as
they are pushed from the stratum spinosum.
4. Stratum Lucidum – a smooth, seemingly
translucent layer of the epidermis located just
above the stratum granulosum and below the
stratum corneum.
Eleidin – a clear protein rich in lipids, derived
from keratohyalin, which gives these cells
their transparent appearance and provides a
barrier to water.
5. Stratum Corneum – the most superficial
layer of the epidermis and is the layer exposed
to the outside environment. The increased
keratinization (also called cornification) of the
cells in this layer gives it its name.
Microdermabrasion – a cosmetic procedure
which help remove some of the dry, upper
layer and aim to keep the skin looking “fresh”
and healthy.
Basal cell – a cuboidal-shaped stem cell that is
a precursor of the keratinocytes of the
epidermis.
Two other cell types are found dispersed
among the basal cells in the stratum basale:
➢ Merkel cell – which functions as a
receptor and is responsible for
stimulating sensory nerves that the
brain perceives as touch. These cells
are especially abundant on the
surfaces of the hands and feet.
➢ Melanocyte – a cell that produces the
pigment melanin.
2. Stratum Spinosum – spiny in appearance due
to the protruding cell processes that join the
cells via a structure called a desmosome. The
desmosomes interlock with each other and
strengthen the bond between the cells. It is
interesting to note that the “spiny” nature of
this layer is an artifact of the staining process.
Langerhans cell – a type of dendritic cell that
is interspersed among the keratinocytes of this
layer, which functions as a macrophage by
engulfing bacteria, foreign particles, and
damaged cells that occur in this layer.
Dermis – might be considered the “core” of the
integumentary system. It contains blood and lymph
vessels, nerves, and other structures, such as hair
follicles and sweat glands. It is made of two layers of
connective tissue that compose an interconnected mesh
of elastin and collagenous fibers, produced by
fibroblasts.
Sublayers of Dermis:
• Papillary Layer
• Reticular Layer
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
1. Papillary layer – made of loose, areolar
connective tissue, which means the collagen
and elastin fibers of this layer form a loose
mesh.
UV Ray Exposure or Tanning – causes melanin to be
manufactured and built up in keratinocytes, as sun
exposure stimulates keratinocytes to secrete chemicals
that stimulate melanocytes.
Fibroblasts – a small number of fat cells
(adipocytes).
Folic acid – a nutrient necessary for our health and
well-being.
Phagocytes – defensive cells that help fight
bacteria or other infections that have breached
the skin.
Moles – larger masses of melanocytes, and although
most are benign, they should be monitored for changes
that might indicate the presence of cancer.
Meissner corpuscles – touch receptors
Accessory Structures of the Skin/Skin Appendages
– include hair, nails, sweat glands, and sebaceous
glands. These structures embryologically originate
from the epidermis and can extend down through the
dermis into the hypodermis.
2. Reticular Layer – thicker layer, composed of
dense, irregular connective tissue underlying
the papillary layer. This layer is well
vascularized and has a rich sensory and
sympathetic nerve supply. The reticular layer
appears reticulated (netlike) due to a tight
meshwork of fibers.
Elastin fibers – provide some elasticity to the
skin, enabling movement.
Collagen fibers – provide structure and tensile
strength, with strands of collagen extending
into both the papillary layer and the
hypodermis.
Hypodermis – (also called the subcutaneous layer or
superficial fascia) is a layer directly below the dermis
and serves to connect the skin to the underlying fascia
(fibrous tissue) of the bones and muscles. It consists of
well-vascularized, loose, areolar connective tissue and
adipose tissue, which functions as a mode of fat
storage and provides insulation and cushioning for the
integument.
Skin Pigmentation or Skin Color – influenced by a
number of pigments, including melanin, carotene, and
hemoglobin.
Melanocytes – cells that produce melanin which are
found scattered throughout the stratum basale of the
epidermis.
Melanosome – a cellular vesicle that transfers melanin
into the keratinocytes.
Two Primary Forms of Melanin:
• Eumelanin – exists as black and brown.
• Pheomelanin – provides a red color.
Dark-skinned individuals – produce more melanin
than those with pale skin.
Hair – a keratinous filament growing out of the
epidermis. It is primarily made of dead, keratinized
cells.
Hair follicle – an epidermal penetration of the dermis
where strands of hair originate.
Hair shaft – the part of the hair not anchored to the
follicle, and much of this is exposed at the skin’s
surface.
Hair root – lies below the surface of the skin where
the rest of the hair is anchored in the follicle.
Hair matrix – a layer of mitotically active basal cells.
Hair bulb – surrounds the hair papilla, which is made
of connective tissue and contains blood capillaries and
nerve endings from the dermis.
Medulla – forms the central core of the hair.
Cortex – a layer of compressed, keratinized cells.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Cuticle – an outer layer of hair which very hard,
keratinized cells.
Hair growth – a process in which begins with the
production of keratinocytes by the basal cells of the
hair bulb.
Keratinization – completed as the cells are pushed to
the skin surface to form the shaft of hair that is
externally visible.
Electrolysis and Yanking – processes which both
attempt to destroy the hair bulb so hair cannot grow.
Three Concentric Layers of Cells in the Wall of
Hair Follicle:
• Internal root sheath – cells surround the root
of the growing hair and extend just up to the
hair shaft. They are derived from the basal
cells of the hair matrix.
• External root sheath – an extension of the
epidermis, encloses the hair root. It is made of
basal cells at the base of the hair root and
tends to be more keratinous in the upper
regions.
• Glassy membrane – a thick, clear connective
tissue sheath covering the hair root, connecting
it to the tissue of the dermis.
Three Phases of Hair Growth:
• Anagen phase – cells divide rapidly at the
root of the hair, pushing the hair shaft up and
out. The length of this phase is measured in
years, typically from 2 to 7 years.
• Catagen phase – lasts only 2 to 3 weeks, and
marks a transition from the hair follicle’s
active growth.
• Telogen phase – the hair follicle is at rest and
no new growth occurs. At the end of this
phase, which lasts about 2 to 4 months,
another anagen phase begins. The basal cells
in the hair matrix then produce a new hair
follicle, which pushes the old hair out as the
growth cycle repeats itself.
Hair Color – similar to the skin, hair gets its color
from the pigment melanin, produced by melanocytes
in the hair papilla.
Nail bed – a specialized structure of the epidermis that
is found at the tips of our fingers and toes.
Nail body – formed on the nail bed, and protects the
tips of our fingers and toes as they are the farthest
extremities and the parts of the body that experience
the maximum mechanical stress.
Nail root – has a matrix of proliferating cells from the
stratum basale that enables the nail to grow
continuously.
Eponychium – nail cuticle which is formed by the
meet of nail fold and the proximal end of the nail
body.
Lunula – (the “little moon”), a thick layer of
epithelium over the nail matrix that forms a crescentshaped region.
Hyponychium – area beneath the free edge of the nail,
furthest from the cuticle. It consists of a thickened
layer of stratum corneum.
Sweat glands – also called sudoriferous glands,
produce sweat to cool the body When the body
becomes warm.
Merocrine glands – sweat glands that develop from
epidermal projections into the dermis; that is, the
secretions are excreted by exocytosis through a duct
without affecting the cells of the gland.
Two Types of Sweat Glands:
• Eccrine sweat gland – a type of gland that
produces a hypotonic sweat for
thermoregulation. These glands are found all
over the skin’s surface, but are especially
abundant on the palms of the hand, the soles of
the feet, and the forehead. They are coiled
glands lying deep in the dermis, with the duct
rising up to a pore on the skin surface, where
the sweat is released.
• Apocrine sweat gland – usually associated
with hair follicles in densely hairy areas, such
as armpits and genital regions. They are larger
than eccrine sweat glands and lie deeper in the
dermis, sometimes even reaching the
hypodermis, with the duct normally emptying
into the hair follicle.
Sebaceous gland – a type of oil gland that is found all
over the body and helps to lubricate and waterproof the
skin and hair.
Sebum – a mixture of lipids, generated and excreted
by sebaceous glands onto the skin surface, thereby
naturally lubricating the dry and dead layer of
keratinized cells of the stratum corneum, keeping it
pliable.
Skin disorders – a disease affecting the skin.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Five Common Skin Disorders:
1. Eczema - an allergic reaction that manifests as
dry, itchy patches of skin that resemble rashes.
It may be accompanied by swelling of the
skin, flaking, and in severe cases, bleeding.
Many who suffer from eczema have antibodies
against dust mites in their blood, but the link
between eczema and allergy to dust mites has
not been proven. Symptoms are usually
managed with moisturizers, corticosteroid
creams, and immunosuppressants.
2. Psoriasis – a chronic disorder and an immunemediated disease, which means that your
body’s immune system starts overacting,
causing skin cells to multiply too quickly. This
is why skin in people with the disease is
inflamed and scaly. Symptoms of psoriasis
vary from person to person, but some common
ones are patches of thick, red skin with
silvery-white scales that itch or burn, typically
on the elbows, knees, scalp, trunk, palms, and
soles of the feet. Dry, cracked skin that itches
or bleeds, thick, ridged, pitted nails.
3. Ichthyosis – a skin disorder that leads to dry,
itchy skin that appears scaly, rough, and red. It
can affect only the skin, but some forms of the
disease can affect internal organs as well.
Most people inherit ichthyosis from their
parents through a mutated (changed) gene.
However, some people develop a form of
acquired (nongenetic) ichthyosis from another
medical disorder or certain medications.
While there is currently no cure for ichthyosis,
research is ongoing and treatments are
available to help manage the symptoms.
4. Warts – this is the kind of skin infection
which happens due to HPV or Human
Papillomavirus. It is basically relating to how
you will be suffering from an infection which
includes having rough, skin-colored bumps
which will begin to form on the skin. The
problem is that it can become something very
contagious. While it can happen on any part of
the body but it is more common on feet, face
as well as genitals.
5. Acne – a skin disturbance that typically occurs
on areas of the skin that are rich in sebaceous
glands (face and back). It is most common
along with the onset of puberty due to
associated hormonal changes, but can also
occur in infants and continue into adulthood.
Hormones, such as androgens, stimulate the
release of sebum. An overproduction and
accumulation of sebum along with keratin can
block hair follicles. This plug is initially white.
The sebum, when oxidized by exposure to air,
turns black. Acne results from infection by
acne-causing bacteria (Propionibacterium and
Staphylococcus), which can lead to redness
and potential scarring due to the natural wound
healing process.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
SKELETAL SYSTEM
Skeletal system – consists of bones and joints of the
body and their associated connective tissues, including
cartilage, tendons, and ligaments.
Functions of the Skeletal System:
• Support
• Protection
• Movement
• Storage
• Blood cell production
1. Support – Rigid, strong bone is well suited for
bearing weight and is the major supporting
tissue of the body. Cartilage provides a firm
yet flexible support within certain structures,
such as the nose, external ear, thoracic cage,
and trachea. Ligaments are strong bands of
fibrous connective tissues that attach to bones
and hold them together.
2. Protection – Bone is hard and protects the
organs it surrounds. For example, the skull
encloses and protects the brain, and the
vertebrae surround the spinal cord. The rib
cage protects the heart, lungs, and other organs
of the thorax.
Bone Development and Growth
• Skeletal growth begins about 6 weeks after
fertilization, when the embryo is about 12 mm
(0.5 in.) long.
• Bone growth continues through adolescence,
and typically portions of the skeleton continue
growing until roughly age 25.
• During development, cartilage or other
connective tissues are replaced by bone. The
process of replacing other tissues with bone is
called ossification.
Two major forms of ossification:
• Intramembranous Ossification
• Endochondral Ossification
Intramembranous Ossification
➢ During intramembranous ossification, compact
and spongy bone develops directly from sheets
of mesenchymal (undifferentiated) connective
tissue.
➢ The flat bones of the face, most of the cranial
bones, and the clavicles (collarbones) are
formed via intramembranous ossification.
➢ Intramembranous ossification follows four
steps.
3. Movement – Skeletal muscles attach to bones
by tendons, which are strong bands of
connective tissues. Contraction of the skeletal
muscles moves the bones, producing body
movements. Joints, which are formed where
two or more bones come together, allow
movement between bones. Smooth cartilage
covers the bones to move freely. Ligaments
allow some movements between bones but
prevent excessive movements.
4. Storage – Some minerals in the blood are
taken into bone and stored. Should blood
levels of these minerals decrease, the minerals
are released from bone into blood. The
principal minerals stored are calcium and
phosphorus. Fat (adipose tissue) is also stored
within bone cavities. If needed, the fats are
released into the blood and used by other
tissues as a source of energy.
5. Blood cell production – Many bones contain
cavities filled with bone marrow that gives rise
to blood cells and platelets.
Endochondral Ossification
➢ In endochondral ossification, bone develops
by replacing hyaline cartilage.
➢ Cartilage serves as a template to be completely
replaced by new bone.
➢ Endochondral ossification takes much longer
than intramembranous ossification.
➢ Bones at the base of the skull and long bones
form via endochondral ossification.
Endochondral ossification follows five steps:
1. Mesenchymal cells differentiate into
chondrocytes.
2. The cartilage model of the future bony
skeleton and the perichondrium form.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
3. Capillaries penetrate cartilage.
4. Secondary ossification centers develop.
5. Cartilage remains at the epiphyseal (growth)
plate and at the joint surface as articular
cartilage.
Factors that Affect Bone Growth and
Maintenance:
Bone Structure
Two areas of endochondral bone retain
cartilage after ossification:
1. Articular cartilage – surrounds the epiphysis
of joints.
2. Epiphyseal plates – retain cartilage for bone
growth.
Bone (Osseous tissue) – a hard, dense connective
tissue that forms most of the adult skeleton, the
support structure of the body. In the areas of the
skeleton where bones move (for example, the ribcage
and joints), cartilage, a semi-rigid form of connective
tissue, provides flexibility and smooth surfaces for
movement.
➢ Bone contains a relatively small number of
cells entrenched in a matrix of collagen fibers
that provide a surface for inorganic salt
crystals to adhere.
➢ These salt crystals form when calcium
phosphate and calcium carbonate combine to
create hydroxyapatite, which incorporates
other inorganic salts like magnesium
hydroxide, fluoride, and sulfate as it
crystallizes, or calcifies, on the collagen fibers.
➢ The hydroxyapatite crystals give bones their
hardness and strength, while the collagen
fibers give them flexibility so that they are not
brittle.
➢ Although bone cells compose a small amount
of the bone volume, they are crucial to the
function of bones.
Four types of cells are found within bone tissue:
1. Osteoblasts
2. Osteocytes
3. Osteogenic cells
4. Osteoclasts
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Spongy (Cancellous) Bone
➢ Like compact bone, spongy bone, also known
as cancellous bone, contains osteocytes housed
in lacunae, but they are not arranged in
concentric circles. Instead, the lacunae and
osteocytes are found in a lattice-like network
of matrix spikes called trabeculae (singular =
trabecula).
➢ The trabeculae may appear to be a random
network, but each trabecula forms along lines
of stress to provide strength to the bone. The
spaces of the trabeculated network provide
balance to the dense and heavy compact bone
by making bones lighter so that muscles can
move them more easily. In addition, the spaces
in some spongy bones contain red marrow,
protected by the trabeculae, where
hematopoiesis occurs.
COMPACT AND SPONGY BONE
➢ Most bones contain compact and spongy
osseous tissue, but their distribution and
concentration vary based on the bone’s overall
function. Compact bone is dense so that it can
withstand compressive forces, while spongy
(cancellous) bone has open spaces and
supports shifts in weight distribution
Compact Bone
➢ Compact bone is the denser, stronger of the
two types of bone tissue.
➢ It can be found under the periosteum and in
the diaphysis of long bones, where it provides
support and protection.
➢ The microscopic structural unit of compact
bone is called an osteon, or Haversian system.
➢ Each osteon is composed of concentric rings
of calcified matrix called lamellae (singular =
lamella).
➢ The osteocytes are located inside spaces called
lacunae (singular = lacuna), found at the
borders of adjacent lamellae.
Gross Structure of Long Bone
➢ A long bone has two parts: the diaphysis and
the epiphysis.
1. Diaphysis – tubular shaft that runs between
the proximal and distal ends of the bone. The
hollow region in the diaphysis is called the
medullary cavity, which is filled with yellow
marrow. The walls of the diaphysis are
composed of dense and hard compact bone.
2. Epiphysis – The wider section at each end of
the bone (plural = epiphyses), which is filled
with spongy bone.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
➢ Each bone in the human skeleton has not only
distinctive shape but also characteristic
external and internal features.
➢ For example, elevations or projections from
where tendons and ligaments attach and where
adjacent bones articulate at joints. Depressions
and openings indicate sites where blood
vessels and nerves run alongside or penetrate
the bone. These landmarks are called bone
markings, or surface features.
Classification of Bones
➢ The 206 bones that compose the adult skeleton
are divided into five categories based on their
shapes.
➢ Their shapes and their functions are related
such that each categorical shape of bone has a
distinct function.
1. Long Bones
2. Short Bones
3. Flat Bones
4. Irregular Bones
5. Sesamoid Bones
Division of the Skeletal System
1. Axial skeletal
• skull
• vertebral column
• thoracic cage
2. Appendicular skeleton
• pectoral and pelvic girdles,
• the limb bones
• the bones of the hands and feet
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
AXIAL SKELETAL
➢ The axial skeleton forms the vertical, central
axis of the body and includes all bones of the
head, neck, chest, and back.
➢ It serves to protect the brain, spinal cord, heart,
and lungs. It also serves as the attachment site
for muscles that move the head, neck, and
back, and for muscles that act across the
shoulder and hip joints to move their
corresponding limbs.
➢ The axial skeleton of the adult consists of 80
bones, including the skull, the vertebral
column, and the thoracic cage.
Skull
➢ 22 bones joined together by sutures
➢ 8 sutured bones in cranium
➢ Facial bones: 13 sutured bones, 1 mandible
Sutures – movable joints found only between bones:
1. Coronal
2. Sagittal
3. Lambdoid
4. Squamous
Cranial bones surround cranial cavity
• 8 bones in contact with meninges.
• Frontal, Sphenoid, Occipital, Ethmoid, (2)
Temporal, and (2) Parietal.
Facial bones support teeth & form nasal cavity &
orbit
• 14 bones with no direct contact with brain or
meninges
• (2) Nasal bones, (2) Maxillae, (2) Zygomatic,
(2) Lacrimal, (2) Palatine, (2) Inferior nasal
concha, (1) Vomer, (1) Mandible
Sinuses
➢ Cranial bones containing sinuses:
• Frontal, sphenoid, ethmoid, maxillae.
➢ Paranasal Sinuses
• Hollow portions of bones surrounding
the nasal cavity.
➢ Sinusitis
• Occurs when membranes become
inflamed.
• May cause pain by the buildup of
pressure.
Hyoid bone
➢ U-shaped bone.
➢ The only bone that does not articulate with
another bone.
➢ Support the tongue.
➢ Provide attachment for the tongue muscle,
neck and pharynx muscles.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Mandible
Vertebral column
➢ The vertebral column consists of 24 bones,
each called a vertebra, plus the sacrum and
coccyx.
➢ Vertebrae separated by intervertebral discs
➢ The spine has a normal curvature.
➢ Each vertebrae is given a name according to
its location.
• cervical vertebrae
• 12 thoracic
• 5 lumbar
• 1 sacrum (5 fused)
• 1 coccyx (4 fused)
➢ Process
• Spinous
• Transverse
• articular
➢ Neural arch
• 2 lamina
• 2 pedicles
➢ Body
➢ Disc
Thoracic cage
➢ The thoracic cage includes the 12 pairs of ribs,
and the sternum, the flattened bone of the
anterior chest.
➢ True ribs (1 to 7) are directly attached to the
sternum with hyaline cartilage.
➢ False ribs are ribs 8-10.
➢ Floating ribs are 11-12 and are not attached to
sternum.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
APPENDICULAR SKELETON
➢ The appendicular skeleton includes all bones
of the upper and lower limbs, plus the bones
that attach each limb to the axial skeleton.
➢ There are 126 bones in the appendicular
skeleton of an adult. The bones of the
appendicular skeleton are covered in a
separate chapter.
➢ The appendicular skeleton consists of the
pectoral and pelvic girdles, the limb bones,
and the bones of the hands and feet.
Pectoral Girdles
➢ Attaches upper extremity to the body
➢ consists of the clavicle and the scapula, which
serve to attach the upper limb to the sternum
of the axial skeleton.
Clavicle
➢ The clavicle is the only long bone that lies in a
horizontal position in the body.
➢ Clavicle attaches medially to the sternum and
laterally to the scapula
➢ The clavicle has several important functions:
• anchored by muscles from above, it
serves as a strut that extends laterally
to support the scapula.
• transmits forces acting on the upper
limb to the sternum and axial skeleton
• it serves to protect the underlying
nerves and blood vessels as they pass
between the trunk of the body and the
upper limb.
➢ Clavicle is the most frequently broken bone in
the body.
• S-shaped bone.
• Sternal end is rounded, acromial end is
flattened.
Scapula
➢ The scapula (shoulder blade) lies on the
posterior aspect of the shoulder. It is supported
➢
➢
➢
➢
➢
by the clavicle, which also articulates with the
humerus (arm bone) to form the shoulder joint.
The scapula is a flat, triangular-shaped bone
with a prominent ridge running across its
posterior surface.
The scapula has several important
landmarks:
• the superior border of the scapula
• the medial border of the scapula
• the lateral border of the scapula
Spine of scapula laterally becomes the
acromion process.
Coracoid process anteriorly for muscle
attachment.
The scapula has three depressions, each of
which is called a fossa (plural = fossae):
• supraspinous fossa
• infraspinous fossa
• subscapular fossa
Bones of upper limb
➢ The upper limb is divided into three regions:
• the arm
• the forearm
• the hand
➢ There are 30 bones in each upper limb
➢ The humerus is the single bone of the upper
arm, and the ulna (medially) and the radius
(laterally) are the paired bones of the forearm
➢ Carpus or wrist contain 8 small bones
➢ Hand contains 19 bones:
• 5 metacarpals in the palm
• 14 phalanges in the fingers
Humerus
➢ Long bone that extends from the scapula to the
elbow.
➢ Special features:
• Head
• Greater tubercle and lesser tubercle
• Intertubular groove
• Anatomical next
• Surgical neck
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
•
•
•
•
•
•
Deltoid tuberosity
Capitulum
Trochlea
Epicondyles
Coronoid fossa
Olecranon foassa
Radius
➢ Located on the thumb side of the forearm
➢ A little bit shorter that the ulna
➢ Crosses over the ulna when the hand is turned
so that the palm faces backwards
➢ Special features:
• Head
• Radial tuberosity
• Styloid
Carpal bones
➢ 8 total bones
➢ 2 rows of 4 bones each name the proximal row
first, distal row second.
➢ The carpus is rounded on its proximal surface
where it articulates with the radius and the
fibrocartilaginous disc on the ulnar side.
➢ The distal surface of the carpus articulates
with the metacarpal bones.
Ulna
➢ Second bone in the forearm
➢ Overlaps the end of the humerus posteriorly
➢ Special features:
• Head
• Trochlear notch
• Olecranon process
• Coronoid process
• Styloid process
Metacarpals and Phalanges
➢ Phalanges are bones of the fingers
• Thumb or pollex has proximal &
distal phalanx.
• Fingers have proximal, middle &
distal phalanx.
➢ Metacarpals are bones of the palm.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Pelvis
➢ Composed of 4 bones: right & left hip, sacrum
and coccyx.
➢ Provides a strong and stable support on which
the weight of the body is transferred.
Hip Bone
➢ Acetabulum is the joint socket
➢ Ilium is the superior portion
➢ Pubis is anterior portion
➢ Ischium is posterolateral portion
Femur
➢ Longest and heaviest bone in the body
➢ It's around 18 inches long
➢ At the upper end it articulates with the hip
bone to create the hip joint.
➢ At the lower end it articulates with the patella
and tibia.
➢ The femur conducts body weight from
the hip bone to the tibia in standing
position.
Knee
➢ The knee is composed of three bones:
• Femur
• Tibia
• Patella
➢ Patella is triangular sesamoid bone
• Sesamoid are found in tendons or
ligaments, sesame seed shaped
➢ Tibia is thick, strong weight-bearing bone on
medial side of leg
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Fibula
➢ Slender lateral strut that helps stabilize the
ankle
➢ Does not bear any of the body's weight
➢ Head is proximal end
➢ Lateral malleolus is distal expansion
➢ Joined to tibia by interosseous membrane
Synarthrosis – An immobile or nearly immobile joint
is called a synarthrosis. The immobile nature of these
joints provides for a strong union between the
articulating bones.
Amphiarthrosis – An amphiarthrosis is a joint that
has limited mobility.
Diarthrosis – A freely mobile joint is classified as a
diarthrosis. These types of joints include all synovial
joints of the body, which provide the majority of body
movements.
Fibrous Joints
➢ At a fibrous joint, the adjacent bones are
directly connected to each other by fibrous
connective tissue, and thus the bones do not
have a joint cavity between them.
• Suture
• Syndesmosis
• Gomphosis
Foot
➢ The foot consists of 26 bones; 7 tarsals, 5
metatarsal and 14 phalanges
• Seven tarsal bones constitute the ankle
and share the weight associated with
walking.
• Five metatarsal bones are contained in
the foot.
• 14 phalanges in the toes in each foot.
Joints
➢ A joint, also called an articulation, is any
place where adjacent bones or bone and
cartilage come together (articulate with each
other) to form a connection.
➢ joints are designed for stability and provide for
little or no movement
➢ Joints are classified both structurally and
functionally:
• Structural classifications of joints
take into account whether the adjacent
bones are strongly anchored to each
other by fibrous connective tissue or
cartilage, or whether the adjacent
bones articulate with each other within
a fluid-filled space called a joint
cavity.
• Functional classifications describe
the degree of movement available
between the bones, ranging from
immobile, to slightly mobile, to freely
moveable joints.
Cartilaginous Joints
➢ As the name indicates, at a cartilaginous joint,
the adjacent bones are united by cartilage, a
tough but flexible type of connective tissue.
These types of joints lack a joint cavity and
involve bones that are joined together by either
hyaline cartilage or fibrocartilage.
• Synchondrosis
• Symphysis
Synovial Joints
➢ Synovial joints are the most common type of
joint in the body.
➢ A key structural characteristic for a synovial
joint that is not seen at fibrous or cartilaginous
joints is the presence of a joint cavity. The
walls of this space are formed by the articular
capsule, a fibrous connective tissue structure
that is attached to each bone just outside the
area of the bone’s articulating surface.
➢ Synovial joints are subdivided based on the
shapes of the articulating surfaces of the bones
that form each joint.
➢ The six types of synovial joints are pivot,
hinge, condyloid, saddle, plane, and ball-and
socket-joints.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
The six types of synovial:
1. Pivot Joint – allow for rotation around an
axis, such as between the first and second
cervical vertebrae, which allows for side-toside rotation of the head.
2. Hinge Joint – hinge joint of the elbow works
like a door hinge.
3. Condyloid Joint – The articulation between
the trapezium carpal bone and the first
metacarpal bone at the base of the thumb is a
saddle joint.
4. Saddle Joint – Plane joints, such as those
between the tarsal bones of the foot, allow for
limited gliding movements between bones.
5. Plane Joint - The radiocarpal joint of the wrist
is a condyloid joint.
6. Ball-and-Socket Joint – hip and shoulder
joints are the only ball-and-socket joints of the
body.
Disorders Related to the Bones and Joints
1. Paget’s Disease
➢ It is a disorder of the bone remodeling
process that begins with overactive
osteoclasts.
➢ While some people with Paget’s
disease have no symptoms, others
experience pain, bone fractures, and
bone deformities
➢ Bones of the pelvis, skull, spine, and
legs are the most commonly affected.
When occurring in the skull, Paget’s
disease can cause headaches and
hearing loss
➢ Normal leg bones are relatively
straight, but those affected by Paget’s
disease are porous and curved.
2. Osteogenesis imperfecta (OI)
➢ Osteogenesis imperfecta (OI) is a
genetic disease in which bones do not
form properly and therefore are fragile
and break easily.
➢ It is also called brittle bone disease.
➢ The disease is present from birth and
affects a person throughout life.
➢ The genetic mutation that causes OI
affects the body’s production of
collagen, one of the critical
components of bone matrix. The
severity of the disease can range from
mild to severe.
➢ people with OI may also experience
fragile skin, weak muscles, loose
joints, easy bruising, frequent
nosebleeds, brittle teeth, blue sclera,
and hearing loss.
3. Osteoporosis
➢ Osteoporosis is a disease characterized
by a decrease in bone mass that occurs
when the rate of bone resorption
exceeds the rate of bone formation, a
common occurrence as the body ages
➢ While osteoporosis can involve any
bone, it most commonly affects the
proximal ends of the femur, vertebrae,
and wrist. As a result of the loss of
bone density.
➢ While osteoporosis can involve any
bone, it most commonly affects the
proximal ends of the femur, vertebrae,
and wrist. As a result of the loss of
bone density.
➢ osteoporosis is more common in
women than in men
➢ Anyone with a family history of
osteoporosis has a greater risk of
developing the disease, so the best
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
treatment is prevention, which should
start with a childhood diet that
includes adequate intake of calcium
and vitamin D and a lifestyle that
includes weight-bearing exercise.
4. Fractures of Upper Limb Bones
➢ Due to our constant use of the hands
and the rest of our upper limbs, an
injury to any of these areas will cause
a significant loss of functional ability.
Many fractures result from a hard fall
onto an outstretched hand. The
resulting transmission of force up the
limb may result in a fracture of the
humerus, radius, or scaphoid bones.
These injuries are especially common
in elderly people whose bones are
weakened due to osteoporosis.
5. Bursitis
➢ Bursitis is the inflammation of a bursa
near a joint. This will cause pain,
swelling, or tenderness of the bursa
and surrounding area, and may also
result in joint stiffness. Bursitis is
most commonly associated with the
bursae found at or near the shoulder,
hip, knee, or elbow joints.
6. Giantism
➢ Is a condition of abnormally increased
size that usually involves excessive
endochondral growth at epiphyseal
plates of long bones.
7. Dwarfism
➢ The condition in which a person is
abnormally small, may result from
improper growth in the epiphyseal
plates.
8. Rickets
➢ Rickets is the softening and
weakening of bones in children,
usually because of an extreme and
prolonged vitamin D deficiency.
9. Osteomyelitis
10. Tumors
11. Osteomalacia
12. Arthritis
13. Degenerative Joint Disease
14. Gout
MUSCULAR SYSTEM
Muscular system – composed of specialized cells
called muscle fibers. Their predominant function is
contractibility. Muscles, attached to bones or internal
organs and blood vessels, are responsible for
movement. Nearly all movement in the body is the
result of muscle contraction. The muscular system is
an organ system responsible for providing strength,
keeping up the balance, maintaining posture, allowing
movement, and producing heat. It includes all the
muscle tissues, such as the skeletal muscle tissues,
smooth muscle tissues, and cardiac muscle tissues.
The 3 types of Muscles tissues:
1. Skeletal muscle tissue
2. Smooth muscle tissue
3. Cardiac muscle tissue
Smooth muscle – Fibers are thin and spindle shaped,
no striations, single nuclei, involuntary contracts
slowly.
Cardiac muscle – Cells are branched and appear fused
with one another, has striations. Each cell has a central
nuclei, also involuntary.
Skeletal muscle – Fibers are long and cylindrical, has
many nucle, has striations, has an alternating dark and
light bands. Voluntary
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Functional characteristics of muscle tissue:
1. Excitability – is the ability to respond to a
stimulus, which may be delivered from a
motor neuron or a hormone.
2. Contractility – is the ability of muscle cells to
forcefully shorten.
3. Extensibility – ability of a muscle to extend to
a predetermined endpoint.
4. Elasticity – is the ability to stretch a muscle to
reach its full range of movement without
restriction.
Sliding Filament Mechanism
1. Myosin heads split ATP and become
reoriented and energized.
2. Myosin heads bind to actin forming cross
bridges
3. Myosin heads rotate towards center of the
sarcomere (power stroke)
4. As myosin heads bind ATP, the cross bridges
detach from actin
The Skeletal Muscle Tissue Structure
Contraction and relaxation of skeletal muscle
➢ The termination of muscle contraction is
followed by muscle relaxation, which is a
return of the muscle fibers to their low
tension-generating state. Muscle contractions
can be described based on two variables:
length and tension.
Types of Muscle Contraction
• Isometric Contraction – This type of muscle
contraction happens when your muscle is
actively held at a set length. Instead of
lengthening and shortening as it would during
some activities, you hold it in a position that
requires a specific length once activated. An
example of this type of contraction is carrying
something in your arms in front of you. You
aren’t trying to raise or lower the object but
keep it at a steady position.
• Isotonic contractions – these occur when a
muscle contracts and changes length and there
are two types:
➢ Isotonic concentric contraction –
this involves the muscle shortening.
The origin and insertion of the muscle
move closer together and the muscle
becomes fatter.
➢ Isotonic eccentric contraction – this
involves the muscle lengthening
whilst it is under tension. The origin
and the insertion move further away
from each other. An eccentric
contraction provides the control of a
movement on the downward phase
and it works to resist the force of
gravity.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Muscle Arrangement
1. Antagonistic Muscle – is a muscle that
opposes the action of another. For example,
when the triceps oppose the contraction of the
flexing biceps by relaxing, the triceps would
be regarded as the antagonistic muscle to the
biceps whereas the biceps, the agonist muscle.
➢ Agonist refers to the doer of an action,
Antagonist refers to the opposition to
action.
2. Synergistic muscles – are groups of muscles
that work together to cause the same
movement. The muscle that aids a prime
mover in a movement and helps prevent
rotation, they help to stabilize joints and helps
to cause unwanted movement that could cause
injury. Ex. making a fist possible without
bending the wrist because of synergistic
muscles in the wrist that keeps it stabilized.
Muscle Tone
➢ is the amount of tension (or resistance to
movement) in muscles. Our muscle tone
helps us to hold our bodies upright when
we are sitting and standing. Changes in
muscle tone are what enable us to move.
Muscle tone also contributes to the
control, speed and amount of movement
we can achieve.
➢ Muscle tone depends on a small
percentage of all the motor units
contracting out of phase with one another
at any point in time. Appropriate muscle
tone enables our bodies to quickly respond
to a stretch. For example, if someone took
your arm and quickly straightened your
elbow, your biceps muscle would
automatically respond and contract in
response to protect you from injury.
Energy Sources for Muscle Contraction – Muscle
cells convert chemical energy to mechanical energy.
ATP is the energy source used for this conversion.
1. Creatine Phosphate – Immediate high-energy
source for replenishing the ATP supply. is the
fastest but least efficient method of producing
ATP. 1 ATP molecule is generated for each
CP molecule.
2. Anaerobic Cellular Respiration – is a type of
cellular respiration where respiration takes
place in the absence of oxygen. The process is
also called fermentation.
3. Aerobic Cellular Respiration – is the aerobic
catabolism of nutrients to carbon dioxide,
water, and energy, and involves an electron
transport system in which molecular oxygen is
the final electron acceptor. Most eukaryotes
and prokaryotes use aerobic respiration to
obtain energy from glucose.
➢ The complete process of aerobic
respiration occurs in four different
stages: Glycolysis, Formation of
Acetyl Coenzyme A, Citric Acid
Cycle, and Electron Transport Chain
Effects of Exercise on Muscles
• Exercise also improves blood supply to the
muscles and increases their capacity to use
oxygen. Resistance training prevents the agerelated loss of muscle mass known as
sarcopenia.
• Exercise involves a series of sustained muscle
contractions, of either long or short duration,
depending on the nature of the physical
activity. Effects of exercise on muscles can be
considered short-term or immediate, both
during and shortly after exercise; as well as
long-term, lasting effects.
• Immediate, Short-Term Effects:
1. The effects of exercise on muscles
varies with the type and duration of
the activity. Aerobic exercise is
typical of activities requiring
endurance and sustained muscle
contractions. Such activities rely
mainly on Type I (slow-twitch
muscles) which sustain maximal
contraction for extensive periods of
time. This use of slow-twitch muscles,
and the availability of oxygen,
prevents the build-up of lactic acid,
and typically does not result in
substantial muscle fatigue in the shortterm. Sustained aerobic respiration
tends to shift the metabolic pathways
of muscle to favor the use of fat as the
primary source of ATP, and glycogen
is generally avoided.
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MIDTERM NOTES
2. Anaerobic respiration, typical of
sprinting and weight lifting, prioritizes
the use of Type II (fast-twitch)
muscles fibers for short, high-intensity
contractions. Muscles prioritize the
use of readily-available ATP, glucose
and glycogen for these contractions,
which results in a build-up of lactic
acid. Though traditionally viewed as
the cause of muscle fatigue, recent
research indicates ion shortages,
particularly of calcium, during an
aerobic exercise, causes such muscle
fatigue. However, lactic acid inhibits
further ATP production, indirectly
causing fatigue.
• Long-Term Effects
1. Muscle hypertrophy, or the increase
in muscle mass due to exercise,
particularly weight training, is a
noticeable long-term effect of
exercise. Exercise of specific muscles
can often result in hypertrophy in the
opposite muscles as well, a
phenomenon known as cross
education.
Samples of Muscles in the Body
• Skeletal Muscles of the Hand
•
Skeletal Muscles of the Chest
➢ external intercostals, internal
intercostals, innermost intercostal,
Subcostales, transversus thoracis,
levatores costarum, serratus posterior
inferior, serratus posterior superior,
thoracic diaphragm
Intramuscular injections – are used when other types
of delivery methods aren’t recommended. These
include:
1. oral (swallowed into the stomach)
2. intravenous (injected into the vein)
3. subcutaneous (injected into the fatty tissue
just under the layer of skin)
Sites for Intramuscular Injections:
1. Deltoid muscle of the arm
2. Vastus lateralis muscle of the thigh
3. Ventrogluteal muscle of the hip
4. Dorsogluteal muscles of the buttocks
Abnormalities and Disorders in Skeletal Muscle
Function
1. Tetanus – an infection caused by bacteria
called Clostridium tetani. When the bacteria
invade the body, they produce a poison (toxin)
that causes painful muscle contractions.
Another name for tetanus is “lockjaw”. It often
causes a person's neck and jaw muscles to
lock, making it hard to open the mouth or
swallow.
2. Hypertrophy – is an increase and growth of
muscle cells. Hypertrophy refers to an increase
in muscular size achieved through exercise.
When you work out, if you want to tone or
improve muscle definition, lifting weights is
the most common way to increase
hypertrophy.
3. Atrophy – is reduction in size of cell, organ or
tissue, after attaining its normal mature
growth. In contrast, hypoplasia is the reduction
in size of a cell, organ, or tissue that has not
attained normal maturity. Atrophy is the
general physiological process of reabsorption
and breakdown of tissues, involving apoptosis.
4. Muscle cramps – muscle cramps are sudden,
involuntary contractions that occur in various
muscles. These contractions are often painful
and can affect different muscle groups.
Commonly affected muscles include those in
the back of your lower leg, the back of your
thigh, and the front of your thigh.
5. Muscular Dystrophy – Muscular dystrophy is
a group of conditions that damage and weaken
your muscles over time. This damage and
weakness are due to the lack of a protein
called dystrophin, which is necessary for
typical muscle function. A deficiency of this
protein can cause problems with walking,
swallowing, and muscle coordination, among
other symptoms. Most diagnoses occur in
childhood, although they can occur at any age.
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MIDTERM NOTES
NERVOUS SYSTEM
Nervous system – most complex and highly organized
body system, is the major controlling, regulatory, and
communication system of the body. It is the center of
all mental activity including thought, learning, and
memory.
Structures of the Nervous System
Nervous System has two main parts:
1. Central Nervous System – is made up of the
brain and spinal cord.
2. Peripheral Nervous System – consist of all
nervous tissue outside the Central Nervous
System. Composed of nerves, ganglia, enteric
plexus and sensory receptors.
Central Nervous System
1. Brain
➢ Located in the skull.
➢ Contains about 85 billion neurons
➢ Weighs about 1300 g (almost 3 lbs.)
➢ Consists of 10-50 trillion of neuroglia.
➢ Seat of intelligence, interpreter of senses,
initiator of body movement, and controller
of behavior.
2. Spinal Cord
➢ Connected to the brain via foramen
magnum of the occipital bone and is
encircled by bones in the vertebral column.
➢ Contains about 100 million neurons.
➢ Even more composed of neuroglia.
➢ Contains neural circuits.
➢ Source of thoughts, emotions and
memories.
➢ Sends signals that stimulate muscles to
contract and glands to secrete.
Peripheral Nervous System
1. Nerves
➢ Consist of bundles of hundreds to
thousands of axons
➢ Associated with connective tissue and
blood vessels outside CNS
➢ Cranial nerves – 12 pairs (emerge
from the brain)
➢ Spinal nerves – 31 pairs (emerge from
the brain)
2. Ganglia
➢ Small masses of nervous tissues
➢ Consist of neuron cell bodies
(primarily)
➢ Located outside brain and spinal cord
➢ Closely associated with cranial and
spinal nerves
3. Enteric Plexus
➢ Extensive networks of neurons located
in the walls of gastrointestinal tract
➢ Neurons help to regulate digestive
tract
4. Sensory Receptors
➢ Structure of nervous system that
monitor external and internal changes
➢ Example:
• Touch receptors (skin)
• Photoreceptors (Eye)
• Olfactory receptors (nose)
Functions of the Nervous System
• Sensory function
• Integrative function
• Motor function
Sensory function
➢ Sensory receptors detect internal stimuli
➢ Detect external stimuli
➢ Sensory information is carried to the brain and
spinal cord through cranial and spinal nerves.
Integrative function
➢ Nervous system processes sensory information
by analyzing it and making decision for
appropriate responses
Motor function
➢ Once sensory information is integrated, the
nervous system may elicit an appropriate
motor response by activating effectors
(muscles and glands) through cranial as spinal
nerves
➢ Stimulation of the effectors causes muscle to
contract and glands to secrete
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Organization of the Nervous System
➢ Functions of CNS and PNS correlate with the
differences
➢ Neurons lost the stability to undergo mitotic
division as a result of their specialization
➢ Neuroglia continues to divide throughout an
individual’s lifetime
Neurons
➢ Possess electrical excitability – the ability to
respond to a stimulus and convert it to action
potential.
➢ Tiny neuron propagates impulses over a short
distance within (less than 1 mm) CNS
➢ Others are the longest cells in the body
➢ Nerve impulses travel great distance at speed
ranged from 0.5-130 m/s (1-90 290 mi/hr)
Most neurons have three parts:
1. Cell body – contains nucleus rounded
cytoplasm and typical cellular organelles.
2. Dendrites – receiving or input portion.
3. Axons – propagates nerve impulses toward
another neurons, muscle fiber, or gland cell.
The Nervous Tissue
Nervous tissue is comprised of two types of cells:
• Neurons
• Neuroglia
➢ Forms the complex processing networks
within the brain and spinal cord
➢ Connects all regions of the body to the brain
and spinal cord
➢ Consist of highly specialized cells:
• Capable of reaching great lengths
• Making extremely intricate
connections with other cells
➢ Both neurons and neuroglia differ structurally
depending on its location, either CNS or PNS.
Two types of transport system for material in
neurons:
1. Slow axonal transport – slower system which
moves materials about 1-5 mm per day
2. Fast axonal transport – capable of moving
materials a distance of 200-400 mm per day
• Anterograde (forward)
• Retrograde (backward)
Structural classification of neurons:
1. Multipolar neurons – usually have several
dendrites and one axon. Most neurons in the
bran and the spinal cord are of this type.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
2. Bipolar neurons – have one axon and one
main dendrite. Found in the retina of the eye,
inner ear, and olfactory area of the brain.
2. Motor or efferent neurons – (away from),
convey action potentials away from the CNS
to effectors (muscles and glands) in the PNS
through cranial or spinal nerves
• Motor neurons are multipolar in
structure
3. Unipolar neurons – have dendrites and one
axon that are fused together to form
continuous process that emerges from the cell
body.
4. Pseudounipolar neurons – begin in the
embryo as bipolar. Dendrites and axon fuse
together and become single in process.
Functional classification of neurons
1. Sensory or afferent neurons – (toward
carried), either contain sensory receptors at
their distal ends or are located just after
sensory receptors that are separate cells.
• Most sensory neurons are unipolar in
structure
Neuroglia
➢ Make up about half the volume of the CNS
➢ Generally, they are smaller neurons, and they
are about 5-25 times more numerous
➢ Do not generate or propagate action potentials
➢ They can multiply and divide in the mature
nervous system
➢ In cases of injury or diseases, they multiply to
fill in the spaces formerly occupied by the
neurons
➢ The name derived from the idea that they were
the “glue that held” nervous tissue together
Neuroglia of the CNS
1. Astrocytes – star-shaped cells having many
processes and are the largest and most
numerous of the neuroglia. Play a role in
learning and memory by influencing the
formation of neural synapses.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
2. Oligodendrocytes – resembles astrocytes but
smaller and contain fewer processes. Process
is responsible for forming and maintaining
myelin sheath around CNS axons.
3. Microglia or Microglial cells – small cells
with slender processes that give off numerous
spine-like projections. Function as phagocytes.
Ike tissue macrophages, they remove cellular
debris.
4. Ependymal cells – cuboidal to columnar cells
arranged in a single layer that possess
microvilli and cilia. Lines the ventricles of the
brain and the central canal of the spinal cord.
Neuroglia of the PNS
1. Schwann cells – encircles the PNS axons.
Form the myelin sheath around the axons.
Each Schwann cell myelinates a single axon
and can enclose as many as 20 or more
unmyelinated axons. Schwann cells participate
in axon generation, which is more easily
accomplished in PNS than in the CNS.
2. Satellite cells – flat cells surround the cell
bodies of neurons of PNS ganglia. Provides
structural support. Regulates the exchanges of
materials between neuronal cell bodies and
interstitial fluids.
Ion channels – Allows specific ions to move across
the plasma membrane.
1. Ligand-ligated channel – responses to a
binding of a ligand (chemical) stimulus, as a
result it causes the gate to open and close
2. Leak channels – the gates randomly alternate
between close and open position
3. Mechanically-gated channel – opens and
closes in response to mechanical stimulation in
the form of vibration (sound or waves), touch,
pressure, or tissue stretching
4. Voltage-gated channel – opens in response to
a change in membrane potential (voltage)
Generation and Transmission of Electrical
Impulses
➢ Like muscle fibers, neurons are electrically
excitable
➢ They communicate with one another using two
types of electrical signals
• Graded potentials – used for shirtdistance communication only
• Action potentials – allow
communication over long distances
within the body
o Muscle action potential –
action potential occurs in
muscle fibers
o Nerve action potential
(nerve impulse) – action
potential occurs in the neurons
(nerve cell)
➢ Graded potential, nerve and muscle actions
potential are involved in the relay of sensory
stimuli, integrative functions such as
perception, and motor activities
Electrochemical gradient – concentration difference
plus an electrical difference.
Sodium – principal ion in the fluid outside cell.
Potassium – principal ions in the fluid inside the cell.
Resting membrane potentials arise from three
major factors:
• Unequal distribution of ions in the
extracellular fluid and cytosol.
• Inability of most anions to leave the cell.
• Electrogenic nature of the Na+ - K+ ATPases.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Graded potential – Occurs when a stimulus causes
mechanically-gated or ligand-gated channels to open
or close in an excitable cell’s plasma membrane. Small
deviation from the resting membrane potential that
makes the membrane either more polarized inside
(inside more negative) or less polarized (inside less
negative).
1. Hyperpolarizing graded potential – makes
the membrane more polarized
2. Depolarizing graded potential – makes the
membrane less polarized
3. Decremental conduction – mode of travel
which grade potential die out as they spread
along the membrane
4. Summation – graded potentials add together,
become stronger, and at last longer compare to
graded potential which did not add together
Action potential – A sequence of rapidly occurring
events that decrease and reverse the membrane
potential and then eventually restore it to the resting
state.
1. Depolarizing phase – the negative membrane
potential becomes less negative, reaches zero,
and then becomes positive
2. Repolarizing phase – membrane potential is
restored to resting state of -70 Mv.
Two types of voltage-gated channels:
1. Voltage-gated Na+ channels – allows Na+ to
rush into the cell, which causes depolarizing
phase. Membrane potential changes from -55
mV to +30 mV.
2. Voltage-gated K+ channels – remain open
after repolarizing phase ends.
Depolarizing phase – Other stimulus causes the
membrane of the axon to depolarize to threshold.
Continuous conduction - it involves step-by-step
depolarization and repolarization of each adjacent
segment of the plasma membrane. Ion flows through
their voltage-gated channels in each adjacent segment
of the membrane.
Saltatory conduction - action potential that occurs
along myelinated axons, occurs due to uneven
distribution of voltage-gated channels.
Factors affecting speed of propagation:
• Amount of myelination
• Axon diameter
• Temperature
Synapse – is a region where communication occurs
between two neurons or between neurons and effector
cell.
Presynaptic neuron – carries a nerve impulse towards
the synapse.
Postsynaptic neuron – receives a signal, carries nerve
impulse away from a synapse or an effector cell that
responds to the stimulus at the synapse.
Electrical synapses – action potential directly
between the plasma membrane of an adjacent neurons
through the structure called gap junctions. Advantages
are: faster communication and synchronization
Chemical synapses – although the plasma membrane
of presynaptic and postsynaptic neuron in chemical
synapses are close, they do not touch. They are
separated by the synaptic cleft.
Neurotransmitter – there are more than hundred
known neurotransmitters. They have multiple types of
receptors which they can bind.
Anatomy and Function of the Spinal Cord
Spinal cord – located within the vertebral canal of the
vertebral column. Vertebral foramina of all the
vertebra, stacked one on top of the other, form the
vertebral canal.
Meninges – the three protective, connective tissue
coverings that encircle the spinal cord and brain
• The spinal meninges – surround the spinal
cord
• Cranial meninges – which encircles the brain.
Continuous from spinal meninges
All three spinal meninges cover the spinal nerves up to
the point where they exit the spinal column through the
invertebral foramina.
Spinal cord is also protected by cushion of fat and
connective tissue
External anatomy of spinal cord
Spinal cord – roughly oval in shape, being flattered
slightly anteriorly and posteriorly. Extends from
medulla oblongata to the superior border of the second
lumbar vertebra. There are two conspicuous
enlargements.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Cervical – superior enlargement (4th cervical – 1st
thorax).
Lumbar – inferior enlargement (9th-12th thoracic
vertebrae).
Vertebral column – spinal cord is located within the
vertebral canal of the vertebral column and divided
into 5 parts:
• Cervical vertebrae (C1-C8)
• Thoracic vertebrae (T1-T12)
• Lumbar Vertebrae (L1-L5)
• Sacral vertebrae (S1-S5)
• Coccygeal verterbae (C1)
Medulla oblongata – base of the brain that connects
the brain to the spinal cord.
Conus medullaris – the tapered, lower end of the
spinal cord.
Cauda equina – sack of nerve roots (nerves that leave
the spinal cord between spaces in the bones of the
spine to connect to other parts of the body.
Filum terminale – fibrous band that extends from the
conus medullaris to the periosteum of the coccyx.
Internal anatomy of spinal cord
Sulcus – denotes the location at which the ventral
fibers leave the spinal cord
White column – contains axon tracts related to
specific functions (dorsal, ventral and lateral)
Gray horn – column of gray matter in the spinal cord
(dorsal, ventral and lateral)
Gray commissure – gray matter that surrounds the
central canal and connects the two halves of the spinal
cord
Central canal – CSF-filled spaced that runs through
the spinal cord
Spinal ganglion – cluster of nerve bodies that contain
sensory neurons
Spinal nerve – controls the sensation in the body
Cell body of autonomic motor neuron
Cell body of inter neuron
Cell body of sensory neuron
Cell body of somatic motor neuron
Functions of the Spinal Cord
1. Carrying signals from the brain: the spinal
cord receives signals from the brain that
control movement and autonomic functions
2. Carrying information to the brain: the
spinal cord nerves also transmit messages to
the brain from the body, such as sensations of
touch, pressure and pain
3. Reflex response: the spinal cord may also act
independently of the brain in conducting
motor reflexes. One example is the patellar
reflex, which causes a person’s knee to
involuntarily jerk when tapped in a certain
spot
Spinal reflex
1. Stretch reflex (myotatic reflex) – a muscle
contraction in response to stretching within the
muscle.
2. Golgi tendon reflex – is a normal component
of the reflex arc of the PNS.
3. Crossed extension reflex – a withdrawal
reflex. Occurs when the flexors in the
withdrawing limb contract and the extensors
relax, while in the other limb, the opposite
occurs.
4. Withdrawal reflex – spinal reflex intended to
protect body from damaging stimuli.
Spinal nerves – are an integral part of the PNS. The
major nerves of the body. A total of 31 pairs of spinal
nerves control motor, sensory, and other functions.
➢ Located at the:
• Cervical (C1-C8)
• Thoracic (T1-T12)
• Lumbar (L1-L5)
• Sacral (S1-S5)
• Coccygeal levels (CO1)
➢ Transmit messages between the spinal cord
and the rest of the body, including muscles,
skin, and internal organs.
Cranial nerves – a set of 12-paired nerves in the back
of your brain. Sends electrical signals between the
brain, face, neck, and torso. Help us to be able to taste,
smell, hear, and feel sensations. Also aid in making
facial expressions, blinking eyes and moving tongue.
Two of the cranial nerve pairs originate in the
cerebrum – olfactory nerves and optic nerves.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Types of Cranial Nerves
I.
Olfactory nerve – sense of smell
II.
Optic nerve – sense of sight
III.
Oculomotor nerve – movement of the
eyeball, constriction of pupil in bright light or
for near vision, blinking
IV.
Trochlear nerve – movement of eyeball up
and down
V.
Trigeminal nerve – sensation in face, scalp,
teeth; contraction of chewing muscles
VI.
Abducens nerve – movement of eyeball
VII.
Facial nerve – sense of taste and, contraction
of facial muscles, secretion of saliva
VIII.
Acoustic/Auditory /vestibulocochlear/
vestibular nerve – sense of hearing; sense of
equilibrium.
IX.
Glossopharyngeal nerve – sense of taste,
sensory for cardiac, respiratory, and blood
pressure reflexes, contraction of pharynx,
secretion of saliva.
X.
Vagus nerve – sensory in cardiac, respiratory,
and blood pressure reflexes, sensory and motor
to larynx (speaking), decreases heart rate,
contraction of alimentary tube (peristalsis);
increases digestive secretions.
XI.
Accessory nerve – contraction of neck and
shoulder muscles; motor to larynx (speaking).
XII.
Hypoglossal nerve – movement of the tongue
➢ The neural folds along its central axis to form
a neural groove lined on each side by a neural
fold.
➢ The neural folds fuse together and pinch off to
become the neural tube. Fusion of the neural
folds begins in the middle of the embryo and
moves cranially and caudally
Neurulation – a process in which the neural plate
bends up and later fuses to form the hollow tube that
will eventually differentiate into the brain and the
spinal cord of the CNS.
The neural tube forms the three primary brain
vesicles.
Vesicles of the brain
➢ Nervous system develops when the notochord
induces its overlying ectoderm to become
neuroectoderm and develop into the neural
plate.
In summary, the primary vesicles help to establish the
basic regions of the nervous system: forebrain,
midbrain and hindbrain The secondary vesicles go on
to establish the major regions of the adult nervous
system.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Meninges – are the three layers of membranes that
cover and protect the brain and spinal cord (the CNS).
➢ They are known as:
• Dura mater
• Arachnoid mater
• Pia mater
3 spaces within the meninges:
1. Epidural Space – Space between your skull
and dura mater and the dura mater of the
spinal cord and the bone of the vertebral
column.
2. Subdural Space – Space between the dura
mater and the arachnoid mater. Under normal
conditions, this is not a space, but can be
opened if there’s a trauma to the brain (brain
bleed) or other medical conditions.
3. Subarachnoid Space – Space between the
arachnoid mater and pia mater. It’s filled with
cerebrospinal fluid.
Meninges protect the CNS from trauma injury to the
brain, such as low blow to the head, by acting as a
shock absorber
They anchor CNS and keep the brain from moving
around the skull
Provide a support system for blood vessels that deliver
blood to the CNS tissues, nerves, lympathics and the
CSF.
Dura Mater
➢ This is the outer layer, closest to your skull
➢ Thick, strong membrane layer located directly
under the skull and vertebral column
Arachnoid Mater
➢ This is the middle layer
➢ Thin layer that lies between the dura mater and
pia mater
➢ Doesn’t contain blood vessels or nerves
➢ Has a spiderweb-like appearance
Pia Mater
➢ This is the inner layer, closest to your brain
tissue
➢ Thin later that is held tightly, like shrink wrap,
to the surface of the brain and spinal cord
Together, the arachnoid mater and pia mater are
called Leptomeninges.
Cerebrospinal fluid – is the fluid around the brain and
spinal cord. It is a clear, plasma-like fluid that bathes
the CNS. Made by a group of cells, called the choroid
plexus, that are deep inside the brain. The body has
about 150 milliliters of fluid, roughly around twothirds of a cup. Occupies the central spinal canal, the
ventricular system and the subarachnoid space.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Functions of the CSF:
1. Support – the CSF supports the weight of the
brain estimated at 1500 gm and suspends it in
neutral buoyancy to a net weight of about 25
gm. Hence, the entire brain is cushioned,
protecting it from crushing into the bony
cranium.
2. Shock absorber – it protects the brain from
damage during head trauma.
3. Homeostasis – the biochemical constituents
and volume of the CSF play vital cerebral
homeostatic roles:
➢ Maintains stable intrinsic CNS
temperature.
➢ Biochemical constituents and
electrolytes maintain osmotic pressure
responsible for normal CSF pressure
which is essential to maintaining
normal cerebral perfusion.
➢ Biochemical waste products diffuse
into the CSF an are removed as CSF is
reabsorbed through arachnoid
granulations into venous circulation, a
small percentage of CSF also drains
into the lymphatic circulation.
4. Nutrition – the CSF contains glucose,
proteins, lipids, and electrolytes, providing
essential CNS nutrition.
5. Immune function – the CSF contain
immunoglobulins and mononuclear cells.
Autonomic Nervous System
➢ It is a component of the PNS that regulates
involuntary physiologic processes including
heart rate, blood pressure, respiration,
digestion, and sexual arousal
➢ The primary function of ANS is homeostasis.
Apart from maintaining the body internal
environment, it is also involved in controlling
and maintaining the following life processes:
• Digestion
• Metabolism
• Urination
• Defecation
• Blood pressure
• Sexual response
• Body temperature
• Heartbeat
• Breathing rate
• Fluid balance
➢ Innervates smooth and cardiac muscle to
generate involuntary motions
➢ After the ANS receives information about the
body and external environment, it responds by
stimulating body processes, usually through
the sympathetic division, or inhibiting them,
usually through the parasympathetic division
Two main divisions of Autonomic Nervous System:
• Sympathetic division
• Parasympathetic division
Autonomic pathways – are the means whereby the
central nervous system (CNS) sends commands to the
rest of the body
➢ Autonomic pathway consists of two neuron
chain:
• Preganglionic neuron – first motor
neuron that has its cell body in the
CNS and its preganglionic fiber
extends to autonomic ganglion.
Neurons of the intermediolateral
column of the spinal cord, found
within the levels T1-T12 and L1-L3.
o Preganglionic fibers – the
axons of the preganglionic
neurons that leave the spinal
cord through the anterior rami
of spinal nerves and continue
their path as white rami
communicates.
• Postganglionic neuron – second
motor neuron has its soma in that
autonomic ganglion and its
unmyelinated axon called the
postganglionic fiber extends directly
to the effector cell or organ.
Two autonomic pathways:
1. Sympathetic pathway
• Preganglionic
• Ganglionic
• Postganglionic
➢ Sympathetic ganglia – sympathetic trunk
(paravertebral ganglia); prevertebral
(splanchnic) ganglia; the neuronal bodies
of the sympathetic ganglia synapse with
the white rami communicates.
➢ Postganglionic components consist of
postganglionic neurons and their fibers.
The axons leave the ganglia and project
onto visceral effectors, where they release
the neurotransmitter norepinephrine. Both
preganglionic and postganglionic neurons
are MULTIPOLAR
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
➢ Postganglionic neurons – whose cell
body is in an autonomic ganglion.
➢ Postganglionic fibers – the axons of the
ganglion neurons that leave the ganglia in
the form of gray rami communicates
which join the rami of the spinal cord.
➢ Spinal nerves C2-C8 carry sympathetic
innervations to head, neck, upper limbs,
and thorax.
➢ Spinal nerves T1-L2 carry sympathetic
innervations for the trunk wall, as well as
participating in comprising the splanchnic
nerves for innervations of the abdominal
pelvic viscera.
➢ Spinal nerves L3-Co carries sympathetic
innervations to the cutaneous structures of
the lower limbs.
2. Parasympathetic pathway
➢ The PNS consists of many pathways that
connect its craniosacral components with
the peripheral tissues
➢ Each parasympathetic pathway consists of
two neurons, the pre-synaptic
(preganglionic) and post-synaptic
(postganglionic) neurons, which are
connected by the axons of the pre-synaptic
neurons.
➢ The pre-synaptic neurons of the
parasympathetic pathway are located
within the medulla oblongata and sacral
spinal cord. They give off long axons (presynaptic fibers) that leave the CNS and
travel towards the post-synaptic neurons.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Disorders of the Nervous System
1. Alzheimer’s disease – A progressive
neurologic disorder that causes the brain to
shrink (atrophy) and brain cells to die. A type
of dementia that affects a person’s thinking,
behavior. And ability to perform everyday
tasks. Associated with a build-up of certain
proteins and chemicals in the brain, which
leads to dementia symptoms that worsen over
time.
2. Multiple sclerosis – Literally, “hardenings”, it
is a disease of unknown cause that manifests
as multiple hard plaques of degeneration of the
insulating layer of nerve fibers in the CNS.
The loss of insulation allows “short circuiting
of nerve impulses”. Depending upon where the
degeneration occurs, patients may suffer
paralysis, sensory disturbances or blindness.
3. Cerebrovascular accident – The medical
term for stroke. A blood vessel in the brain
may burst causing internal bleeding or a clot
may arise and travel to get stuck in a brain
vessel which then deprives brain tissue of
oxygen. Depending upon the area of the brain
involved, the patient may suffer paralysis, loss
of speech or loss of vision.
4. Epilepsy – is a CNS (neurological) disorder in
which brain activity becomes abnormal,
causing seizures or periods of unusual
behavior, sensations and sometimes loss of
awareness. Two or more unprovoked seizures
occurring in an individual. Sometimes called a
seizure disorder, a disorder of the brain.
5. Aphasia – A language disorder cause by
damage in a specific area of the brain that
controls language expression and
comprehension. Leaves a person unable to
communicate effectively with others.
6. Cerebral palsy – A neurological condition
caused by brain damage, and it is the most
common motor and movement disability of
childhood. Refers to a group of disorders that
affect balance, movement, and muscles tone.
SENSES
General senses – are those with receptors widely
distributed throughout the body, including the skin,
various organs, and joints.
Special senses – have more specialized receptors and
are confined to structures in the head, such as the eyes
and ears.
Sensation – The raw form in which receptors send
information to the brain.
Perception – The way the brain interprets the
information.
Projection – The cerebral cortex interprets the
sensation formed as coming from the receptors being
stimulated.
Sensation – is the conscious or subconscious
awareness of external or internal stimuli.
➢ Purpose of Sensations – to detect changes in
the external or internal environment to enable
the body to respond appropriately to maintain
homeostasis.
➢ Sensory Pathway-pathway of impulses for a
sensation:
• Receptors – detect a change (usually
very specific) and generate impulses.
• Sensory neurons – transmit impulses
from receptors to the CNS.
• Sensory tracts – white matter in the
CNS.
• Sensory area – most are in the
cerebral cortex; feels and interprets the
sensation.
Characteristics of Sensations:
1. Projection – the sensation seems to come
from the area where the receptors were
stimulated, even though it is the brain that
truly feels the sensation.
2. Intensity – the degree to which a sensation is
felt; a strong stimulus affects more receptors
more impulses are sent to the brain and are
interpreted as a more intense sensation.
3. Contrast – the effect of a previous or
simultaneous sensation on a current sensation
as the brain compares them.
4. Adaptation – becoming unaware of a
continuing stimulus; if the stimulus remains
constant, there is no change for receptors to
detect.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
5. After-image – the sensation remains in the
consciousness after the stimulus has stopped.
Classification Of Sensory Receptor:
Touch and Pressure Senses
1. Free nerve endings – the simplest receptors,
are common in epithelial tissues, where they
lie between epithelial cells. They are
responsible for the sensation of itching.
2. Tactile (Meissner’s) corpuscles – are small,
oval masses of flattened connective tissue cells
in connective tissue sheaths. They provide fine
touch, such as distinguishing two points on the
skin where an object touches, to judge its
texture.
3. Lamellated (Pacinian) corpuscles – are
relatively large, ellipsoidal structures
composed of connective tissue fibers and cells.
Heavier pressure and stretch stimulate
lamellated corpuscles. They also detect
vibrations in tissues.
Receptor Location and Activating Stimuli
Temperature Senses (thermoreceptors)
➢ Those that respond to warmer temperatures are
warm receptors, and those that respond to
colder temperatures are cold receptors.
Sense of Pain
➢ Visceral Pain – pain receptors in these organs
respond differently to stimulation than those
associated with surface tissues. Visceral pain
may feel as if it is coming from some part of
the body other than the part being stimulated,
in a phenomenon called referred pain.
Pain Pathways
➢ The axons (fibers) that conduct impulses away
from pain receptors are of two main types: fast
pain fibers and slow pain fibers.
• The fast pain fibers (also known as
A-delta fibers) are myelinated. They
conduct impulses rapidly, at velocities
up to 30 meters per second.
• The slow pain fibers (C fibers) are
unmyelinated. They conduct
impulses more slowly than fast pain
fibers, at velocities up to 2 meters per
second.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Sense Of Smell (Olfaction)
➢ The receptors for olfaction are in the nasal
epithelium.
➢ Olfactory receptors are chemoreceptors that
chemicals dissolved in liquid stimulate
➢ They discharge nerve impulses, which are
transmitted via olfactory (II) nerves to
olfactory bulbs, from which they are
conducted via olfactory tracts to the olfactory
cortex (temporal and frontal lobes)
Sense of Taste (Gustation)
➢ The receptors for gustation are located in taste
buds.
➢ Taste cells have taste hairs that are sensitive to
particular chemicals dissolved in water.
➢ Chemical dissolved in saliva are detected by
taste receptors (buds) mainly on the tongue.
This results in generation of a receptor
potential and discharge of nerve impulses,
which are transmitted via cranial nerves (V,
VII, IX, X) to the gustatory cortex (parietal
lobe) and perceived as different tastes.
➢ Five basic tastes: sweet, sour, salty, bitter,
and savory; foods stimulate combinations of
receptors.
Sense of Vision
External and Accessory Structures of the Eye
1. Eyelids and eyelashes keep dust out of eyes.
Associated with the eyelashes are ciliary
glands, modified sweat glands and the
meibomian glands, which produce an oily
secretion that helps keep the eye lubricated.
2. The lacrimal apparatus includes a series of
ducts and lacrimal glands.
• Lacrimal glands produce tears, which
flow across the eyeball to two lacrimal
ducts, to lacrimal sac to nasolacrimal
duct to nasal cavity.
• Tears wash the anterior eyeball and
contain lysozyme to inhibit bacterial
growth.
3. The conjunctiva is a mucosa that lines the
eyelids and covers eye.
4. The six extrinsic muscles (superior, inferior,
lateral, and medial rectus and superior and
inferior oblique) move the eyeballs.
Internal Structures: The Eyeball
The wall of the eyeball is made up of three layers:
1. Fibrous tunic – The outermost fibrous layer
consists of the sclera and the cornea.
•
Sclera – outermost tough layer of the
eyeball, provides shape and protects
inner
• Cornea – allows light to enter the eye
and the first light-refracting structure
2. Vascular tunic – The middle, pigmented
vascular layer (uvea) consists of the choroid,
the ciliary body, and the iris.
• Choroid – provides nutrients to the
eye and prevents light scattering
within the eye.
• Ciliary body – consists of the ciliary
processes and ciliary.
o Ciliary processes – contain
blood capillaries that secretes
aqueous humor.
o Ciliary muscles – alters the
shape of the lens, adapting it
for near and far vision.
• Iris – controls the size of the pupil;
regulate the amount of light that enters
the eyeball.
3. Nervous tunic (retina) – The sensory layer,
or retina, consists of an outer pigmented layer
and an inner neural layer
➢ The neural layer contains
photoreceptors (rods and cones),
bipolar cells, and ganglion cells.
Ganglion cell axons form the optic
nerve, which exits via the optic disc
("blind spot").
➢ Rods – detect light; abundant toward
periphery of retina.
➢ Cones – detect color; abundant in
center of retina.
➢ Fovea – in the center of the macula
lutea; contains only cones, area or best
color vision.
➢ Optic disc – also called the blind spot
no rods or cones; optic nerve passes
through eyeball.
Cavities of the Eye
1. Posterior cavity – contains vitreous humor
(semisolid)) that keeps the retina in place.
2. Anterior cavity – contains aqueous humor
that nourishes the lens and cornea; formed by
capillaries in the ciliary processes, flows
through pupil, is reabsorbed to blood at the
canal of Schlemm. Aqueous humor is a major
factor in maintaining intraocular pressure.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Lens
➢ It is transparent, elastic structure.
➢ The biconvex lens is suspended within the eye
by the ciliary zonule attached to the ciliary
body.
➢ It is the only adjustable refractory structure of
the eye.
➢ Errors on refraction include: myopia,
hyperopia and astigmatism.
Errors of Refraction
➢ Normal visual acuity is referred to as 20/20;
that is, the eye should and does clearly see an
object 20 feet away.
1. Nearsightedness (myopia) – means that the
eye sees near objects well but not distant ones.
The nearsighted eye focuses images from
distant objects in front of the retina, because
the eyeball is too long or the lens too thick.
These structural characteristics of the eye are
hereditary Correction requires a concave lens
to spread out light rays before they strike the
eye.
2. Farsightedness (hyperopia) – means that the
eye sees distant objects well. Such an eye may
have an acuity of 20/10, that is, it sees at 20
feet what the normal eye can see only at 10
feet. The farsighted eye focuses light from
near objects "behind" the retina, because the
eyeball is too short or the lens too thin.
Correction requires a convex lens to converge
light rays before they strike the eye
3. As we get older, most of us will become more
farsighted (presbyopia). As the aging lens
loses its elasticity, it is not as able to recoil and
thicken for near vision, and glasses for reading
are often necessary.
4. Astigmatism – is another error of refraction,
caused by an irregular curvature of the cornea
or lens that Scatters light rays and blurs the
image on the retina. Correction requires a lens
ground specifically for the curvature of the
individual eye.
Image Formation – The eye forms clear images on
the retina.
• Refraction or bending of light by the lens and
cornea
• Accommodation: the change in shape of the
lens
o Lens is adjustable; ciliary muscle
relaxes for distant vision, and lens is
thin
o
•
Ciliary muscle contracts for near
vision, and elastic lens thickens and
has create refractive power.
Constriction or narrowing of the pupil
Physiology of Vision
1. Absorption of light by photopigments
• Light strikes retina and stimulates
chemical reactions in the rods and
cones.
• In rods: rhodopsin breaks down to
scotopsin and retinal (from vitamin
A), and an electrical impulse is
generated. In cones: specific
wavelengths of light are absorbed
(red, blue, green); chemical reactions
generate nerve impulses.
2. Generation and conduction of impulses
• Ganglion neurons from the rods and
cones form the optic nerve, which
passes through the eyeball at the optic
disc.
• Optic chiasma - site of the crossover
of medial fibers of both optic nerves,
permitting binocular vision.
3. Interpretation of visual images
• Visual areas in occipital lobes-each
area receives impulses from both eyes
• both areas create one image from the
two slightly different images of each
eye both areas right the upside-down
retinal image.
• Sense of hearing and equilibrium
The Ear: Hearing and Equilibrium
Anatomy of the ears
➢ It consists of three principal regions: the outer
ear, the middle ear, and the inner ear.
Outer Ear
1. Pinna – Collect and direct sound waves into
the ear.
2. External auditory meatus – Transmit sound
waves through the outer ear.
3. Tympanic membrane – Transmit pressure
waves to the malleus.
Middle Ear
1. Tympanic cavity – Connects with auditory
tube; contains auditory ossicles.
2. Auditory ossicles – Transmit and amplify
pressure waves.
3. Malleus
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
4. Incus
5. Stapes
6. Auditory tube – Equalizes pressure on both
sides of tympanic membrane.
Inner Ear
➢ Bony labyrinth
1. Vestibule – Receives pressure waves
via oval window; contains vestibule
utricle and saccule of vestibular
apparatus.
2. Semicircular canals – Contain
semicircular ducts of vestibular
apparatus.
3. Cochlea – Contains fluids (perilymph,
endolymph) for transmission of
pressure waves; contains organ for
hearing (organ of Corti)
➢ Membranous labyrinth
1. Utricle, saccule – Contain receptor
for static equilibrium.
2. Semicircular ducts – Contain
receptors for dynamic equilibrium.
Physiology of Hearing
➢ Sound waves stimulate vibration of eardrum,
malleus, incus, stapes, oval window of inner
ear, perilymph and endolymph of cochlea, and
hair cells of organ of Corti.
➢ When hair cells bend, impulses are generated
and carried by the 8th cranial nerve to the
auditory areas in the temporal lobes.
Sense of Equilibrium
➢ The organs associated with static equilibrium
sense the position of the head, maintaining
stability and posture when the head and body
are still.
➢ When the head and body suddenly move or
rotate, the organs of dynamic equilibrium
detect the motion and aid in maintaining
balance.
Body Equilibrium
➢ Utricle and saccule – membranous sacs in the
vestibule; each contains hair cells that are
affected by gravity.
➢ When position of the head changes, otoliths
bend the hair cells, which generate impulses
along the vestibular branch of the 8th cranial
nerve to the cerebellum, midbrain, and
cerebrum. Impulses are interpreted as position
of the head at rest.
➢ Semicircular canals – three membranous
ovals in three planes; enlarged base is the
ampulla, which contains hair cells (crista) that
are affected by movement.
➢ As body moves, hair cells bend in opposite
direction generate impulses along vestibular
branch of 8th cranial nerve to cerebellum,
midbrain, and cerebrum.
➢ Impulses are interpreted as movement of the
body, changing speed, stopping or starting.
Vision and Hearing Disorders
1. Color blindness – is due to a congenital lack
of one or more of the cone types. Inherited as
an X-linked condition, it is far more common
in males than in females.
2. Vertigo – is sensation of spinning or
movement in which the world seems to
revolve or the person seems to revolve in
space.
3. Cataract – is the loss of transparency of the
lens.
4. Glaucoma – is an abnormally high intraocular
pressure due to the buildup aqueous humor in
the anterior cavity.
5. Keritis – is an inflammation or infection of
the cornea.
6. Otitis media – is an acute infection of the
middle ear caused by bacteria and associated
with the infections of the nose and throat.
7. Nystagmus – is a rapid involuntary movement
of the eyeballs possibly caused by a disease of
the CNS.
ENDOCRINE SYSTEM
Endocrine glands – are ductless, well-vascularized
glands that release hormones directly into the blood or
lymph.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
Functions of the Endocrine System
1. Help regulates
➢ Chemical composition and volume of
internal environment (interstitial fluid)
➢ Metabolism and energy
➢ Contraction of smooth and cardiac
muscle fibers
➢ Glandular secretions
➢ Some immune system activities
2. Control growth and development
➢ Regulate operation of reproductive
system
➢ Help establish circadian rhythms
Hormones exert their effects on target organs or
tissues.
Chemistry of Hormones
1. Amines – structural variations of the amino
acid tyrosine; thyroxine, epinephrine.
2. Proteins – chains of amino acids; peptides are
short chains. Insulin, GH, glucagon are
proteins; ADH and oxytocin are peptides.
3. Steroids – made from cholesterol; cortisol,
aldosterone, estrogen, testosterone.
Regulation of Hormone Secretion
➢ Hormones are secreted when there is a need
for their effects. Each hormone has a specific
stimulus for secretion.
➢ The secretion of most hormones is regulated
by negative feedback mechanisms: As the
hormone exerts its effects, the stimulus for
secretion is reversed, and Secretion of the
hormone decreases.
The major endocrine organs:
1. Pituitary gland
2. Thyroid gland
3. Parathyroid gland
4. Adrenal gland
5. Pineal gland
6. Thymus glands
7. Pancreas
8. Gonads
9. Hypothalamus – is a neuroendocrine organ.
A. Pituitary Gland (Hypophysis)
1. Posterior Pituitary (Neurohypophysis) –
stores hormones produced by the
hypothalamus.
• Antidiuretic hormone (ADH) –
stimulates the kidney tubules to
reabsorb and conserve water, resulting
in small volumes of highly
concentrated urine and decreased
plasma osmolality. ADH is released in
response to high solute concentrations
in the blood and inhibited by low
solution concentrations in the blood.
o Hyposecretion results in
diabetes insipidus.
• Oxytocin (OT) – stimulates
contraction of myometrium of uterus
during labor and release of milk from
mammary glands.
2. Anterior Pituitary (Adenohypophysis) –
secretions are regulated by releasing hormones
from the hypothalamus.
• Growth hormone (GH) – is an
anabolic hormone that stimulates
growth of all body tissues but
especially skeletal muscle and bone.
GH mobilizes fats, stimulates protein
synthesis, and inhibits glucose uptake
and metabolism.
o Hyposecretion in children
causes pituitary dwarfism.
• Thyroid-stimulating hormone
(TSH) – promotes normal
development and activity of the
thyroid gland.
• Adrenocorticotropic hormone
(ACTH) – stimulates the adrenal
cortex to release corticosteroids.
• Prolactin (PRL) – promotes milk
production in humans.
• Follicle-stimulating hormone (FSH)
– In women: initiates development of
ova in ovarian follicles and secretion
of estrogen by follicle cells. In men:
initiates sperm development in the
testes.
• Luteinizing hormone (LH) – In
women: stimulates ovulation,
transforms mature follicle into corpus
luteum and stimulates secretion of
progesterone. In men: stimulates
secretion of testosterone by the testes.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
B. Thyroid Gland
1. Thyroxine (T4) and triiodothyronine (T3) –
Increase use of all food types for energy
protein synthesis. Necessary for normal
physical, mental, and sexual development.
• Graves’ disease – is the most
common cause of hyperthyroidism.
• Cretinism – is the hyposecretion; in
infants and myxedema in adults.
2. Calcitonin – produced by parafollicular cells
of the thyroid gland in response to rising
resorption and enhancing calcium deposit in
bone. It depresses blood calcium levels by
inhibiting bone matrix resorption and
enhancing calcium deposit in bone.
C. Parathyroid Glands
1. Parathyroid hormone (PTH) – increases
reabsorption of calcium and phosphate from
bones to the blood; increases absorption of
calcium and phosphate by the small intestine;
increases resorption of calcium and excretion
of phosphate by the kidneys, and activates
vitamin D.
• Hyperparathyroidism – results in
hypercalcemia. and all its effects and
in extreme bone wasting.
• Hypoparathyroidism – leads to
hypocalcemia, evidenced by tetany
and respiratory paralysis.
D. Pancreas – is both an exocrine and an
endocrine gland. Islets of Langerhans
(endocrine portion) contain alpha cells and
beta cells.
1. Glucagon – secreted by alpha cells. Stimulates
liver to change glycogen to glucose increases
use of fats and amino acids for energy.
2. Insulin – secreted by beta cells. Increases use
of glucose by cells to produce energy;
stimulates liver and muscles to change glucose
to glycogen; increases cellular intake of fatty
acids and amino acids to use for synthesis of
lipids and proteins.
• Hyposecretion of insulin results in
diabetes mellitus; cardinal signs are
polyuria, polydipsia, and polyphagia.
E. Adrenal Glands – The paired adrenal
(suprarenal) glands superior to and the
kidneys. Each adrenal gland has two
functional portions, the out adrenal cortex and
the inner adrenal medulla.
• Adrenal medulla – produces
catecholamines (epinephrine and
norepinephrine) in response to
sympathetic nervous system
stimulation. Its catecholamines
enhance and prolong the fight-orflight response to short-term stressors.
• Adrenal cortex – produces
mineralocorticoids, glucocorticoids,
and very small amounts of sex
hormones.
1. Mineralocorticoids (primarily aldosterone)
– regulate sodium ion reabsorption and
potassium ion excretion by the kidneys.
Sodium ion reabsorption leads to water
reabsorption, and increases in blood volume
and blood pressure.
2. Glucocorticoids (primarily cortisol) – are
important metabolic hormones help the body
resist stressors by increasing blood glucose,
fatty acid and amino acid levels, and blood
pressure. High levels of glucocorticoids
depress the immune system and the
inflammatory response.
• Hypoactivity of the adrenal cortex
results in Addison's disease
• Hypersecretion can result in
aldosteronism, Cushing's syndrome
and adrenogenital syndrome.
F. Ovaries – The ovaries release two main
hormones (estrogen and progesterone).
1. Estrogen – Promotes maturation of ovum,
stimulates growth of blood vessels in
endometrium; stimulates development of
secondary sex characteristics: growth of duct
system of mammary glands, growth of uterus,
fat deposition. Promotes closure of epiphyses
of long bones; lowers blood levels of
cholesterol and triglycerides.
2. Progesterone – produced by the corpus
luteum. Promotes storage of glycogen and
further growth of blood vessels in the
endometrium, promotes growth of secretory
cells of mammary glands.
HUMAN ANATOMY AND PHYSIOLOGY
MIDTERM NOTES
G. Testes – The testes of the male begin to
produce testosterone and inhibin.
1. Testosterone – produced by interstitial cells.
Promotes maturation of sperm in testes;
stimulates development of secondary sex
characteristics: growth of reproductive organs,
facial and body hair, larynx, skeletal muscles;
promotes closure of epiphyses of long bones.
2. Inhibin – produced by sustentacular cells.
Inhibits secretion of FSH to maintain a
constant rate of sperm production.
H. Pineal gland – Its primary hormone is
melatonin, which influences daily rhythms an
may have an antigonadotrophic effect in
humans.
I. Thymus gland – The thymus gland is located
in the upper thorax, declines in size and
function with age. Its hormones, thymosins,
thymic factor, and thymopoietins, are
important to the normal development of the
immune response.
Other Hormone-Producing Structures
➢ Many body organs not normally considered
endocrine organs contain isolated cell clusters
that secrete hormones.
• the heart (atrial natriuretic peptide)
• gastrointestinal tract (gastrin, secretin,
and others);
• the placenta (hormones of pregnancy –
estrogen, progesterone, and others)
• the kidneys (erythropoietin and renin)
• skin (cholecalciferol)
• adipose tissue (leptin and resistin)