P. 94
Anatomy & Physiology 1
Mrs. Linde
1. adip-
= fat
2. areola- = open
space
3. chondr- = cartilage
4. -crine = secretion
5. -ectomy = to cut
out
6. epi- = upon
7. exo- = outer
8. -glia = glue
9. hist- = tissue
10. meso- = middle
11. neuro- = nerve
12. os- = bone
13. pseudo- = false
14. retic- = net
15. squam- = scale
16. strat- = layer
17. viscero- = body
organ

Cells are highly organized living units, but they
typically do not function alone. Instead, cells
work together in groups called tissues groups
of similar cells that function together to carry
out specialized activities. Histology is the
science that deals with the study of tissues. A
pathologist is a physician who specializes in
laboratory studies of cells and tissues to help
other physicians make accurate diagnoses; they
examine tissues for any changes that might
indicate disease.
Body tissues are classified into four basic types based on
their structure and functions:
1. Epithelial tissue covers body surfaces; lines body
cavities, hollow organs, and ducts (tubes); and forms
glands.
2. Connective tissue protects and supports the body and its
organs, binds organs together, stores energy reserves as
fat, and provides immunity.
3. Muscular tissue generates the physical force needed to
make body structures move.
4. Nervous tissue detects changes inside and outside the
body and initiates and transmits nerve impulses (action
potentials) that coordinate body activities to help
maintain homeostasis.
A.
Most cells are tightly joined into functional units by points
of contact between their plasma membranes called cell
junctions.
1. Some fuse cells together so tightly that they prevent
substances from passing between the cells.
a. Important for tissues that line the stomach,
intestines, and urinary bladder prevents the
contents from leaking out.
2. Others hold cells together so that they don’t separate
while performing their functions.
3. Still others form channels that allow ions and
molecules to pass between cells = permits cells in a
tissue to communicate with each other, enables nerve
or muscle impulses to spread rapidly among cells.
A.
Two types of epithelial tissue (epithelium):
(1) Covering and lining epithelium forms
outer covering of the skin and some internal
organs; lines body cavities, blood vessels,
ducts, and the interiors of the respiratory,
digestive, urinary, and reproductive systems. It
makes up, along with nervous tissue, the parts
of the sense organs for hearing, vision, and
touch
(2) Glandular epithelium makes up the
secreting portion of glands, such as sweat
glands.
1. Epithelium consists of closely packed cells with little
extracellular material between them, and the cells are
arranged in continuous sheets, in either single or multiple
layers.
2. Epithelial cells have a(n):
a. apical (free) surface, which is exposed to a body cavity,
lining of an internal organ, or the exterior of the body
b. lateral surfaces, which face adjacent cells on either side
c. basal surface, which is attached to a basement membrane.
3. Epithelia are avascular = they lack blood vessels. The vessels
that supply nutrients to and remove wastes from epithelia are
located in adjacent connective tissues. They exchange
materials by diffusion.
4. Epithelia have a nerve supply.
5. Because epithelium is subject to a certain amount of wear and
tear and injury, it has a high capacity for renewal by cell
division.
1. Arrangement of cells in layers. Cells are arranged
depending on the functions the epithelium performs:
a. Simple epithelium single layer of cells that functions
in diffusion, osmosis, filtration, secretion
(production/release of mucus/sweat/enzymes), and
absorption (intake of fluids/substances).
b. Pseudostratified epithelium appears to have multiple
layers of cells because the cell nuclei lie at different levels
and not all cells reach the apical surface.
c. Stratified epithelium consists of two or more layers
of cells that protect underlying tissues where there is
considerable wear and tear.
2. Cell shapes:
a. Squamous cells flat, arranged like floor tiles, and
thin = rapid passage of substances.
b. Cuboidal cells as tall as they are wide, and shaped
like cubes or hexagons; may have microvilli and function in
either secretion or absorption.
c. Columnar cells much taller than they are wide (like
columns) and protect underlying tissues. May have cilia or
microvilli, and often are specialized for secretion and
absorption.
d. Transitional cells change shape, from flat to
cuboidal, as organs (like urinary bladder) stretch to a
larger size and then collapse to a smaller size.
A. Simple squamous epithelium
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Description: Single layer of flat cells; centrally
located nucleus.
Location: Lines heart, blood vessels, lymphatic
vessels, air sacs of lungs, Bowman’s capsule of
kidneys, and inner surface of the eardrum; forms
epithelial layer of serous membranes, such as the
peritoneum.
Function: Filtration, diffusion, osmosis, and
secretion in serous membranes.
B. Simple cuboidal epithelium
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Description: Single layer of cube-shaped cells;
centrally located nucleus.
Location: Covers surface of ovary, lines anterior
surface of capsule of the lens of the eye, forms
the pigmented epithelium at the posterior
surface of the eye, lines kidney tubules and
smaller ducts of many glands, and makes up the
secreting portion of some glands such as the
thyroid gland.
Function: Secretion and absorption.
C. Nonciliated simple columnar epithelium
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Description: Single layer of nonciliated columnlike cells with nuclei near bases of cells; contains
goblet cells and cells with microvilli in some
locations.
Location: Lines most of the gastrointestinal tract
(from the stomach to the anus), ducts of many
glands, and gallbladder.
Function: Secretion and absorption.
D. Ciliated simple columnar epithelium
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Description: Single layer of ciliated column-like
cells with nuclei near bases; contains goblet cells
in some locations.
Location: Lines a few portions of upper
respiratory tract, uterine (fallopian) tubes,
uterus, some paranasal sinuses, and central canal
of spinal cord.
Function: Moves mucus and other substances by
ciliary action.
E. Pseudostratified columnar epithelium
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Description: Not a true stratified tissue; nuclei of cells
are at different levels; all cells are attached to
basement membrane, but not all reach the apical
surface.
Location: Pseudostratified ciliated columnar epithelium
lines the airways of most of upper respiratory tract;
pseudostratified nonciliated columnar epithelium lines
larger ducts of many glands, epididymis, and part of
male urethra.
Function: Secretion and movement of mucus by ciliary
action.
F. Stratified squamous epithelium
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Description: Several layers of cells; cuboidal to
columnar shape in deep layers; squamous cells form the
apical layer and several layers deep to it; cells from the
basal layer replace surface cells as they are lost.
Location: Keratinized variety forms superficial layer of
skin; nonkeratinized variety lines wet surfaces, such as
lining of the mouth, esophagus, part of epiglottis, part
of pharynx, and vagina, and covers the tongue.
Function: Protection.
G. Stratified cuboidal epithelium
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Description: Two or more layers of cells in which
cells in the apical layer are cube-shaped.
Location: Ducts of adult sweat glands and
esophageal glands and part of male urethra.
Function: Protection and limited secretion and
absorption.
H. Stratified columnar epithelium
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Description: Several layers of irregularly shaped
cells; only the apical layer has columnar cells.
Location: Lines part of urethra, large excretory
ducts of some glands such as esophageal glands,
small areas in anal mucous membrane, and a
part of the conjunctiva of the eye.
Function: Protection and secretion.
I. Transitional epithelium
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Description: Appearance is variable
(transitional); shape of cells in apical layer
ranges from squamous (when stretched) to
cuboidal (when relaxed).
Location: Lines urinary bladder and portions
of ureters and urethra.
Function: Permits distention.
J. Endocrine glands
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Description: Secretory products (hormones) diffuse
into blood after passing through interstitial fluid.
Location: Examples include pituitary gland at base of
brain, pineal gland in brain, thyroid and parathyroid
glands near larynx, adrenal glands superior to
kidneys, pancreas near stomach, ovaries in pelvic
cavity, testes in scrotum, and thymus in thoracic
cavity.
Function: Produce hormones that regulate various
body activities.
K. Exocrine glands
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Description: Secretory products released into
ducts.
Location: Sweat, oil, and earwax glands of the
skin; digestive glands such as salivary glands,
which secrete into mouth cavity, and pancreas,
which secretes into the small intestine.
Function: Produce substances such as sweat, oil,
earwax, saliva, or digestive enzymes.

Connective tissue is one of the most abundant
and widely distributed tissues in the body. In its
various forms, connective tissue has a variety of
functions. It binds together, supports, and
strengthens other body tissues; protects and
insulates internal organs; compartmentalizes
structures such as skeletal muscles; is the major
transport system within the body (blood, a fluid
connective tissue); is the major site of stored
energy reserves (adipose, or fat tissue); and is
the main site of immune responses.
1.
2.
Two basic elements: cells and extracellular matrix the
material between its widely spaced cells. The
extracellular matrix consists of protein fibers and ground
substance, the material between the cells and the
fibers. The extracellular matrix is usually secreted by
the connective tissue cells and determines the tissue’s
qualities (in cartilage, matrix is firm but pliable; in
bone, it is hard and not pliable.
Unlike epithelia: Connective tissues do not usually occur
on body surfaces, and usually are highly vascular (have a
rich blood supply). Exceptions include cartilage, which is
avascular, and tendons, with a scanty blood supply. Like
epithelia: Except for cartilage, connective tissues are
supplied with nerves.
1. Fibroblasts large, flat cells with branching processes present
in several connective tissues, and usually the most numerous.
Fibroblasts migrate through the connective tissue, secreting the
fibers and ground substance of the extracellular matrix.
2. Macrophages develop from monocytes, a type of white blood
cell. Macrophages have an irregular shape with short branching
projections and are capable of engulfing bacteria and cellular
debris by phagocytosis.
3. Plasma cells small cells that develop from a type of white
blood cell called a B lymphocyte. Plasma cells secrete antibodies,
proteins that attack or neutralize foreign substances in the body
= important part of the body’s immune response.
4. Mast cells abundant alongside the blood vessels that supply
connective tissue. They produce histamine, a chemical that
dilates small blood vessels as part of the inflammatory response,
the body’s reaction to injury or infection. Mast cells can also kill
bacteria.
5. Adipocytes fat cells or adipose cells, are connective tissue
cells that store triglycerides (fats). They are found below the skin
and around organs such as the heart and kidneys.
 Each
type of connective tissue has unique
properties, based on the specific
extracellular materials between the cells.
The extracellular matrix consists of a fluid,
gel, or solid ground substance plus protein
fibers.
Ground substance, the component of a
connective tissue between the cells and fibers,
supports cells, binds them together, and provides
a medium through which substances are
exchanged between the blood and cells. The
ground substance plays an active role in how
tissues develop, migrate, proliferate, and
change shape, and in how they carry out their
metabolic functions.
 Ground substance contains water and an
assortment of large organic molecules, many of
which are complex combinations of
polysaccharides and proteins.
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 Fibers
in the extracellular matrix strengthen
and support connective tissues. Three types
of fibers are embedded in the extracellular
matrix between the cells: collagen fibers,
elastic fibers, and reticular fibers.
1.
2.
3.
Very strong and resist pulling forces, but they
are not stiff, which promotes tissue flexibility.
Often occur in bundles lying parallel to one
another = great strength.
Consist of the protein collagen = the most
abundant protein in your body, representing
about 25% of total protein. Found in most types
of connective tissues, especially bone,
cartilage, tendons, and ligaments.
 Despite
their strength, ligaments may be
stressed beyond their normal capacity. This
results in sprain, a stretched or torn
ligament. The ankle joint is most frequently
sprained. Because of their poor blood supply,
the healing of even partially torn ligaments is
a very slow process; completely torn
ligaments require surgical repair.
1.
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4.
Smaller in diameter than collagen fibers;
branch and join together to form a network
within a tissue.
Consists of elastin (protein) surrounded by
fibrillin (glycoprotein), which is essential to
the stability of an elastic fiber.
Strong, but can be stretched up to one-and-ahalf times their relaxed length without
breaking; also have the ability to return to
their original shape after being stretched =
elasticity.
Plentiful in skin, blood vessel walls, and lung
tissue.

Marfan syndrome (MAR-fan) is an inherited disorder caused by
a defective fibrillin gene. The result is abnormal development
of elastic fibers. Tissues rich in elastic fibers are malformed or
weakened. Structures affected most seriously are the covering
layer of bones (periosteum), the ligament that suspends the
lens of the eye, and the walls of the large arteries. People
with Marfan syndrome tend to be tall and have
disproportionately long arms, legs, fingers, and toes. A
common symptom is blurred vision caused by displacement of
the lens of the eye. The most life-threatening complication of
Marfan syndrome is weakening of the aorta (the main artery
that emerges from the heart), which can suddenly burst.
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2.
Consist of collagen and a coating of
glycoprotein, provide support in the walls of
blood vessels and form branching networks
around fat cells, nerve fibers, and skeletal and
smooth muscle cells.
Much thinner than collagen fibers, but like
collagen fibers, provide support and strength
and also form the stroma (= bed or covering) or
supporting framework of many soft organs,
such as the spleen and lymph nodes. These
fibers also help form the basement membrane.
A.
Areolar connective tissue
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Description: Consists of fibers (collagen, elastic, and
reticular) and several kinds of cells (fibroblasts,
macrophages, plasma cells, adipocytes, and mast
cells) embedded in a semifluid ground substance.
Location: Subcutaneous layer deep to skin;
superficial region of dermis of skin; lamina propria of
mucous membranes; and around blood vessels,
nerves, and body organs.
Function: Strength, elasticity, and support.
B. Adipose tissue
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Description: Consists of adipocytes, cells specialized to
store triglycerides (fats) as a large centrally located
droplet; nucleus and cytoplasm are peripherally located.
Location: Subcutaneous layer deep to skin, around heart
and kidneys, yellow bone marrow, and padding around
joints and behind eyeball in eye socket.
Function: Reduces heat loss through skin, serves as an
energy reserve, supports, and protects.
D. Dense regular connective tissue
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Description: Extracellular matrix looks shiny white;
consists mainly of collagen fibers regularly arranged in
bundles; fibroblasts present in rows between bundles.
Location: Forms tendons (attach muscle to bone), most
ligaments (attach bone to bone), and aponeuroses
(sheetlike tendons that attach muscle to muscle or
muscle to bone).
Function: Provides strong attachment between various
structures.
E. Dense irregular connective tissue
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Description: Consists predominantly of collagen fibers
randomly arranged and a few fibroblasts.
Location: Fasciae (tissue beneath skin and around
muscles and other organs), deeper region of dermis of
skin, periosteum of bone, perichondrium of cartilage,
joint capsules, membrane capsules around various
organs (kidneys, liver, testes, lymph nodes), pericardium
of the heart, and heart valves.
Function: Provides strength.
F. Elastic connective tissue
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Description: Consists predominantly of freely
branching elastic fibers; fibroblasts are present
in spaces between fibers.
Location: Lung tissue, walls of elastic arteries,
trachea, bronchial tubes, true vocal cords,
suspensory ligament of penis, and ligaments
between vertebrae.
Function: Allows stretching of various organs.
C. Reticular connective tissue
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Description: A network of interlacing reticular fibers
and reticular cells.
Location: Stroma (supporting framework) of liver,
spleen, lymph nodes; red bone marrow, which gives rise
to blood cells; reticular lamina of the basement
membrane; and around blood vessels and muscles.
Function: Forms stroma of organs; binds together
smooth muscle tissue cells; filters and removes worn-out
blood cells in the spleen and microbes in lymph nodes.
G. Hyaline cartilage
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Description: Consists of a bluish-white, shiny ground
substance with fine collagen fibers and many
chondrocytes; most abundant type of cartilage.
Location: Ends of long bones, anterior ends of ribs,
nose, parts of larynx, trachea, bronchi, bronchial tubes,
and embryonic and fetal skeleton.
Function: Provides smooth surfaces for movement at
joints, as well as flexibility and support.
H. Fibrocartilage
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Description: Consists of chondrocytes scattered
among bundles of collagen fibers within the
extracellular matrix.
Location: Pubic symphysis (point where hip
bones join anteriorly), intervertebral discs (discs
between vertebrae), menisci (cartilage pads) of
knee, and portions of tendons that insert into
cartilage.
Function: Support and fusion.
I. Elastic cartilage
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Description: Consists of chondrocytes
located in a threadlike network of elastic
fibers within the extracellular matrix.
Location: Lid on top of larynx (epiglottis),
part of external ear (auricle), and auditory
(eustachian) tubes.
Function: Gives support and maintains
shape.

Bones are organs composed of several different
connective tissues, including bone or osseous
tissue. Bone tissue has several functions. It
supports soft tissues, protects delicate
structures, and works with skeletal muscles to
generate movement. Bone stores calcium and
phosphorus; stores red bone marrow, which
produces blood cells; and houses yellow bone
marrow, a storage site for triglycerides.
1.
2.
Blood tissue (blood) connective tissue with a liquid
extracellular matrix called blood plasma = pale yellow
fluid that consists mostly of water with a wide variety of
dissolved substances: nutrients, wastes, enzymes,
hormones, respiratory gases, and ions. Suspended in the
plasma are red blood cells, white blood cells, and
platelets. Red blood cells transport O2 to body cells and
remove CO2 from them. White blood cells are involved in
phagocytosis, immunity, and allergic reactions. Platelets
participate in blood clotting.
Lymph fluid that flows in lymphatic vessels. It is a
connective tissue that consists of several types of cells in
a clear extracellular matrix similar to blood plasma but
with much less protein.

Muscular tissue consists of elongated cells called muscle
fibers that are highly specialized to generate force. As a
result of this characteristic, muscular tissue produces
motion, maintains posture, and generates heat. It also
offers protection. Based on its location and certain
structural and functional characteristics, muscular tissue
is classified into three types:
Skeletal muscle tissue is named for its location—it is usually
attached to the bones of the skeleton.
2. Cardiac muscle tissue forms the bulk of the wall of the
heart.
3. Smooth muscle tissue is located in the walls of hollow
internal structures such as blood vessels, airways to the
lungs, the stomach, intestines, gallbladder, and urinary
bladder.
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Despite the awesome complexity of the
nervous system, it consists of only two
principal types of cells:
1.
2.
Neurons or nerve cells sensitive to various
stimuli; convert stimuli into nerve impulses
(action potentials) and conduct these impulses
to other neurons, to muscle fibers, or to
glands.
Neuroglia do not generate or conduct nerve
impulses, but they do have many other
important supportive functions.
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Membranes flat sheets of pliable tissue that
cover or line a part of the body. The combination
of an epithelial layer and an underlying
connective tissue layer constitutes an epithelial
membrane. The principal epithelial membranes
of the body are mucous membranes, serous
membranes, and the cutaneous membrane, or
skin. Another kind of membrane, a synovial
membrane, lines joints and contains connective
tissue but no epithelium.
1.
2.
3.
Lines a body cavity that opens directly to the exterior =
line the entire digestive, respiratory, and reproductive
systems and much of the urinary system.
The epithelial layer of a mucous membrane secretes
mucus, which prevents the cavities from drying out. It
also traps particles in the respiratory passageways,
lubricates and absorbs food as it moves through the
gastrointestinal tract, and secretes digestive enzymes.
The connective tissue layer helps bind the epithelium to
the underlying structures. It also provides the epithelium
with oxygen and nutrients and removes wastes via its
blood vessels.
1.
2.
Line body cavities that don’t open directly to the exterior, and
it also covers the organs that lie within the cavity.
Two parts:
a. Parietal layer part attached to the cavity wall
b. Visceral layer part that covers and attaches to the organs inside
these cavities. Each layer consists of areolar connective tissue
covered by mesothelium. Mesothelium is a simple squamous
epithelium. It secretes serous fluid, a watery lubricating fluid that
allows organs to glide easily over one another or to slide against
the walls of cavities.
3.
The serous membrane lining the thoracic cavity and covering
the lungs is the pleura. The serous membrane lining the heart
cavity and covering the heart is the pericardium. The serous
membrane lining the abdominal cavity and covering the
abdominal organs is the peritoneum.
1.
2.
3.
Line the cavities of some joints.
Composed of areolar connective tissue and
adipose tissue with collagen fibers; NO
EPITHELIAL LAYER.
Contain cells which secrete synovial fluid to
lubricate the ends of bones as they move at
joints, nourishe the cartilage covering the
bones, and remove microbes and debris
from the joint cavity.
New cells from stroma or parenchyma
 Epithelial cells originate from stem cells in defined
areas of tissue layer
 Bone regenerates readily, cartilage poorly
 Muscular tissue can replace cells but slowly
 Nerve tissue is poorest at replacement although
some stem cells seem to be available.
 Replacement from stroma –> scar tissue &
functional loss.
