Review of Anatomy and
Physiology
Muscular System, Skeletal System, Gastrointestinal System, Special Senses and
Neurological System
RLE112 NGIMEPC
Week 2 Session
The Skeletal System
 Parts of the skeletal system
 Bones (skeleton)
 Joints
 Cartilages
 Ligaments
 Divided into two divisions
 Axial skeleton
 Appendicular skeleton
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publishing as Benjamin Cummings
Functions of Bones
 Support of the body
 Protection of soft organs
 Movement due to attached skeletal
muscles
 Storage of minerals (Ca and P) and fats
 Blood cell formation - hematopoiesis
Types of Bone Cells
 Osteocytes
 Mature bone cells
 Osteoblasts
 Bone-forming cells
 Osteoclasts
 Bone-destroying cells
 Break down bone matrix for remodeling and release
of calcium
 Bone remodeling is a process by both
osteoblasts and
osteoclasts
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Slide 5.4
Bones of the Human Body
 The adult skeleton has 206 bones
 Two basic types of osseous - bone tissue
 Compact bone
 Dense and Homogeneous
 Spongy bone
 Small needle-like
pieces of bone
 Many open
spaces
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Classification of Bones on the Basis of Shape
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Figure 5.1
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Classification of Bones
 Bones are classifies according to shape
into four groups:
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 Long bones
 Typically longer than wide
 Have a shaft with heads at both ends
 Contain mostly compact bone
• Examples: Femur, humerus
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Classification of Bones
 Short bones
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 Generally cube-shape
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 Contain mostly spongy bone
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 Examples: Carpals, tarsals
 Sesamoid bones – form within tendons
 Examples: patella or kneecap
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Classification of Bones
 Flat bones
 Thin and flattened
 Usually curved
 Thin layers of compact bone around a layer
of spongy bone
 Examples: Skull, ribs, sternum
Classification of Bones
 Irregular bones
 Irregular shape
 Do not fit into other bone classification
categories
 Example: Vertebrae and hip
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Cummings
Slide 5.10
Gross Anatomy of a Long Bone
 Diaphysis
 Shaft - length
 Composed of
compact bone
 Epiphysis
 Ends of the bone
 Composed mostly of
spongy bone
Figure
5.2a5.11
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Slide
Structures of a Long Bone
 Periosteum
 Outside covering of the
diaphysis
 Fibrous connective tissue
membrane
 Sharpey’s fibers
 Secure periosteum to
underlying bone
 Arteries
 Supply bone cells
Figure 5.2c
with nutrients Copyright © 2003 Pearson Education, Inc. publishing
Slide 5.12
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Bone Growth
 Epiphyseal plates allow for growth of long bone
during childhood
 New cartilage is continuously formed
 Older cartilage becomes ossified
 Cartilage is broken down
 Bone replaces cartilage
 Process of bone formation – ossification done by boneforming cells called osteoblasts
Bone Growth
 Bones are remodeled and lengthened until
growth stops
 Bones change shape somewhat
 Bones grow in width – appositional growth
 Growth due to growth hormones and sex
hormones
 Bones are remodeled continually in response to:
 Calcium levels in blood and pull of gravity and
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Slide 5.14
muscles on theCopyright
bones
Bone Fractures
 A break in a bone
 Types of bone fractures
 Closed (simple) fracture – break that does not penetrate
the skin
 Open (compound) fracture – broken bone
penetrates through the skin
 Bone fractures are treated by reduction and
immobilization
 Realignment of the bone – either by physician’s
hands or surgery
Common Types of Fractures
Table 5.2
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Repair of Bone Fractures
 Hematoma (blood-filled swelling) is formed
due to broken blood vessels
 Break is splinted by fibrocartilage to form a callus –
cartilage matrix, bony matrix, collagen fibers –
capillaries also form again
 Fibrocartilage callus is replaced by a bony callus
made of spongy bone
 Bony callus is remodeled to form a
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Slide 5.17
permanent patch
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Stages in the Healing of a Bone Fracture
The Axial Skeleton
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Education, Inc. publishing as
Slide 5.19
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The Axial Skeleton
 Forms the longitudinal part of the body
 Divided into three parts
 Skull
 Vertebral column
 Bony thorax
The Skull
 Two sets of bones
 Cranium
 Facial bones
 Bones are joined by sutures –
interlocking, immovable joints
 Only the mandible is attached by a freely
movable joint
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as5.21
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The Skull
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Figure 5.7
Bones of the Skull
Figure 5.11
Slide 5.23
Human Skull, Superior View
Figure 5.11
Slide 5.24
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Structure of a Typical Vertebrae
Figure 5.16
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Slide 5.25
Regional Characteristics of Vertebrae
Figure 5.17a, b
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Slide 5.26
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Regional Characteristics of Vertebrae
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Figure 5.17c, d
The Bony Thorax
 Forms a cage
to protect
major organs
Figure 5.19a
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Slide 5.28
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The Appendicular Skeleton
 126 bones of the:
 Limbs (appendages)
 Pectoral girdle
 Pelvic girdle
The Appendicular Skeleton
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Inc. publishing as Benjamin Cummings
Figure 5.6c
Slide 5.30
Bones of the Shoulder Girdle
Figure 5.20a, b
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Slide 5.31
Bones of the Upper Limb
 The arm is
formed by a
single bone
 Humerus
Figure 5.21a, b
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Bones of the Upper Limb
• The forearm has
two bones
• Ulna
• Radius
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Figure 5.21c
Bones of the Upper Limb
 The hand
 Carpals – wrist
 Metacarpals –
palm
 Phalanges –
fingers
Figure 5.22
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Slide 5.34
Bones of the Pelvic Girdle
 Hip bones
 Composed of three pair of fused bones
 Ilium
 Ischium
 Pubic bone
 The total weight of the upper body rests on the pelvis
 Protects several organs
 Reproductive organs
 Urinary bladder
 Part of the large intestine
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Slide 5.35
The Pelvis
Figure 5.23a
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Slide 5.36
The Pelvis
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Figure 5.23b
Slide 5.37
Gender Differences of the Pelvis
Figure 5.23c
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Slide 5.38
Bones of the Lower Limbs
 The thigh has
one bone
 Femur – thigh
bone
 The heaviest and
strongest bone in
the body
Figure 5.35a, b
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Slide 5.39
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Bones of the Lower Limbs
 The leg has two bones
 Tibia
 Fibula
Figure 5.35c
Bones of the Lower Limbs
 The foot
 Tarsus – ankle
 Metatarsals – sole
 Phalanges – toes
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Figure 5.25
Slide 5.41
Arches of the Foot
 Bones of the foot
are arranged to
form three strong
arches
 Two longitudinal
 One transverse
Figure 5.26
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Slide 5.42
Joints
 Articulations of bones
 Functions of joints
 Hold bones together
 Allow for mobility
 Ways joints are classified
 Functionally
 Structurally
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Slide 5.43
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Functional Classification of Joints
 Synarthroses – immovable joints
 Amphiarthroses – slightly moveable
joints
 Diarthroses – freely moveable joints
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Fibrous Joints
 Bones united by fibrous tissue
 Examples
 Sutures in skull
 Syndesmoses
 Allows more movement
than sutures because
fibers are longer
 Example: distal end of
tibia and fibula
Figure 5.27d, e
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Slide 5.45
Cartilaginous Joints
 Bones connected by cartilage
 Examples
 Pubic
symphysis - pelvis
 Intervertebral
joints – spinal column
Figure 5.27b, c
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Synovial Joints
 Articulating bones
are separated by
a joint cavity
 Synovial fluid is
found in the joint
cavity
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Figure 5.27f–h
Slide
5.47
The Synovial Joint
Figure 5.28
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Slide 5.48
Types of Synovial Joints Based on Shape
Figure 5.29a–c
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Slide 5.49
Types of Synovial Joints Based on Shape
Figure 5.29d–f
Slide 5.50
The Muscular System
 Muscles are responsible for all types of body
movement
 Three basic muscle types are found in
the body
 Skeletal muscle
 Cardiac muscle
 Smooth muscle
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Slide 6.51
Characteristics of Muscles
 Muscle cells are elongated (muscle
cell = muscle fiber)
 Contraction of muscles is due to the movement of
myofilaments – the muscle cell equivalent of the
microfilaments of cytoskeletons
 All muscles share some terminology
 Prefix myo refers to muscle
 Prefix mys refers to muscle
 Prefix sarco refers to flesh
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Slide 6.52
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Skeletal Muscle Characteristics
 Most are attached by tendons to bones
 Cells are multinucleate & cigar-shaped
 Striated – have visible banding
 Voluntary – subject to conscious control
 Cells are surrounded and bundled by
connective tissue
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Connective Tissue Wrappings of Skeletal Muscle
 Endomysium –
connective tissue
around single
muscle fiber
 Perimysium –
around a fascicle
(bundle) of fibers
Figure 6.1
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Slide 6.54
Connective Tissue Wrappings of Skeletal Muscle
 Epimysium – covers the
entire skeletal muscle
 Fascia – on the outside
of the epimysium
Figure 6.1
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Skeletal Muscle Attachments
 Epimysium blends into a connective tissue
attachment
 Tendon – cord-like structure
 Aponeuroses – sheet-like structure
 Sites of muscle attachment
 Bones
 Cartilages
 Connective tissue coverings
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Slide 6.56
Smooth Muscle Characteristics
 Has no striations
 Spindle-shaped cells
 Single nucleus
 Involuntary – no
conscious control
 Found mainly in the walls of
hollow organs
– visceral
 Arranged in two sheets or
layers
Figure 6.2a
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Cardiac Muscle Characteristics
 Has striations
 Usually has a
single nucleus
 Joined to another
muscle cell at an
intercalated disc
 Involuntary
 Found only in the
heart
Figure 6.2b
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Slide 6.58
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Function of Muscles
 Produce movement
 Maintain posture
 Stabilize joints
 Generate heat
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Properties of Skeletal Muscle Activity
 Irritability – ability to receive and
respond to a stimulus
 Contractility – ability to shorten when an
adequate stimulus is received
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Nerve Stimulus to Muscles
 Skeletal
muscles must
be stimulated by
a nerve to
contract
 Motor unit
 One neuron
 Muscle cells
stimulated by
that neuron
Figure 6.4a
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Slide 6.61
as Benjamin Cummings
Nerve Stimulus to Muscles
 Neuromuscular
junctions –
association site
of nerve and
muscle
Figure 6.5b
Slide 6.62
Nerve Stimulus to Muscles
 Synaptic cleft –
gap between nerve
and muscle
 Nerve and muscle
do not make
contact
 Area between nerve
and muscle is filled
with interstitial fluid
Figure 6.5b
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Slide 6.63
Contraction of a Skeletal Muscle
 Muscle fiber contraction is “all or none”
 Within a skeletal muscle, not all fibers may be
stimulated during the same interval
 Different combinations of muscle fiber
contractions may give differing responses
 Graded responses – different degrees of skeletal
muscle shortening
 Changing frequency of stimulation
 Changing number of muscle cells stimulated
Slide 6.64
Muscle Response to Strong Stimuli
 Muscle force depends upon the number of
fibers stimulated
 More fibers contracting results in
greater muscle tension
 Muscles can continue to contract unless they
run out of energy
Slide 6.65
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Muscle Fatigue and Oxygen Debt
 When a muscle is fatigued, it is unable to contract
even when stimulated
 The common reason for muscle fatigue is oxygen
debt
 Oxygen must be “repaid” to tissue to remove oxygen
debt
 Oxygen is required to get rid of accumulated lactic
acid
 Increasing acidity (from lactic acid) and lack of ATP
causes the muscle to contract less
Slide 6.66
Types of Muscle Contractions
 Isotonic contractions – “same tone” or tension
 Myofilaments are able to slide past each other
during contractions
 The muscle shortens
 Isometric contractions – “same
measurement” or length
 Tension in the muscles increases
 The muscle is unable to shorten
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Slide 6.67
Muscle Tone
 Some fibers are contracted even in a
relaxed muscle
 Different fibers contract at different times
to provide muscle tone
 The process of stimulating various fibers
is under involuntary control
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Slide 6.68
Effects of Exercise on Muscle
 Results of increased muscle use
 Increase in muscle size
 Increase in muscle strength
 Increase in muscle efficiency
 Muscle becomes more fatigue resistant
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Slide 6.69
Types of Muscles
 Prime mover – muscle with the major responsibility
for a certain movement
 Antagonist – muscle that opposes or reverses a
prime mover
 Synergist – muscle that aids a prime mover in the
same movement and helps prevent rotation or
unwanted movement
 Fixator – stabilizes the origin of a prime mover so all
tension can be used to move the insertion bone
Slide 6.70
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Naming of Skeletal Muscles
 Direction of muscle fibers
 Example: rectus (straight) or oblique (slanted)
 Relative size of the muscle
 Examples: maximus (largest), minimus
(smallest), longus (long)
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Slide 6.71
Naming of Skeletal Muscles
 Location of the muscle
Example: many muscles are named for bones
(e.g., temporalis, which is near the temporal
bone)
 Number of origins
 Example: biceps, triceps, quadriceps
(two, three, or four origins or heads)
Slide 6.72
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Naming of Skeletal Muscles
 Location of the muscle’s origin and insertion
 Example: sterno (on the sternum) cleido
(clavicle) mastoid (on the mastoid process)
 Shape of the muscle
 Example: deltoid (triangular)
 Action of the muscle
 Example: flexor and extensor (flexes or extends a bone)
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Slide 6.51
Muscles and Body Movements
 Movement is
attained due to a
muscle moving
an attached bone
Figure 6.12
Slide 6.74
Muscles and Body Movements
 Muscles are attached
to at least two points
 Origin – attachment
to an immoveable
bone
 Insertion –
attachment to a
movable bone
Figure 6.12
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Slide 6.75
Types of Ordinary Body Movements
 Flexion – brings 2 bones closer together
 Extension – increases distance between 2 bones
 Rotation
 Abduction – moving a limb away from the midline of
the body
 Adduction – moving a limb toward the midline
 Circumduction – combination of all of the above
except rotation
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Special Movements
 Dorsiflexion – lifting the foot
 Plantar flexion – depressing the foot
 Inversion – turn foot inward
 Eversion – turn foot outward
 Supination – hand facing upward
 Pronation – hand facing downward
 Opposition – touching thumb to other fingers
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Slide 6.77
Head and Neck Muscles
Figure 6.14
Trunk Muscles
Figure 6.15
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Deep Trunk and Arm Muscles
Figure 6.16
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Muscles of the Pelvis, Hip, and Thigh
Figure 6.18c
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Slide 6.55
Muscles of the Lower Leg
Figure 6.19
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Slide 6.56
Superficial Muscles: Anterior
Figure 6.20
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Slide 6.57
Superficial Muscles: Posterior
Figure 6.21
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The Digestive System and Body Metabolism
 Digestion
 Breakdown of ingested food
 Absorption of nutrients into the blood
 Metabolism
 Production of cellular energy (ATP)
 Constructive and degradative cellular activities
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Slide 14.1
Organs of the Digestive System
Figure 14.1
Slide 14.2b
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Organs of the Digestive System
 Two main groups
 Alimentary canal – continuous coiled hollow tube
 Accessory digestive organs
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Slide 14.2a
Organs of the Alimentary Canal
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Anus
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Slide 14.3
Mouth (Oral Cavity) Anatomy
 Lips (labia) – protect
the anterior opening
 Cheeks – form the
lateral walls
 Hard palate – forms
the anterior roof
 Soft palate – forms
the posterior roof
 Uvula – fleshy
projection of the
soft palate
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Figure 14.2a
Slide 14.4
Mouth (Oral Cavity) Anatomy
 Vestibule – space between
lips externally and teeth and
gums internally
 Oral cavity – area contained
by the teeth
 Tongue – attached at hyoid
and styloid processes of the
skull, and by the lingual
frenulum
Figure 14.2a
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Slide 14.5
Mouth (Oral Cavity) Anatomy
 Tonsils
 Palatine tonsils
 Lingual tonsil
Figure 14.2a
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Slide 14.6
Processes of the Mouth
 Mastication (chewing) of food
 Mixing masticated food with saliva
 Initiation of swallowing by the tongue
 Allowing for the sense of taste
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Slide 14.7
Pharynx Anatomy
 Nasopharynx –
not part of the digestive system
 Oropharynx – posterior to oral
cavity
 Laryngopharynx – below the
oropharynx and connected to
the esophagus
Figure 14.2a
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Slide 14.8
Pharynx Function
 Serves as a passageway for air and food
 Food is propelled to the esophagus by two muscle
layers
 Longitudinal inner layer
 Circular outer layer
 Food movement is by alternating contractions of the
muscle layers (peristalsis)
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Slide 14.9
Esophagus
 Runs from pharynx to stomach through the diaphragm
 Conducts food by peristalsis
(slow rhythmic squeezing)
 Passageway for food only (respiratory system
branches off after the pharynx)
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Slide 14.10
Layers of Alimentary Canal Organs
 Mucosa
 Submucosa
 Innermost layer
 Just beneath the mucosa
 Moist membrane
 Soft connective tissue
with blood vessels, nerve
endings, and lymphatics
 Surface epithelium
 Small amount of connective
tissue
(lamina propria)
 Small smooth muscle layer
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Slide 14.11a
Specialized Mucosa of the Stomach
 Simple columnar epithelium
 Mucous neck cells – produce a sticky alkaline mucus
 Gastric glands – secrete gastric juice
 Chief cells – produce protein-digesting enzymes
(pepsinogens)
 Parietal cells – produce hydrochloric acid
 Endocrine cells – produce gastrin
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Slide 14.19
Layers of Alimentary Canal Organs
 Muscularis externa – smooth muscle
 Inner circular layer
 Outer longitudinal layer
 Serosa
 Outermost layer – visceral peritoneum
 Layer of serous fluid-producing cells
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Slide 14.11b
Structure of the Stomach Mucosa
 Gastric pits
formed by folded
mucosa
 Glands and
specialized cells
are in the gastric
gland region
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Slide 14.20a
Layers of Alimentary Canal Organs
Figure 14.3
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Slide 14.13
Alimentary Canal Nerve Plexuses
 All are part of the autonomic nervous system
 Three separate networks of nerve fibers
 Submucosal nerve plexus
 Myenteric nerve plexus
 Subserous plexus
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Slide 14.14
Stomach Anatomy
 Located on the left side of the abdominal
cavity
 Food enters at the cardioesophageal
sphincter
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Slide 14.15a
Stomach Functions
 Acts as a storage tank for food
 Site of food breakdown
 Chemical breakdown of protein begins
 Delivers chyme (processed food) to the small
intestine
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Slide 14.18
Stomach Functions
 Regions of the stomach
 Cardiac region – near the heart
 Fundus
 Body
 Pylorus – funnel-shaped terminal end
 Food empties into the small intestine at the
pyloric sphincter
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Slide 14.18
Stomach Anatomy
 Rugae – internal folds of the mucosa
 External regions
 Lesser curvature
 Greater curvature
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Slide 14.16a
Stomach Anatomy
 Layers of peritoneum attached to the stomach
 Lesser omentum – attaches the liver to the lesser curvature
 Greater omentum – attaches the greater curvature to the
posterior body wall
 Contains fat to insulate, cushion, and protect abdominal
organs
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Slide 14.16b
Stomach Anatomy
Figure 14.4a
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Slide 14.17
Small Intestine
 The body’s major digestive organ
 Site of nutrient absorption into the blood
 Muscular tube extending form the pyloric sphincter to
the ileocecal valve
 Suspended from the posterior abdominal wall by the
mesentery
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Slide 14.21
Subdivisions of the Small Intestine
 Duodenum
 Attached to the stomach
 Curves around the head of the pancreas
 Jejunum
 Attaches anteriorly to the duodenum
 Ileum
 Extends from jejunum to large intestine
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Slide 14.22
Chemical Digestion in the Small Intestine
 Source of enzymes that are mixed with chyme
Intestinal cells
Pancreas
 Bile enters from the gall bladder
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Slide 14.23a
Chemical Digestion in the Small Intestine
Figure 14.6
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Slide 14.23b
Villi of the Small Intestine
 Fingerlike structures
formed by the mucosa
 Give the small intestine
more surface area
Figure 14.7a
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Slide 14.24
Microvilli of the Small Intestine
 Small projections of the
plasma membrane
 Found on absorptive cells
Figure 14.7c
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Slide 14.25
Structures Involved in Absorption of Nutrients
 Absorptive cells
 Blood capillaries
 Lacteals (specialized
lymphatic capillaries)
Figure 14.7b
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Slide 14.26
Folds of the Small Intestine
 Called circular folds or plicae circulares
 Deep folds of the mucosa and submucosa
 Do not disappear when filled with food
 The submucosa has Peyer’s patches (collections of
lymphatic tissue)
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Slide 14.27
Large Intestine
 Larger in
diameter, but
shorter than the
small intestine
 Frames the
internal
abdomen
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Functions of the Large Intestine
 Absorption of water
 Eliminates indigestible food from the body as feces
 Does not participate in digestion of food
 Goblet cells produce mucus to act as a lubricant
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Slide 14.29
Structures of the Large Intestine
 Cecum – saclike first part of the large intestine
 Appendix
Accumulation of lymphatic tissue that sometimes
becomes inflamed (appendicitis)
Hangs from the cecum
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Slide 14.30a
Structures of the Large Intestine
 Colon
 Ascending
 Transverse
 Descending
 S-shaped sigmoidal
 Rectum
 Anus – external body opening
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Slide 14.30b
Modifications to the Muscularis Externa in the
Large Intestine
 Smooth muscle is reduced to three bands (teniae
coli)
 Muscle bands have some degree of tone
 Walls are formed into pocketlike sacs called haustra
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Slide 14.31
Accessory Digestive Organs
 Salivary glands
 Teeth
 Pancreas
 Liver
 Gall bladder
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Slide 14.32
Salivary Glands
 Saliva-producing glands
 Parotid glands – located anterior to ears
 Submandibular glands
 Sublingual glands
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Slide 14.33
Saliva
 Mixture of mucus and serous fluids
 Helps to form a food bolus
 Contains salivary amylase to begin starch digestion
 Dissolves chemicals so they can be tasted
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Slide 14.34
Teeth
 The role is to masticate
(chew) food
 Humans have two sets
of teeth
 Deciduous (baby or milk)
teeth
 20 teeth are fully formed
by age two
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 Permanent teeth
 Replace deciduous
teeth beginning
between the ages of 6
to 12
 A full set is 32 teeth,
but some people do not
have wisdom teeth
Slide 14.35a
Classification of Teeth
Figure 14.9
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Slide 14.36b
Regions of a Tooth
 Crown – exposed part
 Outer enamel
 Dentin
 Pulp cavity
 Neck
 Region in contact with the
gum
 Connects crown to root
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Figure 14.10
Slide 14.37a
Regions of a Tooth
 Root
 Periodontal membrane
attached to the bone
 Root canal carrying
blood vessels and
nerves
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Figure 14.10
Slide 14.37b
Pancreas
 Produces a wide spectrum of digestive enzymes that break
down all categories of food
 Enzymes are secreted into the duodenum
 Alkaline fluid introduced with enzymes neutralizes acidic chyme
 Endocrine products of pancreas
 Insulin
 Glucagons
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Slide 14.38
Liver
 Largest gland in the body
 Located on the right side of the body under the
diaphragm
 Consists of four lobes suspended from the diaphragm
and abdominal wall by the falciform ligament
 Connected to the gall bladder via the common hepatic
duct
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Slide 14.39
Bile
 Produced by cells in the liver
 Composition
 Bile salts
 Bile pigment (mostly bilirubin from the breakdown of
hemoglobin)
 Cholesterol
 Phospholipids
 Electrolytes
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Slide 14.40
Gall Bladder
 Sac found in hollow fossa of liver
 Stores bile from the liver by way of the cystic duct
 Bile is introduced into the duodenum in the presence
of fatty food
 Gallstones can cause blockages
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Slide 14.41
The Senses
 General senses of touch (tactile)
 Temperature- thermoreceptors (heat)
 Pressure- mechanoreceptors (movement)
 Pain- mechanoreceptors
 Special senses
 Smell- chemoreceptors (chemicals)
 Taste- chemoreceptors
 Sight- photoreceptors (light)
 Hearing- mechanoreceptors
 Equilibrium- (balance) mechanoreceptors
The Eye and Vision
 70 percent of all sensory receptors are in the eyes
 Each eye has over a million nerve fibers
 Protection for the eye
 Most of the eye is enclosed in a bony orbit made up of the
lacrimal (medial), ethmoid (posterior), sphenoid (lateral),
frontal (superior), and zygomatic and maxilla (inferior)
 A cushion of fat surrounds most of the eye
Accessory Structures of the Eye
 Eyelids - brush particles out of eye or cover eye
 Eyelashes - trap particles and keep them out of the eye
 Ciliary glands – modified sweat glands between the
eyelashes
- secrete acidic sweat to kill bacteria,
lubricate eyelashes
Accessory Structures of the Eye
Accessory Structures of the Eye
 Conjunctiva
 Membrane that
lines the eyelids
 Connects to the
surface of the
eye- forms a
seal
 Secretes mucus
to lubricate the
eye
http://neuromedia.neurobio.ucla.edu/campbell/eyeandear/wp_images/175_conjunctiva.gif
Accessory Structures of the Eye
 Lacrimal apparatus
 Lacrimal gland – produces
lacrimal fluid
 Lacrimal canals – drains
lacrimal fluid from eyes
 Lacrimal sac – provides
passage of lacrimal fluid
towards nasal cavity
 Nasolacrimal duct –
empties lacrimal fluid into
the nasal cavity
Function of the Lacrimal Apparatus
 Properties of lacrimal fluid
 Dilute salt solution (tears)
 Contains antibodies (fight antigens- foreign substance) and
lysozyme (enzyme that destroys bacteria)
 Protects, moistens, and lubricates the eye
 Empties into the nasal cavity
Extrinsic Eye Muscles
 Muscles attach to the outer surface of the eye
 Produce eye movements
When Extrinsic Eye Muscles Contract
 Superior oblique- eyes look out and down
 Superior rectus- eyes looks up
 Lateral rectus- eyes look outward
 Medial rectus- eyes look inward
 Inferior rectus- eyes looks down
 Inferior oblique- eyes look in and up
Structure of the Eye
 The wall is composed
of three tunics
 Fibrous tunic – outside
layer
 Choroid – middle layer
 Sensory tunic – inside
layer
The Fibrous Tunic
 Sclera
 White connective tissue layer
 Seen anteriorly as the “white of the eye”
 Semi-transparent
The Fibrous Tunic
 Cornea
 Transparent, central
anterior portion
 Allows for light to pass
through (refracts, or
bends, light slightly)
 Repairs itself easily
 The only human tissue
that can be transplanted
without fear of rejection
Choroid Layer
 Blood-rich nutritive tunic
 Pigment prevents light from scattering (opaqueblocks light from getting in, has melanin)
Choroid Layer
 Modified interiorly into two structures
 Cilliary body – smooth muscle (contracts to adjust the shape
of the lens)
 Iris- pigmented layer that gives eye color (contracts to adjust
the size of the pupil- regulates entry of light into the eye)
 Pupil – rounded opening in the iris
Sensory Tunic (Retina)
 Contains receptor cells
(photoreceptors)
 Rods
 Cones
 Signals leave the retina
toward the brain through the
optic nerve
Sensory Tunic (Retina)
 Signals pass from photoreceptors via a two-neuron
chain
 Bipolar neurons and Ganglion cells
Neurons of the Retina and Vision
 Rods
 Most are found towards the edges of the retina
 Allow dim light vision and peripheral vision (more sensitive
to light, do not respond in bright light)
 Perception is all in gray tones
ROD CELLS
http://webvision.med.utah.edu/imageswv/rod-GC.jpeg
http://www.webvision.med.utah.edu/imageswv/PKCrodb.jpeg
Neurons of the Retina and Vision
 Cones
 Allow for detailed color vision
 Densest in the center of the retina
 Fovea centralis – area of the retina with only cones
 Respond best in bright light
 No photoreceptor cells are at the optic disk, or
blind spot
Cone Sensitivity
• There are three types of
cones
• Different cones are
sensitive to different
wavelengths
- red- long
- green- medium
- blue- short
• Color blindness is the
result of lack of one or
more cone type
Lens
 Biconvex crystal-like
structure
 Held in place by a
suspensory
ligament attached to
the ciliary body
 Refracts light
greatly
Internal Eye Chamber Fluids
 Aqueous humor
 Watery fluid found in chamber
between the lens and cornea
 Similar to blood plasma
 Helps maintain intraocular
pressure
 Provides nutrients for the lens
and cornea
 Reabsorbed into venous blood
through the canal of Schlemm
Refracts light
slightly
Internal Eye Chamber Fluids
 Vitreous humor
 Gel-like substance behind the lens
 Keeps the eye from collapsing
 Lasts a lifetime and is not replaced
http://faculty.washington.edu/kepeter/119/images/eye3.jpg
Refracts light
slightly
Holds lens and
retina in place
Lens Accommodation
 Light must be focused to a point
on the retina for optimal vision
 The eye is set for distance
vision
(over 20 ft away)
 20/20 vision- at 20 feet, you see
what a normal eye would see at
20 feet (20/100- at 20, normal
person would see at 100)
 The lens must change shape to
focus for closer objects
Images Formed on the Retina
If the image is focused at the spot where the optic disk is
located, nothing will be seen. This is known as the blind spot.
There are no photoreceptors there, as nerves and blood vessels
pass through this point.
Visual Pathway
 Photoreceptors of the
retina
 Optic nerve
 Optic nerve crosses at
the optic chiasma
Visual Pathway
 Optic tracts
 Thalamus (axons form
optic radiation)
 Visual cortex of the
occipital lobe
Eye Reflexes
 Internal muscles are controlled by the autonomic
nervous system
 Bright light causes pupils to constrict through action of
radial (iris) and ciliary muscles
 Viewing close objects causes accommodation
 External muscles control eye movement to follow
objects- voluntary, controlled at the frontal eye field
 Viewing close objects causes convergence (eyes
moving medially)
The Ear
 Houses two senses
 Hearing (interpreted in the auditory cortex of the
temporal lobe)
 Equilibrium (balance) (interpreted in the cerebellum)
 Receptors are mechanoreceptors
 Different organs house receptors for each sense
Anatomy of the Ear
 The ear is divided into
three areas
 Outer (external) ear
 Middle ear
 Inner ear
The External Ear
 Involved in hearing
only
 Structures of the
external ear
 Pinna (auricle)collects sound
 External auditory canalchannels sound
inward
The External Auditory Canal
 Narrow chamber in the temporal bone- through the
external auditory meatus
 Lined with skin
 Ceruminous (wax) glands are present
 Ends at the tympanic membrane (eardrum)
The Middle Ear or Tympanic Cavity
 Air-filled cavity within the temporal bone
 Only involved in the sense of hearing
 Two tubes are associated with the inner ear
 The opening from the auditory canal is covered by the tympanic
membrane (eardrum)
 The auditory tube connecting the middle ear with the throat
(also know as the eustacian tube)
 Allows for equalizing pressure during yawning or swallowing
 This tube is otherwise collapsed
Bones of the Tympanic Cavity
 Three bones span
the cavity
 Malleus (hammer)
 Incus (anvil)
 Stapes (stirrup)
Bones of the Tympanic Cavity
 Vibrations from
eardrum move the
malleus
 These bones
transfer sound to
the inner ear
Inner Ear or Bony Labyrinth
 Also known as
osseous labyrinthtwisted bony tubes
 Includes sense
organs for hearing
and balance
 Filled with perilymph
Inner Ear or Bony Labyrinth
•
Vibrations of the stapes
push and pull on the
membranous oval
window, moving the
perilymph through the
cochlea. The round
window is a membrane
at the opposite end to
relieve pressure.
Inner Ear or Bony Labryinth
 A maze of bony chambers
within the temporal bone
 Cochlea
 Upper chamber
is the scala
vestibuli
 Lower chamber
is the scala
tympani
 Vestibule
 Semicircular
canals
Organ of Corti
 Located within the cochlea
 Receptors = hair cells on the basilar membrane
 Gel-like tectorial membrane is capable of bending hair cells
(endolymph in the membranous labyrinth of the cochlear
duct flows over it and pushes on the membrane)
 Cochlear nerve attached to hair cells transmits nerve impulses
to auditory cortex on temporal lobe
Organs of Hearing
Scala vestibuli
Scala tympani
Mechanisms of Hearing
 Vibrations from sound
waves move tectorial
membrane (pass
through the endolymph
fluid filling the
membranous labyrinth
in the cochlear duct)
 Hair cells are bent by the
membrane
Mechanisms of Hearing
 An action potential starts in the
cochlear nerve
 The signal is transmitted to the
midbrain (for auditory reflexes
and then directed to the auditory
cortex of the temporal lobe)
 Continued stimulation can lead to
adaptation (over stimulation to
the brain makes it stop
interpreting the sounds)
Organs of Equilibrium
 Receptor cells are in two structures
 Vestibule
 Semicircular canals
 Equilibrium has two functional parts
 Static equilibrium- in the vestibule
 Dynamic equilibrium- in the semicircular canals
Organs of Equilibrium
Chemical Senses – Taste and Smell
 Both senses use chemoreceptors
 Stimulated by chemicals in solution
 Taste has four types of receptors
 Smell can differentiate a large range of chemicals
 Both senses complement each other and respond to
many of the same stimuli
Olfaction – The Sense of Smell
 Olfactory receptors are in
the roof of the nasal cavity
 Neurons with long cilia
 Chemicals must be
dissolved in mucus for
detection
 Impulses are transmitted
via the olfactory nerve
 Interpretation of smells is
made in the cortex
(olfactory area of
temporal lobe)
The Sense of Taste
 Taste buds house
the receptor
organs
 Location of taste
buds
 Most are on the
tongue
 Soft palate
 Cheeks
The Tongue and Taste
 The tongue is covered with
projections called papillae
 Filiform papillae – sharp with
no taste buds
 Fungifiorm papillae – rounded
with taste buds
 Circumvallate papillae – large
papillae with taste buds
 Taste buds are found on the
sides of papillae
Structure of Taste Buds
 Gustatory cells are the receptors
 Have gustatory hairs (long microvilli)
 Hairs are stimulated by chemicals dissolved in saliva
 Impulses are carried to the gustatory complex (pareital lobe) by
several cranial nerves because taste buds are found in different
areas
 Facial nerve
 Glossopharyngeal nerve
 Vagus nerve
Structure of Taste Buds
Taste Sensations
 Sweet receptors
 Sugars
 Saccharine
 Some amino acids
 Sour receptors
 Acids
 Bitter receptors
 Alkaloids
 Salty receptors
 Metal ions
 Umami
 Glutamate, aspartate (MSG, meats)
http://instruct1.cit.cornell.edu/courses/psych431/student2000/mle6/tonguebig.gif
Developmental Aspects of the Special Senses
 Formed early in embryonic development
 Eyes are outgrowths of the brain
 All special senses are functional at birth
The Nervous System
Functions of the Nervous System
 Sensory input – gathering information
 To monitor changes occurring inside and outside the body
 Changes = stimuli
 Integration
 To process and interpret sensory input and decide if action is
needed
 Motor output
 A response to integrated stimuli
 The response activates muscles or glands
Slide 7.186
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Structural Classification of the Nervous System
 Central nervous system (CNS)
 Brain and Spinal cord
 Acts as integrating and command center – interpret incoming
sensory information and issue instructions
based on past experiences and current conditions
 Peripheral nervous system (PNS)
 Nerves outside the brain and spinal cord
 Link all parts of the body by carrying impulses to the CNS and back
Slide 7.187
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Functional Classification of the Peripheral Nervous System
 Sensory (afferent) division
 Nerve fibers that carry information to the central
nervous system
Figure 7.1
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Slide 7.188
Functional Classification of the Peripheral Nervous System
 Motor (efferent) division
 Nerve fibers that carry impulses away from the central nervous
system
Figure 7.1
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Slide
7.189
Functional Classification of the Peripheral Nervous System
 Motor (efferent) division
 Two subdivisions
 Somatic nervous system = voluntary nervous
system
 Skeletal muscle reflexes such as stretch
reflex are initiated involuntarily by same fibers
 Autonomic nervous system = involuntary nervous
system
 Sympathetic and parasympathetic divisions
Copyright © 2003 Pearson Education, Inc. publishing as
Benjamin Cummings
Slide 7.6
Organization of the Nervous System
Figure 7.2
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Nervous Tissue: Neurons
 Neurons = nerve cells
 Cells specialized to transmit messages
 Major regions of neurons
 Cell body – nucleus and metabolic center of the cell
 Processes – fibers that extend from the cell body
Slide 7.192
Neuron Anatomy
 Cell body
 Nissl substance –
specialized rough
endoplasmic
reticulum
 Neurofibrils –
intermediate
cytoskeleton that
maintains cell
shape
Figure 7.4a
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as7.193
Slide
Benjamin Cummings
Neuron Anatomy
 Cell body
 Nucleus
 Large nucleolus
 Extensions outside the cell
body
 Dendrites – conduct
impulses toward the cell
body
 Axons – conduct impulses
away from the cell body
Copyright © 2003 Pearson Education, Inc. publishing as
Figure 7.4a
Slide 7.194
Axons and Nerve Impulses
 Axons end in axonal terminals
 Axonal terminals contain vesicles with
neurotransmitters
 Axonal terminals are separated from the next neuron
by a gap
 Synaptic cleft – gap between adjacent neurons
 Synapse – junction between nerves
Slide 7.195
Nerve Fiber Coverings
 Schwann cells –
produce myelin sheaths
in jelly-roll
 Nodes of Ranvier – gaps
in myelin sheath along
the axon
Figure 7.5
Slide
7.196
Neuron Cell Body Location
 Most are found in the central nervous system in
clusters called nuclei
 Bundles of nerve fibers in CNS = tracts
 Gray matter – cell bodies and
unmyelinated fibers
 White matter – myelinated fibers
 Bundles of nerve fibers in PNS = nerves
 Ganglia – collections of cell bodies outside the central
nervous system
Functional Classification of Neurons
 Sensory (afferent) neurons
 Cell bodies in a ganglion outside the CNS
 Carry impulses from the sensory receptors to CNS
 Cutaneous (skin) sense organs
 Proprioceptors – detect stretch or tension in muscles,
tendons, joints
 Motor (efferent) neurons
 Cell bodies found in the CNS
 Carry impulses from the central nervous system
Slide 7.198
Neuron Classification
Figure 7.6
Structural Classification of Neurons
 Multipolar neurons – many extensions from the
cell body
Figure 7.8a
Slide 7.200
Structural Classification of Neurons
 Bipolar neurons – one axon and one dendrite
 Rare in adults – in eye and ear only
Figure 7.8b
Slide 7.201
Structural Classification of Neurons
 Unipolar neurons – have a short, single process leaving
the cell body
 Axon conducts nerve impulses both to and from the cell body
Figure 7.8c
Slide 7.202
Continuation of the Nerve Impulse between Neurons
 Impulses are unable to cross the synapse to another
nerve
 Neurotransmitter is released from a nerve’s axon terminal
 The dendrite of the next neuron has receptors that are
stimulated by the neurotransmitter
 An action potential is started in the dendrites of the next
neuron
 Transmission of an impulse is an electrochemical event
Slide 7.203
Functional Classification of Neurons
 Interneurons (association neurons)
 Found in neural pathways in the central nervous
system
 Cell bodies in the CNS
 Connect sensory and motor neurons
Slide 7.204
Functional Properties of Neurons
 Two main functions
 Irritability – ability to respond to stimuli
 Conductivity – ability to transmit an impulse
 The plasma membrane at rest is polarized
 Fewer positive ions (usually K+) are inside the cell than
outside the cell (usually Na+)
Slide 7.205
The Reflex Arc
 Reflex – rapid, predictable, and involuntary
responses to stimuli
 Reflex arc – direct route from a sensory neuron, to an
interneuron, to an effector
Copyright © 2003 Pearson Education, Inc. publishing as
Figure
7.11a
Slide
7.206
Simple Reflex Arc
Figure 7.11b, c
Slide 7.207
Types of Reflexes and Regulation
 Autonomic reflexes
 Smooth muscle regulation
 Size of eye pupils
 Heart and blood pressure regulation
 Regulation of glands and sweating
 Digestive system and elimination regulation
 Somatic reflexes
 Activation of skeletal muscles
Slide 7.208
Types of Reflexes and Regulation
 Reflex arcs have a minimum five elements
 A sensory receptor – reacts to stimuli
 An effector receptor – muscle or gland
stimulated
 Afferent and efferent neurons connecting the two
 The CNS integration center
Slide 7.209
Central Nervous System (CNS)
 CNS develops from the embryonic neural tube – a
simple tube
 The neural tube becomes the brain and spinal cord
 The opening of the neural tube becomes the ventricles
 Four chambers within the brain
 Filled with cerebrospinal fluid
Slide 7.210
Regions of the Brain
 Cerebral hemispheres
 Diencephalon
 Brain stem
 Cerebellum
Figure 7.12
Slide 7.211
Cerebral Hemispheres (Cerebrum)
 Paired (left and
right) superior
parts of the brain
 Include more
than half of the
brain mass
Figure
7.13a
Slide
7.212
Cerebral Hemispheres (Cerebrum)
 The surface is
made of:
 Gyri - elevated
ridges
 Sulci - shallow
grooves
Figure
7.13a
Slide
7.213
Lobes of the Cerebrum
 Fissures (deep grooves) divide the
cerebrum into lobes
 Surface lobes of the cerebrum – named for cranial
bone over them
 Frontal lobe
 Parietal lobe
 Occipital lobe
 Temporal lobe
Slide 7.214
Lobes of the Cerebrum
Figure 7.15a
Slide 7.215
Sensory and Motor Areas of the Cerebral Cortex
Figure 7.14
Slide
7.216
Specialized Areas of the Cerebrum
 Somatic sensory area in parietal lobe – receives
impulses from the body’s sensory receptors
(except special senses)
 Occipital lobe – vision and temporal lobe
– auditory
 Primary motor area – sends impulses to skeletal
muscles – frontal lobe
 Broca’s area – involved in our ability to speak –
base of the precentral gyrus
Slide 7.217
Specialized Area of the Cerebrum
Cerebral areas involved in special senses
Gustatory area (taste)
Visual area
Auditory area
Olfactory area
Interpretation areas of the cerebrum
Speech/language region
Language comprehension region
General interpretation area
Slide 7.218
Specialized Area of the Cerebrum
Figure 7.13c
Layers of the Cerebrum
 Gray matter
 Outermost layer
 Composed mostly of
neuron cell bodies
 Cerebral cortex
Figure 7.13a
Slide
7.220
Layers of the Cerebrum
 White matter
 Fiber tracts inside
the gray matter
 Example: corpus
callosum connects
hemispheres
Figure 7.13a
Layers of the Cerebrum
 Basal nuclei –
internal islands of
gray matter
 Helps regulate
voluntary motor
activities by
modifying
instructions sent to
the skeletal muscles
Figure 7.13a
Slide
7.222
Diencephalon - interbrain
 Sits on top of the brain stem
 Enclosed by the cerebral hemispheres
 Made of three parts
 Thalamus
 Hypothalamus
 Epithalamus
Slide 7.223
Diencephalon
Figure 7.15
Slide 7.224
Thalamus
 Surrounds the third ventricle of the brain
 The relay station for sensory impulses passing
upward to the sensory cortex
 Transfers impulses to the correct part of the cortex
for localization and interpretation
Slide 7.225
Hypothalamus
 Under the thalamus
 Important autonomic nervous system center
 Helps regulate body temperature
 Controls water balance
 Regulates metabolism
 An important part of the limbic system (emotions) – emotionalvisceral brain
 The pituitary gland is attached to and regulated by the
Slide 7.226
hypothalamus
Epithalamus
 Forms the roof of the third ventricle
 Houses the pineal body (an endocrine gland)
 Includes the choroid plexus – forms cerebrospinal
fluid
Slide 7.227
Brain Stem
 Attaches to the spinal cord
 Parts of the brain stem
 Midbrain
 Pons
 Medulla oblongata
Slide 7.228
Brain Stem
Figure 7.15a
Midbrain
 Mostly composed of tracts of nerve fibers
 The cerebral aqueduct – canal that connects the 3rd
ventricle of the diencephalon to the 4th ventricle
 Has two bulging fiber tracts – cerebral peduncles –
convey ascending and descending impulses
 Has four rounded protrusions – corpora
quadrigemina – Reflex centers for vision and hearing
Slide 7.230
Pons
 The bulging center part of the brain stem
 Mostly composed of fiber tracts
 Includes nuclei involved in the control of
breathing
Slide 7.231
Medulla Oblongata




The lowest part of the brain stem
Merges into the spinal cord
Includes important fiber tracts
Contains important control centers
 Heart rate control
 Blood pressure regulation
 Breathing
 Swallowing
 Vomiting
Slide 7.232
Cerebellum
 Two hemispheres with convoluted
surfaces
 Provides involuntary coordination of body
movements – of skeletal muscles, balance and
equilibrium
 Automatic pilot – continually comparing brain’s
intentions with actual body performance
Slide 7.233
Cerebellum
Figure 7.15a
Protection of the Central Nervous System
 Scalp and skin
 Cerebrospinal
fluid
 Skull and
vertebral
 Blood brain
barrier column
 Meninges
Figure 7.16a
Meninges
 Dura mater
 Double-layered external covering the brain
 Periosteum – attached to surface of the skull
 Meningeal layer – outer covering of the brain and
continues as the dura matter of the spinal cord
Folds inward in several areas that
attaches the brain to cranial cavity
Meninges
 Arachnoid layer
 Middle layer that is web-like
 Pia mater
 Internal layer that clings to the surface of the brain
following every fold
 Subarachnoid space filled with cerebrospinal fluid
 Arachnoid villi – projections of arachnoid membrane
protruding through the dura matter
Slide 7.237
Cerebrospinal Fluid
 Similar to blood plasma composition
 Less protein, more vitamin C, different ions
 Formed by the choroid plexus
 Forms a watery cushion to protect the brain
 Circulated in arachnoid space, ventricles, and
central canal of the spinal cord
Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17a
Ventricles and Location of the Cerebrospinal Fluid
Figure 7.17b
Blood Brain Barrier
 Includes the least permeable capillaries of the body –
only H2O, glucose, and essential amino acids get through
 Excludes many potentially harmful
substances
 Useless against some substances
 Fats and fat soluble molecules
 Respiratory gases
 Alcohol
 Nicotine
 Anesthesia
Spinal Cord
 Extends from the
medulla oblongata to
the region of T12
 Below T12 is the cauda
equina (a collection of
spinal nerves)
 Enlargements occur in
the cervical and lumbar
regions
Figure 7.18
Slide 7.242
Spinal Cord Anatomy
 Internal gray matter - mostly cell bodies that
surround the central canal of the cord
 Dorsal (posterior) horns
 Anterior (ventral) horns
 Contains motor neurons of the somatic nervous
system, which send their axons out the ventral root
 Together they fuse to form the spinal nerves
 Nerves leave at the level of each vertebrae
Spinal Cord Anatomy
 Cell bodies of sensory neurons, whose fibers enter the
cord by the dorsal root, are found in an enlarged area
called the dorsal root ganglion
 Damage to this area causes sensation from the body area
served to be lost
Figure 7.19
Slide 7.244
Spinal Cord Anatomy
 Exterior white mater – conduction tracts
 Posterior, lateral, and anterior columns
 Each contains a number of fiber tracts make up of
axons with the same destination and function
Figure 7.19
Copyright © 2003 Pearson Education, Inc. publishing as
Spinal Cord Anatomy
 Central canal filled with cerebrospinal fluid
Figure 7.19
Peripheral Nervous System
 Nerves and ganglia outside the central
nervous system
 Nerve = bundle of neuron fibers
 Neuron fibers are bundled by a
connective tissue sheath
Cranial Nerves
 12 pairs of nerves that mostly serve the head and neck
 Numbered in order, front to back – names reveal structures
they control
 Most are mixed nerves, but three are sensory only
 Optic, olfactory, and vestibulocochlear
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 7.248
Distribution of
Cranial Nerves
Figure 7.21
Slide 7.249
Cranial Nerves
 I Olfactory nerve – sensory for smell
 II Optic nerve – sensory for vision
 III Oculomotor nerve – motor fibers to eye muscles
 IV Trochlear – motor fiber to eye muscles
 V Trigeminal nerve – sensory for the face; motor fibers to chewing
muscles
 VI Abducens nerve – motor fibers to eye muscles
 VII Facial nerve – sensory for taste; motor fibers to the face
 VIII Vestibulocochlear nerve – sensory for balance and hearing
Cranial Nerves
 IX Glossopharyngeal nerve – sensory for taste;
motor fibers to the pharynx
 X Vagus nerves – sensory and motor fibers for
pharynx, larynx, and viscera
 XI Accessory nerve – motor fibers to neck and
upper back
 XII Hypoglossal nerve – motor fibers to tongue
Slide 7.251
Spinal Nerves
 There is a pair of spinal nerves at the level of
each vertebrae for a total of 31 pairs
 Spinal nerves are formed by the combination
of the ventral and dorsal roots of the spinal
cord
 Spinal nerves are named for the region from
which they arise
Spinal Nerves
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.22a
Anatomy of Spinal Nerves
 Spinal nerves divide soon
after leaving the spinal
cord
 Dorsal rami – serve the
skin and muscles of the
posterior trunk
 Ventral rami – forms a
complex of networks
(plexus) for the anterior,
which serve the motor and
sensory needs of the limbs
Figure 7.22b
Slide 7.254
Examples of Nerve Distribution
Figure 7.23
Copyright © 2003 Pearson Education, Inc. publishing as
Slide 7.255
Autonomic Nervous System
 The involuntary branch of the nervous system
 Consists of only motor nerves
 Divided into two divisions
 Sympathetic division – mobilizes the body
 Parasympathetic division – allows body to unwind
Anatomy of the Parasympathetic Division
 Originates from the brain stem and S2 – S4
 Neurons in the cranial region send axons out in cranial
nerves to the head and neck organs
 They synapse with the second motor neuron in a
terminal ganglion
 Terminal ganglia are at the effector organs
 Always uses acetylcholine as a
neurotransmitter
Anatomy of the Sympathetic Division –
thoracolumbar division
 Originates from T1 through L2
 Preganglionic axons leave the cord in the ventral root, enter the
spinal nerve, then pass through a ramus communications, to enter
a sympathetic chain ganglion at the sympathetic chain (trunk)
(near the spinal cord)
 Short pre-ganglionic neuron and long postganglionic neuron
transmit impulse from CNS to the effector
 Norepinephrine and epinephrine are neurotransmitters to the
effector organs
Slide 7.258
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Sympathetic Pathways
Figure 7.26
Anatomy of the Autonomic Nervous System
Figure 7.25
Copyright © 2003 Pearson Education, Inc. publishing as
Autonomic Functioning
 Sympathetic – “fight-or-flight”
 Response to unusual stimulus
 Takes over to increase activities
 Remember as the “E” division = exercise,
excitement, emergency, and embarrassment
Slide 7.261
Copyright © 2003 Pearson Education, Inc. publishing as
Autonomic Functioning
 Parasympathetic – housekeeping activites
 Conserves energy
 Maintains daily necessary body functions
 Remember as the “D” division - digestion, defecation,
and diuresis
Copyright © 2003 Pearson Education, Inc. publishing as
Development Aspects of the Nervous System
 The nervous system is formed during the first month of embryonic
development
 Any maternal infection can have extremely harmful effects
 The hypothalamus is one of the last areas of the brain to develop –
contains centers for regulating body temperature
 No more neurons are formed after birth, but growth and maturation
continues for several years largely due to myelination
 The brain reaches maximum weight as a young adult