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Ch 36
Skeletal, Muscular, and
Integumentary Systems
I. The Skeletal System
A. Purpose
1. structural support
a. hydrostatic
1) soft bodied invertebrates
b. exoskeleton
1) arthropods
c. endoskeleton
1) mammals
2. protects internal organs
3. provides for movement
4. stores mineral reserves
5. provides a site for blood cell
formation (only in some bones)
B. The Skeleton
1. 206 bones in adult humans
2. Axial skeleton
a. skull
b. vertebral column
c. rib cage
3. Appendicular skeleton
a. arms
b. legs
c. pelvis
d. shoulder/pectoral girdle
C. Structure of Bones
1. solid network of living cells and
protein fibers that are surrounded by
deposits of calcium salts
2. osteocytes – mature bone cells
3. Ca and P – maintain levels in blood
to support metabolic activities
4. compact bone
a. resists mechanical shock
b. Haversian canals
1) contains blood vessels
Spongy bone
Compact bone
The Structure of
Bone
Haversian
canal
Periosteum
Compact
bone
Bone
marrow
Spongy bone
Osteocyte
Artery
Periosteum
Vein
5. Periosteum
a. protective covering
6. spongy bone
a. add strength w/o lots of mass
b. red marrow
1) site of blood formation
c. yellow marrow
1) fatty area providing
protection
2) converts to red marrow if
needed
D. Development of Bone
1. cartilage
a. includes network of protein fibers
including collagen and elastin
b. embryo starts with cartilage then
later turns to bone
c. does not contain blood vessels
d. relies on diffusion to obtain
nutrients
2. ossification
a. cartilage is replaced by bone
3. long bones have growth plates at
both ends until early 20’s or late teens
E. Types of Joints
1. Immovable Joints or Fibrous
a. fixed
b. ie – bones in skull
2. Slightly Movable or Cartilaginous
a. between tibia and fibula
b. between vertebrae
3. Freely Movable or Synovial Joints
a. Ball-and-Socket (shoulder)
b. Hinge (knee)
c. Pivot (elbow)
d. Saddle (hand/fingers)
Freely Movable Joints and Their
Movements
Ball-and-Socket Joint
Pivot Joint
Clavicle
Humerus
Ball-andsocket
joint
Radius
Hinge Joint
Scapula
Pivot
joint
Saddle Joint
Ulna
Humerus
Femur
Patella
Fibula
Metacarpals
Tibia
Hinge
joint
Saddle joint
Carpals
Figure 36-5 Knee Joint
Muscle
Tendon
Femur
Patella
Bursa
Ligament
Synovial fluid
Cartilage
Fat
Fibula
Tibia
F. Structure of Joints
1. ligament
a. holds bones together
2. Bursa
a. small sacs of synovial fluid
b. acts as tiny shock absorbers
II. Muscular System
A. Types of Muscle Tissue
1. Skeletal
2. Smooth
3. Cardiac
Figure 36-7 Skeletal Muscle Structure
Section 36-2
B. Muscle Contraction – Sliding-Filament
Model
1. muscle contracts when the thin
filament in the muscle fiber slides over
the thick filament decreasing distance
between the Z lines
2. sarcomeres
a. myosin
1) thick filaments of protein
b. actin
1) protein making up most of
the thin filament
c. Z lines
1) separate sarcomeres
2) anchor sarcomeres
3. requires lots of ATP
a. produced by cellular respiration
b. requires Phosphorus
Cycle Diagram
1
5
Myosin
returns to
original
shape
4
Crossbridge
releases
actin
Myosin
forms
crossbridge with
actin
2
Crossbridge
changes
shape
3
Actin
pulled
C. Control of Muscle Contraction
1. CNS via motor neurons control
muscle contractions
2. difference in electrical charge across
plasma membrane
3. Neuromuscular junction
a. the point of contact between a
motor neuron and a skeletal
muscle cell
b. acetylcholine (ACo)
1) the neurotransmitter in the
vesicles of motor neurons
c. impulse causes Ca2+ ions to be
released
d. Ca affects regulatory proteins
which cause actin and myosin
to interact
e. ACo release stops
f. enzyme destroys excess ACo
g. Ca2+ pumped back in to cell
h. contraction ends
4. Phosphorus taken from ATP or from
creatine phosphate
a. ATP comes from glucose in blood
or glycogen breakdown in cells
5. strong vs. weak contraction
a. brain stimulates many or only a
few muscle cells
D. How Muscles and Bones Interact
1. Tendons
a. connect muscles and bones
b. cause bones to work like levers
2. most skeletal muscles work in
opposing pairs
3. the weight of an object’s pull and
gravity also pull on muscles
Figure 36-11 Opposing Muscle Pairs
Section 36-2
Movement
Movement
Triceps (relaxed)
Biceps
(relaxed)
Biceps
(contracted)
Triceps (relaxed)
III. Integumentary System
A. Purpose
1. serves as barrier against infection
and injury
2. helps to regulate body temp
3. removes waste from body
4. protects against UV radiation
B. Skin
Figure 36-13 The Structure of Skin
Section 36-3
B. Skin
1. epidermis
a. outer layer
b. dead cells on outside
c. inner layer – rapid cell division
d. tough, flexible, waterproof
e. melanocytes produce melanin
2. dermis
a. inner layer
b. contains collagen fibers, blood
vessels, nerve endings, glands,
sensory receptors, smooth muscles,
hair follicles
c. glands
1) sweat glands
a) cools body, rids waste
2) sebaceous glands
a) oil secretion
(waterproof)
3. under dermis is layer of fat and loose
connective tissue
End