1. Protection, Support, and Movement
Chapter 37

2. Husky Adaptations
Huskies are adapted to load pulling and long distance running in cold climates
Their integument, musculature, and skeleton are specialized for this way of life

3. Integumentary System An animal’s outer covering Examples
Chitin-hardened cuticle of many invertebrates
Vertebrate skin and its derivatives

4. Vertebrate Skin Two layers Lies atop a layer of hypodermis
Upper epidermis
Lower dermis
Lies atop a layer of hypodermis
Figure 37.3 Page 646

5. Functions of Human Skin
Protects the body from injury, dehydration, UV radiation, and some pathogens
Helps control temperature
Receives some external stimuli
Produces vitamin D

6. Sunlight Damages Skin
UV light stimulates melanin production in skin; produces a tan
Tan is the body’s way of protecting itself against UV
Prolonged sun exposure causes elastin fibers to clump, skin to age prematurely

7. Langerhans Cells
White blood cells that arise in bone marrow, migrate to epidermis
Engulf pathogens and alert immune system
UV radiation can damage these cells and weaken body’s first line of defense

8. Granstein Cells Also occur in epidermis
Interact with cells that carry out immune response
Issue suppressor signals that keep immune response under control
Less vulnerable to UV damage than Langerhans cells

9. Hydrostatic Skeleton
Muscles work against an internal body fluid and redistribute it within a confined space
Radial cells are relaxed; longitudinal ones contracted
Radial cells are contracted; longitudinal ones relaxed

10. wing
Exoskeleton
pivot
point
Dorsal-ventral muscles contract, exoskeleton pops out, wings move up
Rigid, external body parts receive the applied force of muscle contraction
Dorsal-ventral muscles relax, exoskeleton pops back, wings move down
In-text figure Page 649

11. Endoskeleton All vertebrates
Fins or limbs attach to skeleton at pectoral and pelvic girdles
Generalized mammal
Figure 37.10c Page 650
pelvic girdle
pectoral girdle

12. Functions of Bone Interact with muscle to enable movement
Support and anchor muscles
Enclose and protect internal organs
Store calcium and phosphorus
Produce blood cells

13. Human Skeleton SKULL PECTORAL GIRDLES AND UPPER EXTREMITIES
cranial bones
facial bones
PECTORAL GIRDLES
AND UPPER EXTREMITIES
clavicle
scapula
humerus
radius
ulna
carpals
metacarpals
phalanges
Human Skeleton
sternum
RIB CAGE
ribs
VERTEBRAL COLUMN
vertebrae
intervertebral disks
pelvic girdle
femur
patella
tibia
fibula
tarsals
metatarsals
phalanges
PELVIC GIRDLE AND
LOWER EXTREMITIES
Stepped Art
Figure Page 651

14. Long Bone Structure Compact bone Spongy bone
Central cavity contains yellow marrow
nutrient canal
contains yellow
marrow
compact bone tissue
spongy bone
tissue
Fig (1) Page 652

15. Compact Bone Structure
Mature compact bone consists of many cylindrical Haversian systems
Haversian system
blood vessel
outer layer of
dense connective
tissue
spongy bone tissue
compact bone tissue
Fig (2) Page 652

16. Bone Marrow Yellow marrow Red marrow
Fills the cavities of adult long bones
Is largely fat
Red marrow
Occurs in spongy bone of some bones
Produces blood cells

17. Bone Remodeling
In adults, bone building and bone breakdown continue constantly
Osteoblasts deposit bone
Osteoclasts secrete enzymes that degrade it
Remodeling adjusts bone strength and helps maintain blood calcium levels

18. Bone Density Exercise can increase bone density
Osteoporosis is a decrease in bone density
May occur when the action of osteoclasts outpaces that of osteoblasts
May also occur as a result of inability to absorb calcium

19. Joints Areas of contact or near contact between bones Fibrous joints
Short connecting fibers join bones
Synovial joints
Move freely; ligaments connect bones
Cartilaginous joints
Straps of cartilage allow slight movement

20. Tendons Attach Muscle to Bone
bursae
synovial
cavity
Figure Page 654

21. Skeletal Muscle Bundles of striped muscle cells Attaches to bone
Often works in opposition
biceps
triceps
Figure Page 654

22. Major Human Muscles triceps brachii biceps brachii pectoralis major
deltoid
serratus anterior
trapezius
external oblique
latissimus dorsi
rectus abdominus
gluteus maximus
adductor longus
sartorius
biceps femoris
quadriceps femoris
gastrocnemius
tibialis anterior
Figure Page 655

23. Skeletal Muscle Structure
A muscle is made up of muscle cells
A muscle fiber is a single muscle cell
Each fiber contains many myofibrils
myofibril
Figure 37.19a Page 656

24. Sarcomere
A myofibril is made up of thick and thin filaments arranged in sarcomeres
sarcomere
sarcomere
sarcomere
sarcomere
Z line
Z line
Z line
Figure 37.19b Page 656

25. Muscle Microfilaments
Thin filaments
Like two strands of pearls twisted together
Pearls are actin
Other proteins in grooves in filament
Thick filaments
Composed of myosin
Each myosin molecule has tail and a double head
Figure 37.19c Page 656

26. Sliding-Filament Model
Myosin heads attach to actin filaments
Myosin heads tilt toward sarcomere center, pulling actin with them
Fig c-g Page 657

27. Sliding-Filament Model
Sarcomere shortens because the actin filaments are pulled inward, toward the sarcomere center
Fig a,b Page 657

28. Nervous System Controls Contraction
Signals from nervous system travel along spinal cord, down a motor neuron
Endings of motor neuron synapse on a muscle cell at a neuromuscular junction

29. Role of Calcium in Contraction
T tubules in the sarcoplasmic reticulum relay signal
Calcium ions are released

30. Troponin and Tropomyosin
Lie in groove in actin filament
When muscle is relaxed, tropomyosin blocks myosin binding site
troponin
myosin
binding site
blocked
actin
Figure Page 659

31. Troponin and Tropomyosin
When troponin binds calcium ions, it changes shape and moves tropomyosin
Cross-bridge formation and contraction can now proceed
myosin head
actin
Figure Page 659

32. Contraction Requires Energy
Muscle cells require huge amounts of ATP energy to power contraction
The cells have only a very small store of ATP
Three pathways supply ATP to power muscle contraction

33. ATP for Contraction Dephosphorylation Creatine Phosphate Aerobic
ADP + Pi
Pathway 1
Dephosphorylation
Creatine Phosphate
relaxation
contraction
creatine
Pathway 2
Aerobic
Respiration
Pathway 3
Glycolysis
Alone
glucose from bloodstream and from glycogen break down in cells
oxygen
Figure Page 659

34. Muscle Tension
Mechanical force a contracting muscle exerts on an object
For a muscle to shorten, muscle tension must exceed the load that opposes it
The load may be the weight of an object or gravity’s pull on the muscle

35. Two Types of Contraction
contracted
muscle can’t
shorten
contracted
muscle can
shorten
isotonic contraction
isometric contraction
Figure Page 660

36. Motor Unit
One neuron and all the muscle cells that form junctions with its endings
When a motor neuron is stimulated, all the muscle cells it supplies are activated to contract simultaneously
Each muscle consists of many motor units

37. Twitches and Tetanus Figure 37.25 Page 660 peak relaxation stimulus
contraction starts
time
number of stimuli per second
number of stimuli per second
tetanic
contraction
Figure Page 660
twitch
repeated stimulation

38. Muscle Fatigue An inability to maintain muscle tension
Occurs after a period of tetanic contraction
Different types of muscle show different fatigue patterns