1. Structural Support and Movement
Chapter 36 Part 1

2. Impacts, Issues Pumping Up Muscles
Increasing muscle size and strength with drugs such as “andro” has unwanted side effects and can damage other organ systems

3. 36.1 Invertebrate Skeletons
Hydrostatic skeleton
An enclosed fluid that contracting muscles act upon (as in sea anemones, earthworms)
Exoskeleton
A hardened external skeleton found in some mollusks and all arthropods
Endoskeleton
An internal skeleton, as in echinoderms

4. Hydrostatic Skeleton: Sea Anemone

5. mouth
gastro-vascular cavity; the mouth can close and trap fluid inside this cavity
Figure 36.2
Hydrostatic skeleton of a sea anemone. (a) Water is drawn into the gastrovascular cavity through the mouth. When the cavity is filled and mouth is closed, muscles can act on the trapped fluid and alter body shape. There are two sets of muscles: circular muscles ring the body; longitudinal ones run the length of the body. (b) One anemone inflated with water (left) and another that has expelled water from the gastrovascular cavity and pulled in its tentacles (right).
Fig. 36-2a, p. 618

6. Animation: Hydrostatic skeleton

7. Hydrostatic Skeleton: Earthworm

8. Exoskeleton: Fly

9. vertical muscle relaxes vertical muscle contracts
thorax
longitudinal
muscle contracts
longitudinal
muscle relaxes
vertical muscle relaxes
vertical muscle contracts
Figure 36.4
Fly wing movement. Wings attach to the thorax at pivot points. When muscles inside the thorax contract and relax, the thorax changes shape and the wings pivot up and down at their attachment point.
A Wings pivot down as the relaxation of vertical muscle and the contraction of longitudinal muscle pulls in sides of thorax.
B Wings pivot up when the contraction of vertical muscle and relaxation of longitudinal muscle flattens the thorax.
Fig. 36-4, p. 619

10. Animation: Fly wing action

11. Exoskeleton: Spider

12. 36.1 Key Concepts Invertebrate Skeletons
Contractile force exerted against a skeleton moves animal bodies
In many invertebrates a fluid-filled body cavity is a hydrostatic skeleton
Others have an exoskeleton of hard structures at the body surface
Still others have a hard internal skeleton, or endoskeleton

13. 36.2 The Vertebrate Endoskeleton
All vertebrates have an endoskeleton
Usually consists primarily of bones
Supports the body, site of muscle attachment
Protects the spinal cord
The vertebral column (backbone) is made up of individual vertebrae separated by intervertebral disks made of cartilage

14. Axial and Appendicular Skeleton
Axial skeleton
Skull
Vertebral column
Ribs
Appendicular skeleton
Pectoral girdle
Pelvic girdle
Limbs

15. Skeletal Elements: Fish and Reptile

16. vertebral column pectoral girdle pelvic girdle Figure 36.7
Skeletal elements typical of (a) a cartilaginous fish and (b) an early reptile. Compare Figures 26.12, 26.22, and
pelvic girdle
Fig. 36-7a, p. 620

17. vertebral column skull bones rib cage pelvic girdle pectoral girdle
Figure 36.7
Skeletal elements typical of (a) a cartilaginous fish and (b) an early reptile. Compare Figures 26.12, 26.22, and
Fig. 36-7b, p. 620

18. The Human Skeleton
Some features of the human skeleton are adaptations to upright posture and walking
Foramen magnum at the base of the skull allows brain and spinal cord to connect
Vertebrae stacked one above the other in an S curve

19. Bones of the Human Skeleton

20. CLAVICLE (collarbone)
A Skull bones
CRANIAL BONES
FACIAL BONES
D Pectoral girdle
and upper limb bones
CLAVICLE (collarbone)
B Rib cage
SCAPULA (shoulder blade)
STERNUM (breastbone)
HUMERUS (upper arm bone)
RIBS (twelve pairs)
RADIUS (forearm bone)
C Vertebral column,
or backbone
ULNA (forearm bone)
CARPALS (wrist bones)
VERTEBRAE 1 2 3 4 5
INTERVERTEBRAL DISKS
PHALANGES (thumb, finger bones)
METACARPALS (palm bones)
E Pelvic girdle and lower limb bones
PELVIC GIRDLE (six fused bones)
FEMUR (thighbone)
Figure 36.8
Bone (tan) and cartilage (light blue) elements of the human skeleton. Left, labels for the axial portion, and (right) for the appendicular portion.
PATELLA (kneebone)
ligament bridging
a knee joint,
side view, midsection
TIBIA (lower leg bone)
FIBULA (lower leg bone)
TARSALS (ankle bones)
METATARSALS (sole bones) PHALANGES (toe bones)
Fig. 36-8, p. 621

21. Animation: Human skeletal system

22. 36.3 Bone Structure and Function
Bones have a variety of shapes and sizes
Long bones (arms and legs)
Flat bones (skull, ribs)
Short bones (carpals)
The human skeleton has 206 bones ranging from tiny ear bones to the massive femur

23. Bone Anatomy
Bones consist of three types of living cells in a secreted extracellular matrix
Osteoblasts build bones
Osteocytes are mature osteoblasts
Osteoclasts break down bone matrix
Bone cavities contain bone marrow
Red marrow in spongy bone forms blood cells
Yellow marrow in long bones is mostly fat

24. Bone Anatomy: Long Bone

25. Figure 36.9
(a) Structure of a human femur, or thighbone, and (b) a section through its spongy and compact bone tissues.
Fig. 36-9a, p. 622

26. space occupied by living bone cell
blood vessel
nutrient canal
location of yellow marrow
Figure 36.9
(a) Structure of a human femur, or thighbone, and (b) a section through its spongy and compact bone tissues.
compact bone tissue
spongy bone
tissue
55 µm
Fig. 36-9a, p. 622

27. Figure 36.9
(a) Structure of a human femur, or thighbone, and (b) a section through its spongy and compact bone tissues.
Fig. 36-9b, p. 622

28. of dense connective tissue
spongy bone tissue
Figure 36.9
(a) Structure of a human femur, or thighbone, and (b) a section through its spongy and compact bone tissues.
compact
bone tissue
outer layer
of dense connective tissue
blood vessel
Fig. 36-9b, p. 622

29. Animation: Structure of a femur

30. Bone Functions

31. Bone Formation and Remodeling
The embryonic skeleton consists of cartilage which is modeled into bone, grows until early adulthood, and is constantly remodeled
Bones and teeth store the body’s calcium
Calcitonin slows release of calcium from bones
Parathyroid hormone releases bone calcium
Sex hormones encourage bone building
Cortisol slows bone building

32. Long Bone Formation

33. Embryo: cartilage model of bone forms Fetus:
blood vessel invades model; osteoblasts start producing bone tissue; marrow cavity forms
Newborn:
remodeling and growth continue; secondary bone-forming centers appear at knobby
ends of bone
Figure 36.10
Long bone formation, starting with osteoblast activity in a cartilage model formed earlier in the embryo. The bone-forming cells are active first in the shaft region, then at the knobby ends. In time, cartilage is left only at the ends.
Adult:
mature bone
Fig , p. 623

34. About Osteoporosis Osteoporosis (“porous bones”)
When more calcium is removed from bone than is deposited, bone become brittle and break easily
Proper diet and exercise help keep bones healthy

35. Osteoporosis

36. 36.4 Skeletal Joints—Where Bones Meet
Area of contact or near contact between bones
Three types of joints
Fibrous joints (teeth sockets): no movement
Cartilaginous joints (vertebrae): little movement
Synovial joints (knee): much movement

37. Synovial Joints
In synovial joints, bones are separated by a fluid-filled cavity, padded with cartilage, and held together by dense connective tissue (ligaments)
Different synovial joints have different movements
Ball-and-socket joints (shoulder)
Gliding joints (wrist and ankles)
Hinged joints (elbows and knees)

38. Three Types of Joints

39. Three Types of Joints

40. fibrous joint attaches tooth to jawbone
synovial joint (ball and socket) between humerus and scapula
cartilaginous joint between rib and sternum
cartilaginous joint between adjacent vertebrae
synovial joint (hinge type) between humerus and radius
Figure 36.12
(a) Examples of the three types of joints. (b) Simplified diagram of the structure of the left knee with muscles stripped away. Several ligaments attach the femur to the tibia and chunks of cartilage called menisci help keep the bones properly aligned. Compare the photo in Figure 36.8.
synovial joint (ball and socket) between pelvic girdle and femur
Fig a, p. 624

41. femur patella cartilage ligaments menisci tibia fibula Figure 36.12
(a) Examples of the three types of joints. (b) Simplified diagram of the structure of the left knee with muscles stripped away. Several ligaments attach the femur to the tibia and chunks of cartilage called menisci help keep the bones properly aligned. Compare the photo in Figure 36.8.
tibia
fibula
Fig b, p. 624

42. 36.5 Those Aching Joints
We ask a lot of our joints when we engage in sports, carry out repetitive tasks, or strap on a pair of high heels

43. Joint Injuries and Diseases
Common joint injuries
Sprained ankle; torn cruciate ligaments in knee; torn meniscus in knee; dislocations
Arthritis (chronic inflammation)
Osteoarthritis; rheumatoid arthritis; gout
Bursitis (inflammation of a bursa)

44. 36.2-36.5 Key Concepts Vertebrate Skeletons
Vertebrates have an endoskeleton of cartilage, bone, or both
Bones interact with muscles to move the body; they also protect and support organs, and store minerals
Blood cells form in some bones
A joint is a place where bones meet; there are several kinds

45. 36.6 Skeletal–Muscular Systems
Muscle fibers
Long, cylindrical cells with multiple nuclei that hold contractile filaments
Tendons attach skeletal muscle to bone
Muscle contraction transmits force to bone and makes it move
Muscles and bones interact as a lever system
Many skeletal muscles work in opposing pairs

46. Skeletal–Muscular Action

47. C The first muscle group in the upper hindlimb contracts again and draws it back toward body.
B An opposing muscle group attached to the limb forcefully contracts and pulls it back. The contractile force, applied against the rock, now propels the frog forward.
Figure 36.14
A frog on a rock demonstrating how small contractions and the action of opposing muscles can cause big movements.
A A muscle attached
to each upper hindlimb contracts and pulls it slightly forward relative
to main body axis.
Fig , p. 626

48. Opposing Muscle Groups

49. Triceps contracts, pulls the forelimb down.
Triceps relaxes.
Triceps contracts, pulls the forelimb down.
Biceps contracts at the same time, and pulls forelimb up.
At the same time, biceps relaxes.
Figure 36.15
Two opposing muscle groups in human arms.
A When the triceps relaxes and its opposing partner (biceps) contracts, the elbow joint flexes and the forearm is pulled upward.
B When the triceps contracts and the biceps relaxes, the forearm is extended downward.
Fig , p. 626

50. Animation: Opposing muscle action

51. Muscles and Tendons

52. Muscles and Tendons

53. Straightens the forearm at elbow
TRICEPS BRACHII
Straightens the forearm at elbow
BICEPS BRACHII
PECTORALIS MAJOR
Bends the forearm
at the elbow
Draws the arm forward and in toward the body
DELTOID
SERRATUS ANTERIOR
Raises the arm
Draws shoulder blade forward, helps raise arm, assists in pushes
TRAPEZIUS
Lifts the shoulder blade, braces the shoulder, draws the head back
EXTERNAL OBLIQUE
Compresses the abdomen, assists in lateral rotation of the torso
LATISSIMUS DORSI
Rotates and draws the arm backward and toward the body
RECTUS ABDOMINIS
Depresses the thoracic (chest) cavity, compresses the abdomen, bends the backbone
GLUTEUS MAXIMUS
Extends and rotates the thigh outward when walking, running, and climbing
ADDUCTOR LONGUS
Flexes, laterally rotates, and draws the thighs toward the body
BICEPS FEMORIS
Figure 36.16
(a) Muscles of the human musculoskeletal system. These are the skeletal muscles that gym enthusiasts are familiar with; many more are not shown. Also labeled is the Achilles tendon, the largest tendon in the body and the most frequently injured. It attaches muscles in the calf to the heel bone. (b) Tendons at a synovial joint. Bursae form between tendons and bones or some other structure. These fluid-filled sacs help reduce friction between adjacent tissues.
(Hamstring muscle) Draws thigh backward, bends the knee
SARTORIUS
Bends the thigh at the hip, bends lower leg at the knee, rotates the thigh in an outward direction
GASTROCNEMIUS
Bends the lower leg at the knee when walking, extends the foot when jumping
QUADRICEPS FEMORIS
Set of four muscles that flex the thigh at the hip, extend the leg at knee
Achilles tendon
TIBIALIS ANTERIOR
Flexes the foot toward
the shin
Fig a, p. 627

54. muscle tendon bursae synovial cavity Figure 36.16
(a) Muscles of the human musculoskeletal system. These are the skeletal muscles that gym enthusiasts are familiar with; many more are not shown. Also labeled is the Achilles tendon, the largest tendon in the body and the most frequently injured. It attaches muscles in the calf to the heel bone. (b) Tendons at a synovial joint. Bursae form between tendons and bones or some other structure. These fluid-filled sacs help reduce friction between adjacent tissues.
synovial cavity
Fig b, p. 627

55. Animation: Human skeletal muscles

56. 36.6 Key Concepts The Muscle–Bone Partnership
Skeletal muscles are bundles of muscle fibers that interact with bones and with one another
Some cause movements by working as pairs or groups; others oppose or reverse the action of a partner muscle
Tendons attach skeletal muscles to bones

57. Animation: Long bone formation

58. Animation: Vertebrate skeletons