support and locomotion chapter 36 1. skin the body’s protection 2

1

Support and Locomotion

Chapter 36

2

Skin

The body’s protection

3

Epidermis the outer layer

• Exterior layer 25-30 layers of dead, flattened cells– Constantly being shed– Keratin protective protein (elasticity)

• Interior layer living cells continually dividing– Melanin protective skin pigment

4

Epidermis cont.

• Epidermal ridges• Fingers and palms• Toes and soles• Good for gripping give increased

friction

5

Dermis the inner layer

• Blood vessels, nerves, nerve endings, hair follicles, sweat and oil glands

• Layer of fat underneath insulation and protection

6

This picture shows a false-colored SEM of human skin. 

The lower portion is the living epidermis. As those cells die, they flake off and become the stratum corneum, which does most of the work creating a barrier between the body and the outside world.

7

Functions of the skin

• Regulate body temperature• Sense organ• Vitamin D production• Physical barrier against damage and

microbial invasion

8

Aging

• Drier glands decrease production• Skin loses it’s elasticity wrinkles• Accelerated by prolonged exposure to

UV rays

9

The Skeletal System

10

Axial skeletonIncludes the skull, vertebral column, ribs, and sternum

11

Appendicular skeletonIncludes the bones of the arms and legs, and associated structures

12

Joints

Places where bones are connected

13

Ball-and-socket joint

• Allows for rotational movement

• Hips and shoulders

14

Hinge joint

• Allows for back-and-forth movement

• Elbows, knees, fingers, and toes

15

Pivot joint

• Allows bones to twist around each other

• Neck and elbows

16

Gliding joint

• Allows bones to slide past each other

• Wrists and ankles

17

Fixed joint

• Also called a fused joint

• Allows for no motion• Skull

18

Cartilage

• Bones are cushioned by a thin layer of cartilage

• Flexible, elastic tissue• Nose, ears, trachea, between each

vertebrae

19

Bursae

• Fluid-filled sacs between bones• Absorb shock

20

Arthritis

• Inflammation of the joints• Wearing down of cartilage• Bone spurs splinters• Causes infections, aging, injury,

genetic

21

Connective tissue

• Ligaments connect bone to bone– Sprain torn or stretched ligament

• Tendons connect muscles to bones– Tendonitis inflammation of the tendon

22

Bone Structure

23

Compact bone

• Very dense and strong• Outside of ends and along shafts• Osteocytes bone cells

24

• Osteon systems (Haversian canals)– Openings which allow blood vessels and

nerves through bone

25

Spongy bone

• Less dense, porous• Ends of bones

26

PeriosteumOuter covering of bone shafts

27

Osteoblasts potential bone cells

• Secrete a protein called collagen• Deposition of minerals turns them into

osteocytes ossification

28

• Osteoporosis loss of bone mass• Growth

– Length: cartilage plates at ends– Width: outer surface

• After growth repair and maintenance

29

Marrow found at the center of bones

Red marrow• Long bones only

– Production of blood cells

Yellow marrow• Most bones

– Stored fat

30

Functions of the skeletal system

• Protects internal organs• Framework for body tissues• Attachment for muscles• Production of blood cells• Mineral storage

31

Skeletal system

• Animation

32

Muscles

3 types

33

Smooth muscle

• Sheets of cells• Walls of internal organs and blood

vessels• Function squeezing (pressure)• Involuntary not under conscious

control

34

Smooth muscle tissue

35

Cardiac muscle

• Found in your heart• Interconnected bands of muscle fibers

striated• Adapted to generate and conduct

electrical impulses• Involuntary

36

Cardiac muscle tissue

37

Skeletal muscle

• Attached to bones• Controls movement• Work in opposing pairs 1 bends a limb

and the other extends the limb• Striated in appearance• Voluntary

38

Skeletal muscle tissue

39

Muscle and nerves

40

Skeletal muscle contraction

• Contraction Animation

41

Muscle strength

• The number of muscle fibers you have is fixed before birth

• Muscle fibers get bigger and more fibers contract as you increase your strength

42

Muscle fatigue when muscles hurt after use

• Due to decreased available oxygen• Cells switch from aerobic to anaerobic• Lactic acid buildup toxic, causes pain• Cure rest• Not resting can result in permanent

muscle damage

43

Comparative anatomy

44

Amoeba

• Pseudopods “false feet”• Extensions of the cell membrane that

can reach in any direction• Locomotion

45

Amoeba with pseudopods

46

Paramecium

• Have cilia to propel them through the water

• Locomotion

47

Paramecium with cilia

48

Hydra

• Pull with tentacles• Glide on base• Somersaulting• Movement

49

Hydra with tentacles

50

Earthworm

• Setae bristles used as anchors• Longitudinal muscles shorten body• Circular muscles lengthen body

51

52

Grasshopper

• Jointed appendages• Walking legs and jumping legs• 2 sets of wings• Exoskeleton made of chitin

– Attachment site for muscles

53