1. Skeletal and Muscular Systems Powerpoint #2 Unit 8 – Chapters 36 Working together to create movement

3. Skeletal System Structures : Bones Cartilage Ligaments

4. Functions Supports body Protects internal organs Allows for movement Stores mineral reserves Provides a site for blood cell formation

5. How many bones in a human Skeleton? 206 How many in babies? ~ 300 Axial Skeleton: spine, ribcage, skull Appendicular: arms, legs, pelvic girdle, shoulders What are bones? A solid network of living cells and protein fibers that are surrounded by deposits of calcium salts

6. Bones: 3 Parts Spongy bone Not soft or spongy Very strong Structure resembles the supporting structure of bridges. Strong but lightweight

7. Compact bone: Very dense (no spaces like spongy bone) Outer portion of bone Contains Haversian canal for veins and arteries to run through

8. Haversian Canals

9. Bone Marrow: Soft tissue Found in bone cavities Yellow Marrow: fat cells Red marrow: makes red blood cells, platelets and most white blood cells ~1/2 red marrow turns into yellow in adults If severe blood loss, some yellow can turn back to red

11. Development of bone: Cartilage: Tough, elastic, connective tissue Found in: ears, between bones, larynx, and other various places.

12. Development of Bone http://www.youtube.com/watch?v=78RBpWSOl08 Ossification: cartilage replaced by bone Osteoblasts:cells that build bone Osteoclasts:cells that break down bone Growth Plates (epiphyseal plates): found in most long bones (leg and arm bones) cartilage continues to grow here until completely replaced by bone during adolescence=stop growing

13. Types of Joints -Ball and socket

14. Types of Joints- Hinge

15. Types of Joints- Saddle

16. Types of Joints Pivot

17. Structure of Joints Ligaments: Connects Bone to Bone Tough, fibrous tissue

18. Anterior Cruciate Ligament

19. Fractures

20. Structure of Joints Bursa: small fluid-filled sac provides a cushion between bones and tendons and/or muscles around a joint.

21. Bursitis

22. Arthritis

23. Rheumatoid arthritis Osteoarthritis

24. Compare Osteoarthritis and normal knee

25. Total Knee Replacement

26. Total Knee Replacements

27. Total Knee Replacement

28. Osteoporosis

29. 29

32. Types of Muscle 32  The human body is comprised of ~640-850 muscles (sources varying regarding what is defined as different parts of a single muscle or as several muscles)  makes up 30-35% (in women) and 42-47% (in men) of body mass. Three types of muscle: Skeletal muscle Smooth muscle Cardiac muscle

33. A. Skeletal (Striated) Muscle  moves various parts of the skeleton  voluntary control  Repeated activation of a skeletal muscle can lead to fatigue  Can have many nuclei  Striated (striped appearance) 33

34. Skeletal Muscles work in PAIRS Bending or straightening of elbow requires the coordinated interplay of the biceps and triceps muscles 34

35. B. Smooth Muscle  Located in the blood vessels, the respiratory tract, the iris of the eye, the gastro-intestinal tract  contractions are slow and uniform  Is fatigue resistant  Activation is involuntary  Has one nucleus 35

36. C. Cardiac Muscle  Functions to provide the contractile activity of the heart  Activation is involuntary (like smooth muscle)  Can have 2 nuclei, usually has 1  Is very fatigue resistant 36

37. 37 myofibril muscle fiber muscle fiber bundle Components of skeletal muscle

38. Muscle Fibers: Cylinder-shaped cells that make up skeletal muscle 38  Made of myofibrils which is made up of a number of myofilaments  Two types of protein myofilaments: - Actin: thin filament - Myosin: thick filament  Divided into functional units called sarcomeres, seperated by region called Z lines.  Group of fibers activated via same nerve: motor unit

39. High microscope magnification of sarcomeres within a myofibril 39

42. Muscle Contraction

43. Muscle Contraction Steps 1. Myosin head attaches to binding site on actin forming a cross bridge 1. After the cross bridge is formed the myosin head bends, called a power stroke, pulling on the actin filaments and causing them to slide. 1. Myosin attached to actin until another ATP binds causing it to release (explains rigor mortis) 1. Muscle contraction is a little like climbing a rope. The cross bridge cycle is: grab -> pull -> release, repeated over and over

45. Control of Muscle Contraction (animation)animation 1. Muscle cells are "shocked” by nerve impulses from motor neurons. 2. Neurotransmitters (acetylcholine) are released by neuron, stimulating muscle fiber to release Ca 2+ 3. When a muscle is relaxed, tropomyosin blocks cross-bridges. 4. When Ca2+ high enough, it binds to troponin, displacing tropomyosin, exposing myosin binding sites on actin. 5. Myosin can now form crossbridge

46. Control of Muscle Contraction (Neuromuscular junction)

47. Tendons Connect Muscle to Bone

48. Tendon Ruptures

49. Terminology  Sprain: when a ligament is stretched too much  Strain: when a muscle or tendon is stretched too much