1. Ch. 39- Locomotion & Support Systems

2. 3/20/20162 I. Locomotion A. Active travel from place to place B. Depends on the ability to overcome two forces: 1. Friction 2. Gravity C. These factors vary depending upon the environment

3. 3/20/20163 D. Swimming 1. Gravity not much of problem a. Water supports weight 2. Friction is a problem a. Water is dense; much resistance 3. Modes of swimming: a. Insects - use legs as oars b. Squid - jet propelled c. Fish - move bodies side to side d. Marine mammals - move body up and down 4. Streamlined shape is important

4. 3/20/20164 E. Locomotion on Land 1. Little friction problem a. Air offers little resistance 2. Gravity is a problem a. Animal must support itself b. Leg muscles expend energy:  to propel forward  to keep from falling down c. Powerful muscles & strong skeleton are important

5. 3/20/20165 3. Types of Land Locomotion a. Hopping - kangaroos  Powerful leg muscles generate power & then store energy when animal lands b. Walking - dogs, etc.  4-legged creature keep 3 legs on ground at one time  2-legged ones have 1 leg on ground at any time (less stable) c. Running - all feet off ground at times

6. Horse Running

7. 3/20/20167 d. Crawling  Friction is a problem  Snakes: Crawl rapidly by undulating body Move slowly using movable scales on underside  Earthworms Use peristalsis:  Circular & longitudinal muscles alternate contractions & move worm forward

8. Locomotion in an Earthworm

9. 3/20/20169 4. Flying a. Gravity is a problem b. Key is shape of wings. All wings must be airfoils. These are structures whose shape alters air currents in a way that creates lift c. Air pressure under wing is greater & this lifts the wing

10. 3/20/201610 II. Skeletal Support A. Functions of skeletons: 1. Help in movement 2. Support animal against gravity 3. Protect soft parts B. Types of skeletons: 1. Hydrostatic 2. Exoskeletons 3. Endoskeletons

11. 3/20/201611 C. Hydrostatic skeleton 1. Fluid held under pressure in a closed body compartment a. Gives body shape b. Helps protect parts c. Provides support for motion 2. Fluid inside coelom of earthworm acts as a hydrostatic skeleton: a. Muscles work against it 3. Works well for aquatic organisms & those that crawl or burrow

12. 3/20/201612 D. Exoskeleton 1. Rigid external skeleton a. Mollusks - calcium carbonate b. Arthropods - chitin 2. Muscles attach to inner surfaces of exoskeleton to help move jointed body parts 3. Provides protection, support & flexibility 4. Must be molted & replaced by large exoskeleton when animal grows

13. mmm Exoskeletons

14. mmm Molting an Exoskeleton Disadvantage: Must molt to grow. At this time they are very vulnerable to predators.

15. 3/20/201615 E. Endoskeleton 1. Hard or leathery supporting elements situated among soft tissues of animal a. Sponges - hard spicules b. Echinoderms - hard plates c. Vertebrates - cartilage or bone  Sharks - ALL cartilage  Other vertebrates retain cartilage in areas where flexibility is needed (joints)

16. Shark Endoskeleton

17. Vertebrate Endoskeleton Know these advantages

18. 3/20/201618 III. Human Skeleton A. Skeleton is upright. Has 2 main parts: 1. Axial skeleton  Skull, vertebral column, sternum, thoracic cage (ribs) 2. Appendicular skeleton  Limbs (fore- & hind-)  Girdles (pelvic & pectoral) B. Skull balanced atop backbone C. Backbone is S-shaped D. Hands for grasping E. Feet for walking on 2 legs

19. The Human Skeleton

20. 3/20/201620 F. Bones 1. Bones are living, moist tissue 2. Consist of: a. Connective tissue on outside b. Cartilage at ends forms cushion for joints c. Matrix  Material secreted by the living cells.  Consists of fibers of collagen in calcium salts

21. Anatomy of Long Bones

22. 3/20/201622 3. Structure of Long Bones a. Shaft composed of compact bone  Dense matrix b. Central cavity contains:  Yellow bone marrow (stores fat) c. Ends composed of:  Compact bone on outer layer  Spongy bone in inner layer  Little cavities with red bone marrow (produces blood cells)

23. Anatomy of Long Bones

24. 3/20/201624 G. Axial Skeleton 1. Skull: a. Protects brain b. Formed of cranium & facial bones Membranous regions, called fontanels, join cranial bones in newborns Become sutures by age 2 c. Opening at base of skull for spinal cord is called the foramen magnum d. Mandible = lower jaw e. Maxilla = upper jaw

25. Human Skull

26. 3/20/201626 2. Vertebral Column a. Supports head & trunk b. Protects spinal cord & roots of spinal nerves c. There are 24 vertebrae: 7 cervical (neck) 12 thoracic (chest) 5 lumbar (small of back) 5 sacral (fused into sacrum) coccyx (tailbone) d. Intervertebral disks, composed of fibrocartilage between vertebrae, act as padding.

27. 3/20/201627 3. Rib Cage a. Contains thoracic vertebrae, ribs, costal cartilages & sternum (breastbone) b. Ribs: 12 pairs Top 7 pairs are “true ribs” because they attach to sternum Lower 5 are “false ribs” c. Protects heart & lungs d. Moves up & down during breathing

28. The Rib Cage

29. 3/20/201629 H. Appendicular Skeleton 1. Pectoral girdle & arms a. Linked loosely by ligaments b. Scapula (shoulder blades) held in place only by muscles c. Humerus fits into socket of scapula ●Very flexible; little stability 2. Pelvic girdle & legs a. Coxal bones (hips) anchored to sacrum b. Pelvic cavity wider in females

30. Pectoral Girdle & arm Pelvic Girdle & leg

31. Pelvic Girdles of Male & Females

32. 3/20/201632 I. Types of Joints 1. Bones are connected at joints 2. Three types of joints: a. Fibrous Immovable. Ex. = sutures b. Cartilaginous Slightly movable. Ex. = vertebrae c. Synovial joints Freely movable. Bones are separated by a cavity. Ligaments bind two bones to each other

33. 3/20/201633 3. Types of Synovial Joints a. Ball-and-socket joint ♦ Allow rotation in several planes ♦ Humerus in pectoral girdle & femur in pelvic girdle b. Hinge joint ♦ Allows movement in single plane ♦ Knee & elbow c. Pivot joint ♦ Allows one rotation ♦ Wrist; neck vertebrae joint

34. Knee Joint

35. Human Musculature

36. 3/20/201636 III. Bone-Muscle Movements A. Muscles connect to bones via tendons B. Muscles can ONLY contract 1. Contraction active process 2. Relaxation passive process C. Antagonistic pairs 1. Muscles that attach to same bone & move it in opposite directions a. biceps & triceps

37. Antagonistic Pairs of Muscles

38. 3/20/201638 IV. Types of Muscles A. Skeletal muscle 1. Striated in appearance a. Have light & dark bands 2. Cells cylindrical & contain many nuclei 3. Produces movement of body a. Limbs, trunk, face, eyes 4. Innervated by somatic nervous system a. under conscious control

39. Types of Muscle Tissue

40. 3/20/201640 B. Cardiac Muscle 1. Found in heart 2. Striated fibers; single nucleus 3. Innervated by autonomic N.S. a. Not consciously controlled C. Smooth Muscle 1. Found in walls of digestive tract; blood vessels 2. Long, thin cells; single nucleus 3. Cells form sheets of muscle 4. Innervated by autonomic N.S.

41. Types of Muscle Tissue

42. 3/20/201642 V. Muscle Contraction A. Macroscopic Functioning 1. Simple Twitch a. If you give one brief above-threshold stimulus to a muscle it will respond with one swift twitch 2. Summation a. If the stimuli are given before complete relaxation has occurred, a greater contraction will occur. 3. Tetanus a. If a rapid series of stimuli are given the muscle will not relax between contractions & you will get one smooth sustained contraction

43. Muscle Contraction A = simple twitch, B = summation, C = tetanus

44. 3/20/201644 B. Microscopic Anatomy & Physiology 1. Whole muscles are composed of individual muscle fibers. Each fiber is a cell. a. Sarcolemma – plasma membrane ●Forms a T-tubule system. This penetrates down into the cell & comes into close contact with specialized ER called the sarcoplasmic reticulum ♦Serve as storage site for Ca 2+ ions b. Sarcoplasmic reticulum encases hundreds of myofibrils, the contractile portions of the muscle fiber

45. Skeletal Muscle Structure

46. Skeletal Muscle Fiber

47. 3/20/201647 2. Sarcomere structure a. Myofibrils are cylindrical. b. They are striated (banded) ♦Striations due to placement of protein filaments within contractile units called sarcomeres. c. Sarcomere structure: ♦Extends between 2 dark Z lines. ♦Thick filaments, myosin. ♦Thin filaments, actin. ♦I band – lightest region (only actin) ♦H zone – medium (only myosin) ♦A band – darkest region (both a & m)

48. Sarcomere Structure

49. 3/20/201649 3. Sliding Filament Model a. As muscle fiber contracts, the sarcomeres within the myofibrils shorten b. The actin filaments slide past the myosin filaments. ♦The I band shortens ♦The H zone nearly disappears c. The filaments do NOT change length d. This movement is called the sliding filament model of muscle contraction

50. Sarcomere Functioning

51. 3/20/201651 4. Details of Sarcomere Structure a. Molecules involved: ♦Creatine phosphate ♣ High energy compound found in muscles. ♣ It passes a phosphate group to ADP to form ATP in muscles Creatine-P + ADP ATP + creatine

52. ♦Myosin filaments Bundles of myosin molecules with double globular heads (cross-bridges)

53. ♦Actin filaments 1. Double row of twisted actin molecules 2. Threads of tropomyosin wind about actin filaments 3. Troponin occurs at intervals along the threads

54. 3/20/201654 5. Neuromuscular Junction a. Muscles stimulated by motor nerves. b. Gap between neuron & muscle cell is called the neuromuscular junction. c. Motor neuron releases the transmitter acetylcholine (ACh) d. ACh binds to receptors in sarcolemma of muscle fiber e. This generates impulses that spread down the T tubules to the sarcoplasmic reticulum (SR) f. The SR then releases calcium ions g. This causes the contraction of the myofibril units

55. Neuromuscular Junction

56. Sliding Filaments – Actin & Myosin

57. 3/20/201657 6. How does Ca 2+ cause contraction? a. The released Ca 2+ ions combine with the troponin. b. This causes a conformational change which causes the tropomyosin threads to shift their position c. This in turn exposes myosin binding sites on the actin molecules d. Myosin heads, which function as ATPase enzymes, split ATP into ADP + P. e. This activates the heads so they can bind to actin

58. Sliding Filaments in Action

59. 3/20/201659 f. The ADP + P remain on myosin heads until the heads attach to the actin, forming cross bridges. g. Then ADP + P are released which causes cross-bridges to change their positions. This is called the power stroke. h. When more ATP molecules bind to myosin heads, the cross-bridges are broken as the heads detach from the actin. i. Contraction continues until nerve impulse ends and all calcium is returned to storage sites.