2. Chapter 39 Structural Support and Movement

3. 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

4. Exoskeletons An exoskeleton is a hard encasement deposited on the surface of an animal – chitin Exoskeletons are found in most mollusks and arthropods Arthropods have a jointed exoskeleton called a cuticle, which can be both strong and flexible An arthropod must shed and regrow its exoskeleton when it grows

5. Endoskeleton An endoskeleton consists of a hard internal skeleton, buried in soft tissue – provides a rigid structure to which muscles attach – function in support, protection, and movement A mammalian skeleton has more than 200 bones Some bones are fused; others are connected at joints by ligaments that allow freedom of movement

6. ossicletube foot Echinoderm s Echinoderms have endoskeletons located within their dermis

7. Endoskeleton All vertebrates Fins or limbs attach to skeleton at pectoral and pelvic girdles pelvic girdlepectoral girdle Generalized mammal

8. Vertebrate skeletons Vertebrate Skeletons

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

10. Functions of Bone interact with muscle to enable movement support and anchor muscles enclose and protect internal organs store minerals – calcium – phosphorus produce blood cells – red bone marrow blood cells, platelets

11. Functions of Bone – yellow bone marrow mostly fat – fills cavities of adult long bones can be converted into red bone marrow – times of severe blood loss

13. Bone Growth / Renewal adjusts bone strength and helps maintain Ca levels – osteoblasts – osteoclasts compact bone – resists mechanical shock spongy bone – pockets with open spaces – often filled with red bone marrow

14. Long bone formation Bone Structure

15. Structure of a femur Bone Structure

16. 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

17. Bone Density

19. Joints areas of contact or near contact between bones 3 types – fibrous joints exist between cranial bones immovable

20. Joints – cartilaginous joints between vertebrae slightly moveable

21. Joints – synovial movable joints ligaments – connect bone to bone – osteoarthritis cartilage wears away – rheumatoid arthritis joint members become inflamed

22. Tendons Attach Muscle to Bone muscle tendon bursae synovial cavity

23. Impacts, Issues Video Pumping Up Muscles

24. Muscle contraction overview Muscle Contraction

25. Muscles 3 types – smooth – cardiac – skeletal maintains posture allows movement maintains body temperature provide joint stability contraction of muscle causes ATP breakdown

26. Structure of skeletal muscle Skeletal Muscle Structure

27. A muscle is made up of muscle cells A muscle fiber is a single muscle cell Each fiber contains many myofibrils – contain actin and myosin filaments Sacromere – functional unit of a muscle

28. Muscle Bundle of muscle fibers Nuclei Z lines Myofibril Single muscle fiber (cell) Sarcomere Plasma membrane

29. Structure of a sarcomere Sarcomere

30. Muscles components – sarcolemma cell membrane of muscle cell – sarcoplamsic reticulum stores Ca – essential for muscle contraction – myofibrils have striations formed by units called sarcomeres – myosin – actin

31. 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

32. Muscles sliding filament model – controlled by troponin and tropomyosin – actin filaments slide past mysoin – sarcomeres shorten

33. 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

35. Neuromuscular Junction Axon terminal fits into depression in sarcolemma Nerve impulse travels down axon to axon terminal ACH is released into synaptic cleft and binds with receptor sites Travels into T-tubules which cause Ca to be released from sarcoplasmic reticulum – Ca alters the configuration of actin and causes a change in binding site on actin

36. Troponin and Tropomyosin lie in groove in actin filament when muscle is relaxed, tropomyosin blocks myosin binding site myosin binding site blocked actin troponin

37. 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

38. Troponin and tropomyosin Troponin and Tropomyosin

39. Neuromuscular Junction Ach – contraction – activates release of Ca Ache – relaxation – recyles Ach – causes Ca to be reabsorbed into sarcoplasmic reticulum

41. Sliding filament model Muscle Contraction

42. 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

43. Energy Pathways creatine phosphate – storage form – gets things started – donates a phosphate to APD aerobic Respiration – primary source – produces 20 times the ATP – takes longer to produce anaerobic Respiration – produces ATP faster than aerobic – cost  build up of lactic acid

44. Energy sources for contraction ATP for Contraction

46. Pathway 1 Dephosphorylation Creatine Phosphate Pathway 2 Aerobic Respiration Pathway 3 Glycolysis Alone creatine oxygen glucose from bloodstream and from glycogen break down in cells ADP + P i relaxation contraction

48. 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

49. Types of contractions Muscle Contractions

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