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Chapter 38

Chapter 38. Protection, Support, and Movement. Epithelial coverings for both vertebrates and invertebrates Protect underlying tissues May be specialized for sensory or respiratory functions. Outer epithelium secretions For vertebrates and invertebrates Lubricants or adhesives

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Chapter 38

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  1. Chapter 38 Protection, Support, and Movement

  2. Epithelial coverings for both vertebrates and invertebrates • Protect underlying tissues • May be specialized for sensory or respiratory functions

  3. Outer epithelium secretions • For vertebrates and invertebrates • Lubricants or adhesives • Odorous or poisonous substances • For many invertebrates • Protective cuticle or shell

  4. Integumentary system of vertebrates • Skin • Structures that develop from skin • Fish scales • Mammal hair • Bird feathers

  5. Mammalian skin • Hair • Claws or nails • Sweat glands • Oil glands • Sensory receptors

  6. Human skin

  7. Stratum corneum • Outer layer of the epidermis • Consists of dead cells filled with keratin for strength and to reduce water loss

  8. Stratum basale • Cells divide and are pushed upward toward the skin surface • Mature, flatten, produce keratin, and eventually die and slough off • Dermis • Dense, fibrous connective tissue

  9. Subcutaneous tissue in birds and mammals • Composed of insulating fat • The feathers of birds and the hair of mammals help maintain a constant body temperature

  10. Skeletal system • Supports and protects the body • Transmits mechanical forces generated by muscles

  11. Hydrostatic skeleton • Soft-bodied invertebrates • Cnidarians, flatworms, and annelids • Fluid in a closed body compartment • Transmits forces generated by contractile cells or muscle

  12. Hydrostatic skeleton

  13. Exoskeletons • Mollusks and arthropods • Arthropod skeleton • Composed partly of chitin • Jointed for flexibility • Nonliving skeleton does not grow • Arthropods must molt periodically

  14. Molting cicada

  15. Endoskeletons • Echinoderms and chordates • Internal skeleton that can grow • Consists of calcium-impregnated tissue • Cartilage • Bone

  16. Vertebrate axial skeleton • Skull • Vertebral column • Ribs • Sternum

  17. Vertebrate appendicular skeleton • Bones of the limbs • Pectoral girdle • Pelvic girdle

  18. Human skeletal system

  19. Long bone • Thin outer shell of compact bone • Inner spongy bone • Central cavity with bone marrow

  20. Typical long bone

  21. Endochondral bone formation • Long bones • Develop from cartilage templates • Intramembranous bone development • Develop from a noncartilage connective tissue model

  22. Cells that shape and remodel bone • Osteoblasts • Produce bone • Osteoclasts • Break down bone

  23. Vertebrate joints • Joints are junctions of two or more bones • Ligaments are connective tissue • Bands that connect bones • Limit movement at the joint

  24. Immovable joints • Sutures of the skull • Slightly movable joints • Joints between vertebrae • Freely movable joint • Enclosed by a joint capsule lined with a membrane that secretes synovial fluid

  25. Insect flight muscles • High metabolic rate required for flight • Large numbers of mitochondria • Tracheae (air tubes)

  26. Vertebrate muscle • Muscle tissue contracts • Moves body parts by pulling on them • Types of muscle • Skeletal • Smooth • Cardiac

  27. Skeletal muscle is made up of hundreds of muscle fibers • Fibers consists of threadlike myofibrils • Myofibrils composed of smaller myofilaments • Striations reflect the overlapping of muscle filaments

  28. Muscle structure

  29. Sarcomere • Contractile unit • Actin (thin) filaments • Myosin (thick) filaments

  30. Steps in muscle contraction • Acetylcholine released by a motor neuron combines with receptors on the surface of a muscle fiber • Calcium ions released from the sarcoplasmic reticulum

  31. Calcium ions bind to troponin in the actin filaments causing the troponin to change shape • Troponin pushes tropomyosin away from the active sites on the actin filaments • ATP binds to myosin

  32. ATP is split, putting the myosin head in a high-energy state • Energized myosin heads bind to the exposed active sites on the actin filaments • The actin filament is pulled toward the center of the sarcomere

  33. Myosin head binds a new ATP • Myosin head detaches from the actin • Myosin reattaches to new active sites so that the filaments are pulled past one another • Muscle continues to shorten

  34. Muscle contraction

  35. Providing energy for muscle contraction • ATP hydrolysis provides the energy to “cock” the myosin • Creatine phosphate is used for intermediate energy storage • Glycogen is the fuel stored in muscle fibers

  36. Antagonistic action of skeletal muscles • Agonist muscle contracts • Antagonist muscle relaxes • Groups of muscles work together • Series of separate stimuli timed close together produces a smooth, sustained contraction

  37. Muscle action

  38. Slow (red) fibers • Rich in mitochondria and myoglobin • Endurance activities • Fast (white) fibers • Rapid response

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