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28 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 28 Locomotion and Support Systems
  2. 2. Animal Skeletons Support, Move, and Protect the Body 28-
  3. 3. 28.1 Animal skeletons can be hydrostatic, external, or internal <ul><li>Hydrostatic Skeleton - In animals that lack a hard skeleton, a fluid-filled gastrovascular cavity or coelom </li></ul><ul><ul><li>Offers support and resistance to contraction of muscles for mobility </li></ul></ul><ul><ul><ul><li>Example: Earthworms - When muscles contract, segments become thinner and elongate, like a squeezed balloon </li></ul></ul></ul><ul><li>Exoskeleton – Molluscs and arthropods have rigid exoskeletons </li></ul><ul><ul><li>In molluscs and arthropods it supports the animal and provides a location for muscle attachment </li></ul></ul><ul><ul><ul><li>Example: The jointed and movable exoskeleton of arthropods allows protection and flexible movements </li></ul></ul></ul><ul><li>Endoskeleton - Echinoderms and vertebrates have an internal skeleton </li></ul><ul><ul><li>Supports weight of a large animal without limiting the space for internal organs and offers protection to vital internal organs, but itself is protected by the soft tissues around it </li></ul></ul><ul><ul><ul><li>Example: The vertebrate endoskeleton is also jointed, allowing for complex movements such as swimming, jumping, flying, and running </li></ul></ul></ul>28-
  4. 4. Figure 28.1A The well-developed circular and longitudinal muscles of an earthworm push against a segmented, fluid-filled coelom 28-
  5. 5. Figure 28.1B A starfish has an endoskeleton 28-
  6. 6. 28.2 Mammals have an endoskeleton that serves many functions <ul><li>Bones protect the internal organs </li></ul><ul><ul><li>Rib cage protects heart and lungs; skull protects brain; and vertebrae protect spinal cord </li></ul></ul><ul><li>Bones provide a frame for the body </li></ul><ul><ul><li>Our shape is dependent on bones, which also support the body </li></ul></ul><ul><li>Bones assist all phases of respiration </li></ul><ul><ul><li>Rib cage lifts up and out and the diaphragm moves down, expanding the chest </li></ul></ul><ul><li>Bones store and release calcium </li></ul><ul><ul><li>Calcium ions play a major role in muscle contraction and nerve conduction </li></ul></ul><ul><li>Bones assist the lymphatic system and immunity </li></ul><ul><ul><li>Bone marrow produces white blood cells that defend the body against pathogens and cancerous cells </li></ul></ul><ul><li>Bones assist digestion </li></ul><ul><ul><li>The jaws contain sockets for the teeth, which chew food, that breaks it into pieces small enough to be swallowed and chemically digested </li></ul></ul><ul><li>The skeleton is necessary to locomotion </li></ul><ul><ul><li>Our jointed skeleton allows us to seek out and move to a suitable environment </li></ul></ul>28-
  7. 7. Figure 28.2 Graceful movements are possible because muscles act on bones 28-
  8. 8. The Mammalian Skeleton Is a Series of Bones Connected at Joints 28-
  9. 9. 28.3 The bones of the axial skeleton lie in the midline of the body <ul><li>Axial skeleton - bones in the midline of the body </li></ul><ul><ul><li>Appendicular skeleton - limb bones and their girdles </li></ul></ul><ul><li>The Skull - cranium and the facial bones form the skull, which protects the brain </li></ul><ul><ul><li>In newborns, cranial bones are joined by membranous regions called fontanels (“soft spots”) </li></ul></ul><ul><ul><li>Major bones of the cranium have the same names as the lobes of the brain </li></ul></ul><ul><ul><ul><li>At base of the skull, spinal cord passes upward through an opening called foramen magnum and becomes brain stem </li></ul></ul></ul><ul><li>The Vertebral Column - head and trunk are supported by vertebral column , which also protects the spinal cord and the roots of the spinal nerves </li></ul><ul><ul><li>Twenty-four vertebrae make up the vertebral column </li></ul></ul><ul><ul><li>Intervertebral disks , composed of fibrocartilage between the vertebrae, act as padding and prevent vertebrae from grinding against one another and absorb shock </li></ul></ul><ul><li>The Rib Cage - twelve pairs of ribs </li></ul><ul><ul><li>The rib cage protects the heart and lungs </li></ul></ul><ul><ul><li>Also swings outward and upward upon inspiration and then downward for expiration </li></ul></ul>28-
  10. 10. Figure 28.3A The human skeleton 28-
  11. 11. Figure 28.3B Bones of the skull 28-
  12. 12. Figure 28.3C The rib cage 28-
  13. 13. 28.4 The appendicular skeleton consists of bones in the girdles and limbs <ul><li>The Pectoral Girdle and Upper Limbs </li></ul><ul><ul><li>Components loosely linked together by ligaments allowing arm to move freely </li></ul></ul><ul><ul><li>Single long bone in upper arm, the humerus, has a smoothly rounded head that fits into a socket of the scapula </li></ul></ul><ul><ul><ul><li>Susceptible to dislocation </li></ul></ul></ul><ul><li>The Pelvic Girdle and Lower Limbs </li></ul><ul><ul><li>Two heavy, large coxal bones (hipbones) are joined at the pubic symphysis </li></ul></ul><ul><ul><li>Coxal bones are anchored to the sacrum, and together these bones form the pelvic cavity </li></ul></ul><ul><ul><ul><li>Weight of the body is transmitted through the pelvis to the lower limbs and then onto the ground </li></ul></ul></ul>28-
  14. 14. Figure 28.4A Bones of the pectoral girdle and upper limb 28-
  15. 15. Figure 28.4B Bones of the pelvic girdle and lower limb 28-
  16. 16. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 28.5 Avoidance of osteoporosis requires good nutrition and exercise <ul><li>While a child is growing, the rate of bone formation by bone cells called osteoblasts is greater than the rate of bone breakdown by bone cells called osteoclasts </li></ul><ul><li>Osteoporosis - bones are weakened due to a decrease in the bone mass </li></ul><ul><ul><li>Skeletal mass increases until ages 20 to 30 </li></ul></ul><ul><ul><li>Formation and breakdown of bone mass are equal </li></ul></ul><ul><ul><li>Between 40 and 50 reabsorption begins to exceed formation, and total bone mass slowly decreases </li></ul></ul><ul><li>Everyone can take measures to avoid osteoporosis </li></ul><ul><ul><li>Males and females require 1,000 mg of calcium per day until age 65 and 1,500 mg per day after age 65 </li></ul></ul><ul><ul><li>Exercise can build or maintain bone mass, but it must be weight-bearing exercise, such as dancing, walking, running, jogging, and tennis—activities that require you to be on your feet </li></ul></ul>28-
  17. 17. Figure 28.5 Exercise can help prevent osteoporosis 28-
  18. 18. 28.6 Bones are composed of living tissues <ul><li>Anatomy of a Long Bone </li></ul><ul><ul><li>Cavity usually contains yellow bone marrow, which stores fat </li></ul></ul><ul><ul><li>Thin shell of compact bone and a layer of hyaline cartilage, called articular cartilage when it occurs at joints </li></ul></ul><ul><ul><li>Compact bone makes up the shaft of a long bone </li></ul></ul><ul><ul><ul><li>Contains many osteons where osteocytes derived from osteoblasts lie in tiny chambers called lacunae </li></ul></ul></ul><ul><ul><li>Spongy bone provides strength and is filled with red bone marrow , a specialized tissue that produces blood cell </li></ul></ul>28-
  19. 19. Figure 28.6 Anatomy of a long bone 28-
  20. 20. 28.7 Joints occur where bones meet 28-
  21. 21. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 28.8 Joint disorders can be repaired <ul><li>Arthroscopic Surgery - Surgeons remove cartilage fragments, repair ligaments, or repair worn cartilage </li></ul><ul><ul><li>Small instrument bearing a tiny lens and light source is inserted into a joint, as are the surgical instruments </li></ul></ul><ul><ul><li>Arthroscopy is much less traumatic than surgically opening the joint with a long incision </li></ul></ul><ul><li>Replacing Cartilage - Tissue culture can be used so that a person’s own hyaline cartilage can regenerate in the laboratory </li></ul><ul><ul><li>Autologous chondrocyte implantation (ACI) - a piece of healthy hyaline cartilage from the patient’s knee is removed surgically </li></ul></ul><ul><ul><li>Chondrocytes, living cells of hyaline cartilage, are grown outside the body </li></ul></ul><ul><ul><li>A pocket is created over the damaged area using the patient’s own periosteum, the connective tissue that surrounds the bone </li></ul></ul><ul><ul><li>Once the cartilage cells are firmly established, the patient still faces a lengthy rehabilitation period </li></ul></ul>28-
  22. 22. Figure 28.8 Arthroscopic surgery 28-
  23. 23. Animal Movement Is Dependent on Muscle Cell Contraction 28-
  24. 24. 28.9 Vertebrate skeletal muscles have various functions <ul><li>Skeletal muscles support the body </li></ul><ul><ul><li>Skeletal muscle contraction opposes the force of gravity and allows us to remain upright </li></ul></ul><ul><li>Skeletal muscles make bones move </li></ul><ul><ul><li>Muscle contraction accounts for movements of the arms and legs the eyes, facial expressions, and breathing </li></ul></ul><ul><li>Skeletal muscles help maintain a constant body temperature </li></ul><ul><ul><li>Muscle contraction causes ATP to break down, releasing heat that is distributed about the body </li></ul></ul><ul><li>Skeletal muscle contraction assists movement in cardiovascular veins </li></ul><ul><ul><li>The pressure of skeletal muscle contraction keeps blood moving in cardiovascular veins </li></ul></ul><ul><li>Skeletal muscles help protect internal organs and stabilize joints </li></ul><ul><ul><li>Muscles pad the bones, and the muscular wall in the abdominal region protects the internal organs </li></ul></ul>28-
  25. 25. Figure 28.9 Selected human muscles and their functions 28-
  26. 26. 28.10 Skeletal muscles contract in units <ul><li>Skeletal Muscles Work in Pairs </li></ul><ul><ul><li>Skeletal muscles move the bones of the skeleton with the aid of bands of tendons that attach muscle to bone </li></ul></ul><ul><ul><li>Prime mover - The one muscle that does most of the work of moving a bone </li></ul></ul><ul><li>A Muscle Has Motor Units </li></ul><ul><ul><li>A motor unit is composed of all the muscle fibers under the control of a single motor axon and obeys an “all-or-none law”—it either contracts or does not </li></ul></ul><ul><ul><li>Simple muscle twitch - When a motor unit is stimulated by a single stimulus </li></ul></ul><ul><ul><li>Tetanus - maximal sustained contraction due to summation </li></ul></ul>28-
  27. 27. Motor unit 28-
  28. 28. Figure 28.10A Antagonistic muscles 28-
  29. 29. Figure 28.10B A single stimulus and a simple muscle twitch 28-
  30. 30. Figure 28.10C Multiple stimuli with summation and tetanus 28-
  31. 31. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 28.11 Exercise has many benefits <ul><li>Exercise programs improve muscular strength, muscular endurance, flexibility and cardiorespiratory endurance </li></ul><ul><li>Exercise also seems to help prevent certain kinds of cancer: colon, breast, cervical, uterine, and ovarian cancer </li></ul><ul><li>Physical training with weights can improve the density and strength of bones and the strength and endurance of muscles </li></ul><ul><ul><li>Helps prevent osteoporosis because it promotes the activity of osteoblasts </li></ul></ul><ul><ul><li>Helps prevent weight gain, because as a person becomes more muscular, the body is less likely to accumulate fat </li></ul></ul><ul><li>Exercise relieves depression and enhances the mood </li></ul><ul><ul><li>Makes people feel more energetic </li></ul></ul><ul><ul><li>Some people sleep better at night after exercising. Particularly if they exercise in the late afternoon. </li></ul></ul><ul><ul><li>Vigorous exercise releases endorphins, hormone-like chemicals that are known to alleviate pain and provide a feeling of tranquility </li></ul></ul>28-
  32. 32. 28-
  33. 33. 28.12 A muscle cell contains many myofibrils <ul><li>A muscle cell has a slightly different structure from other cells </li></ul><ul><ul><li>Sarcolemma - the plasma membrane </li></ul></ul><ul><ul><li>Sarcoplasmic reticulum - modified endoplasmic reticulum </li></ul></ul><ul><ul><ul><li>Serve as storage sites for calcium ions, which are essential for muscle contraction </li></ul></ul></ul><ul><ul><li>Myofibrils - long, cylindrical organelles which are the contractile portions of muscle cells </li></ul></ul><ul><ul><ul><li>Myofibril contains many contractile units called sarcomeres that lie between two visible boundaries called Z lines </li></ul></ul></ul>28-
  34. 34. Figure 28.12 Components of a muscle cell 28-
  35. 35. 28.13 Sarcomeres shorten when muscle cells contract <ul><li>Striations of skeletal muscle are due to the placement of protein filaments in sarcomeres </li></ul><ul><ul><li>Sarcomere contains thick filaments made up of myosin and thin filaments made of actin </li></ul></ul><ul><li>Sliding Filament Model </li></ul><ul><ul><li>ATP provides the energy for muscle contraction </li></ul></ul><ul><ul><li>Each myosin head has a binding site for ATP, and the heads have an enzyme that splits ATP into ADP and P </li></ul></ul><ul><ul><li>This activates the heads, making them ready to bind to actin. ADP and P remain on the myosin heads while the heads attach to actin, forming cross-bridges </li></ul></ul><ul><ul><li>Power stroke - Release of ADP and P bends crossbridge sharply </li></ul></ul><ul><ul><li>Rigor mortis occurs because ATP is needed in order for the myosin heads to detach from actin filaments </li></ul></ul>28-
  36. 36. Figure 28.13A Contraction of a sarcomere 28-
  37. 37. Figure 28.13B Role of ATP in muscle contraction 28-
  38. 38. 28.14 Axon terminals bring about muscle contraction <ul><li>Muscle cells (fibers) contract only because they are stimulated by motor axons </li></ul><ul><li>Neuromuscular junction contains a synaptic cleft where the neurotransmitter acetylcholine (ACh) is released </li></ul><ul><li>Sarcolemma of a muscle cell contains receptors for Ach molecules </li></ul><ul><ul><li>When these molecules bind to the receptors, a muscle action potential begins </li></ul></ul>28-
  39. 39. Figure 28.14 Neuromuscular junction (green = ACh) 28-
  40. 40. 28.15 Muscles have three sources of ATP for contraction <ul><li>Creatine Phosphate (CP) Pathway </li></ul><ul><ul><li>CP is a molecule that contains a high-energy phosphate and is only formed when a muscle cell is resting </li></ul></ul><ul><ul><ul><li>Simplest and most rapid way for muscle to produce ATP is to transfer the high-energy phosphate to ADP </li></ul></ul></ul><ul><li>Fermentation </li></ul><ul><ul><li>Produces two ATP from the anaerobic breakdown of glucose to lactate </li></ul></ul><ul><ul><li>Fast-acting, but it results in the buildup of lactate that causes muscle soreness </li></ul></ul><ul><ul><li>Also results in oxygen debt - oxygen required to complete metabolism of lactate and restore cells to original energy state </li></ul></ul><ul><li>Cellular Respiration </li></ul><ul><ul><li>Muscle cells have a rich supply of mitochondria where cellular respiration supplies ATP </li></ul></ul><ul><ul><ul><li>Usually from the breakdown of glucose when oxygen is available </li></ul></ul></ul>28-
  41. 41. 28.16 Some muscle cells are fast-twitch and some are slow-twitch <ul><li>Fast-Twitch Fibers </li></ul><ul><ul><li>Usually anaerobic and good for strength because their motor units contain many fibers </li></ul></ul><ul><ul><li>Provide explosions of energy and are most helpful in activities such as sprinting </li></ul></ul><ul><ul><li>Light in color because they have fewer mitochondria, little or no myoglobin, and fewer blood vessels than slow-twitch fibers </li></ul></ul><ul><ul><ul><li>Develop maximum tension more rapidly than slow-twitch fibers can, and their maximum tension is greater </li></ul></ul></ul><ul><li>Slow-Twitch Fibers </li></ul><ul><ul><li>Slow-twitch fibers have a steadier tug and more endurance, despite having more units with a smaller number of fibers </li></ul></ul><ul><ul><li>Most helpful in sports such as long-distance running </li></ul></ul><ul><ul><li>Produce energy aerobically and tire only when fuel supply is gone </li></ul></ul><ul><ul><li>Have many mitochondria and are dark because they contain myoglobin </li></ul></ul><ul><ul><li>Have a low maximum tension and are highly resistant to fatigue </li></ul></ul>28-
  42. 42. Figure 28.16 Fast- and slow-twitch muscle fibers 28-
  43. 43. Connecting the Concepts: Chapter 28 <ul><li>The skeleton is easily observable at the macro level </li></ul><ul><ul><li>We learned the names of the bones making up the axial and appendicular portions of the skeleton </li></ul></ul><ul><ul><ul><li>We considered the tissues of the bones and joints (compact bone, spongy bone, cartilage, fibrous connective tissue) </li></ul></ul></ul><ul><ul><li>We learned the names of various muscles and how they operate when we intentionally move our bones </li></ul></ul><ul><ul><ul><li>We can’t understand how skeletal muscles contract and move the bones until we study skeletal muscles at the cellular level </li></ul></ul></ul><ul><li>A muscle cell is suited to its task because it contains contractile organelles called myofibrils </li></ul><ul><ul><li>Myofibrils contain the filaments (actin and myosin) that account for muscle contraction </li></ul></ul><ul><li>Without knowing how muscles contract at the cellular level, our understanding of muscles would be incomplete </li></ul>28-

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