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28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
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28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
28 Lecture Ppt
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28 Lecture Ppt

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  1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 28 Locomotion and Support Systems
  2. Animal Skeletons Support, Move, and Protect the Body 28-
  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. Figure 28.1A The well-developed circular and longitudinal muscles of an earthworm push against a segmented, fluid-filled coelom 28-
  5. Figure 28.1B A starfish has an endoskeleton 28-
  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. Figure 28.2 Graceful movements are possible because muscles act on bones 28-
  8. The Mammalian Skeleton Is a Series of Bones Connected at Joints 28-
  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. Figure 28.3A The human skeleton 28-
  11. Figure 28.3B Bones of the skull 28-
  12. Figure 28.3C The rib cage 28-
  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. Figure 28.4A Bones of the pectoral girdle and upper limb 28-
  15. Figure 28.4B Bones of the pelvic girdle and lower limb 28-
  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. Figure 28.5 Exercise can help prevent osteoporosis 28-
  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. Figure 28.6 Anatomy of a long bone 28-
  20. 28.7 Joints occur where bones meet 28-
  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. Figure 28.8 Arthroscopic surgery 28-
  23. Animal Movement Is Dependent on Muscle Cell Contraction 28-
  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. Figure 28.9 Selected human muscles and their functions 28-
  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. Motor unit 28-
  28. Figure 28.10A Antagonistic muscles 28-
  29. Figure 28.10B A single stimulus and a simple muscle twitch 28-
  30. Figure 28.10C Multiple stimuli with summation and tetanus 28-
  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. 28-
  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. Figure 28.12 Components of a muscle cell 28-
  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. Figure 28.13A Contraction of a sarcomere 28-
  37. Figure 28.13B Role of ATP in muscle contraction 28-
  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. Figure 28.14 Neuromuscular junction (green = ACh) 28-
  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. 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. Figure 28.16 Fast- and slow-twitch muscle fibers 28-
  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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