Chapter 1 Biology_ the Study of Life by gabyion

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									Chapter 28 Locomotion and Support Systems
Chapter Outline

I. Skeletal Remains Reveal All
        A. Bones offer clues regarding individual identity.
            1. Age differences.
                a) Teeth.
                    1) Presence/absence of baby teeth or wisdom teeth.
                b) Condition of long bones and joints between bones.
                    1) Childhood – thin, cartilaginous growth plate at ends of long bones.
                    2) Teenage – growth plate is replace by bone.
                    3) Smooth bone between hip joints – adult (older).
                    4) Damage and wear on joints and cartilage pads indicates old age.
            3. Gender differences.
                a) Pelvic bone.
                    1) Female – shallow, wider pelvis than male.
                b) Long bones.
                    1) Males – thicker, more dense, muscle attachment points are larger.
                c) Skull.
                    1) Male – square chin.
                    2) Male – eyebrow ridges are more prominent.
            4. Ethnic differences.
                a) More difficult due to mixed racial heritage.
                b) African descent.
                    1) Eyes spread further apart.
                    2) Eye sockets roughly rectangular.
                    3) Jaw large and prominent.
                c) Native American descent.
                    1) Eye sockets are round.
                    2) Cheek bones prominent.
                    3) Palate is rounded.
                d) Caucasian descent.
                    1) Palate is U-shaped.
                    2) Suture line visible.

II. Animal Skeletons Support, Move, and Protect the Body
-Critical concepts include: characteristics of hydrostatic skeletons, endoskeletons, and
exoskeletons, and functions of the mammalian endoskeleton.

   28.1 Animal skeletons can be hydrostatic, external, or internal
       A. Skeleton function.
           1. Support system.
           2. Provide rigidity, protection and muscle attachment sites.
       B Types of skeletons.
           1. Hydrostatic Skeleton.
           2. Exoskeleton.



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    3. Endoskeleton.
C. Hydrostatic Skeleton.
    1. Present in animals without a hard skeleton.
    2. Consists of fluid-filled coelom or gastrovascular cavity.
    3. Provides support and resistance to muscle contraction.
        a) Results in movement.
        b) Allows animal to change shape.
    4. Examples of animals with hydrostatic skeletons.
        a) Hydra – Facilitates contraction of body/tentacle via muscles.
        b) Planarians – Contractions facilitate movement via cilia.
        c) Roundworms – Longitudinal muscle contraction – whip-like motion.
        d) Earthworms – Segments with divided septa – contraction/relaxation
            results in elongation and swelling – movement.
    5. Also used by animals with exoskeletons or endoskeletons.
        a) Assists movement of parts via muscles.
            1) Clams – use to extend muscular foot.
            2) Seastars – use to extend tube feet.
            3) Spiders – use to move legs.
            4) Moths – use to extend tubular feeding apparatus.
            5) Elephant – use to move trunk.
D. Exoskeleton.
    1. Found in molluscs, arthropods, and vertebrates.
    2. External, rigid skeleton.
    3. Molluscs and Arthropods.
        a) Protects and supports animals.
        b) Is site of muscle attachment.
        c) Increased thickness and weight results in increased strength.
        d) Mollusc-specific characteristics.
            1) Thick, nonmobile calcium carbonate shell.
            2) Protection from environment and predators.
            3) Grows as the animal grows.
        e) Arthropod-specific characteristics.
            1) Composed of Chitin – nitrogenous polysaccharide.
            2) Protects from wear and tear, predators, and desiccation.
            3) Jointed/movable appendages – flexible movement.
            4) Does not grow with animal – molt – loss of old exoskeleton.
E. Endoskeleton.
    1. Echinoderms and vertebrates.
    2. Internal skeleton.
    3. Examples:
        a) Starfish – Plates of calcium carbonate embedded in living tissue.
        b) Vertebrates – Endoskeleton is living tissue.
            1) Sharks/rays – Composed of cartilage.
            2) Bony fishes/amphibians/reptiles/birds/mammals – bone/cartilage.
    4. Grows with the animal.
    5. Supports weight without limiting space for internal organs.



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           6. Protects vital internal organs.
           7. Is protected by soft tissues.
           8. Jointed – Allows complex movements.
               a) Swimming, running, flying, and jumping.

   28.2 Mammals have an endoskeleton that serves many functions
       A. Human endoskeleton – 20% of body weight.
       B. Comprised primarily of bone.
       C. Contains cartilage.
           1. Between vertebrae.
           2. In the nose.
           3. Part of outer ear.
           4. Part of the rib cage.
       D. Ligaments and tendons.
           1. Composed of dense connective tissue.
           2. Ligaments join bone to bone.
           3. Tendons join muscle to bone.
       E. Skeleton functions.
           1. Bones protect the internal organs.
               a) Rib cage – heart and lungs.
               b) Skull – brain.
               c) Vertebrae – spinal cord.
               d) Eye socket – eye.
           2. Bones provide a frame for the body.
               a) Leg and pelvic bones support the whole body.
               b) Shape is determined by bones.
           3. Bones assist all phases of respiration.
               a) Rib cage assists breathing.
                   1) Lifts up and out – diaphragm moves down – air enters.
               b) Produce red blood cells – transport oxygen in body.
           4. Bones store and release calcium.
               a) Released calcium has role in muscle contraction.
               b) Calcium regulates cellular metabolism/blood clotting.
               c) Storage/release based on levels in blood.
           5. Bones assist the lymphatic system and immunity.
               a) White blood cells produced from red bone marrow.
           6. Bones assist digestion.
               a) Jaws and teeth.
           7. The skeleton is necessary to locomotion.
               a) Jointed skeleton.

III. The Mammalian Skeleton Is a Series of Bones Connected at Joints
-Critical concepts include: axial skeleton, skull, vertebral column, rib cage, appendicular
skeleton, pectoral girdle, pelvic girdle, osteoporosis, tissues of bones, types of joints, and
repair of joints.




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28.3 The bones of the axial skeleton lie in the midline of the body
    A. Axial Skeleton – Bones in the midline of the body.
    B. Appendicular Skeleton – Limb bones and their girdles.
    C. The Skull.
       1. Includes cranium and facial bones.
       2. Fontanels – Membranous regions joining infant cranial bones.
           a) Join/form sutures at 2 years old.
       3. Sinuses – Air spaces lined by mucous membrane.
           a) Reduce weight of skull.
           b) Produce resonant sound to voice.
           c) Mastoid Sinuses – Drain into middle ear.
               1) Mastoiditis – Inflammation of mastoid sinuses – deafness.
       4. Names of cranial bones related to lobes of brain.
           a) Frontal Bone – Forehead.
           b) Parietal Bones – Sides of cranium.
           c) Temporal Bones – Below parietal bones, contain hole.
           d) Occipital Bone – Base/back of skull.
           e) Foramen Magnum – Opening at base of skull.
               1) Access point for spinal cord – brain stem.
       5. Facial bones.
           a) Temporal and frontal bones contribute to face.
           b) Sphenoid Bones – Flattened areas on sides of forehead – temples.
           c) Supraorbital Ridges – On frontal bone, form eyebrows.
           d) Nasal Bones – Bridge of the nose.
           e) Mandible – Lower jaw, freely movable portion of skull.
               1) Forms chin, contains tooth sockets.
           f) Maxillae – Upper jaw, portion of hard palate.
           g) Zygomatic Bones – Cheekbone prominences.
           h) Nasal Septum – Divides the nose cavity into two regions.
    D. The Vertebral Column.
       1. Protects the spinal cord and the roots of the spinal nerves.
       2. Supports the head and the trunk of the body.
       3. Serves as an anchor for other bones of body.
       4. Made of 24 vertebrae.
           a) Cervical Vertebrae – Seven bones in the neck.
           b) Thoracic Vertebrae – Twelve vertebrae in the thorax.
           c) Lumbar Vertebrae – Five bones in the small of the back.
           d) Sacral Vertebrae – Five bones fused – form single sacrum.
           e) Coccyx – Tailbone, composed of several fused vertebrae.
       5. Four curves absorb shock and assist an upright posture.
           a) Scoliosis – Abnormal lateral curvature of the spine.
           b) Kyphosis – Abnormal hunchback curvature.
           c) Lordosis – Abnormal swayback – pregnant women.
       6. Intervertebral Disks.
           a) Fibrocartilage between vertebrae – provides padding.
           b) Prevent bone grinding and absorb shock.



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           c) Allow movement of vertebrae.
           d) Deteriorate with age.
       7. The Rib Cage.
           a) Includes thoracic vertebrae, ribs, costal cartilages, and sternum.
           b) Twelve pairs of ribs.
               1) True Ribs – Upper seven pairs - attach directly to sternum.
               2) False Ribs – Lower five pairs – do not connect directly to sternum.
                   i) Three pairs connect via common cartilage.
                   ii) Two pairs are “floating” – do not attach at all.
           c) Is protective and flexible.
               1) Protects heart and lungs.
               2) Swings outward and upward upon intake of air.

28.4 The appendicular skeleton consists of bones in the girdles and limbs
    A. Appendicular Skeleton – Pectoral and pelvic girdles and attached limbs.
        1. Pectoral girdle/upper limbs – Specialized for flexibility.
        2. Pelvic girdle/lower limbs – Specialized for strength.
        3. 126 bones present.
    B. The Pectoral Girdle and Upper Limbs.
        1. Components loosely linked by ligaments.
        2. Clavicle (collarbone) – Connects sternum and scapula.
        3. Scapula (shoulder blade) – Held in place by only muscles.
            a) Allows free movement.
        4. Humerus – Single long bone of arm.
            a) Has a smooth, rounded head – fits into socket of the scapula.
            b) Socket is shallow – little support – most likely to dislocate.
        5. Ulna and Radius – Forearm bones.
            a) Meet humerus at the elbow.
            b) Bones cross when palm is next to body – allows flexibility.
        6. Hand bones.
            a) Carpal Bones – 8, similar to small pebbles.
            b) Metacarpal Bones – 5, fan out from carpel – form palm.
            c) Phalanges – Bones of fingers and thumb – long, slender, light.
    C. The Pelvic Girdle and Lower Limbs.
        1. Coxal Bones – Hipbones (two).
            a) Joined at pubic symphysis.
            b) Anchored to sacrum – form hollow cavity (pelvic cavity).
                1) Wider cavity in females accommodates childbirth.
        2. Femur – Thighbone, largest bone of the body.
        3. Tibia – Larger bone of lower leg, includes the shin (ridge).
        4. Fibula – Smaller bone of the lower leg.
        5. Ankle – Contributed by both fibula and tibia.
            a) Seven tarsal bones present.
        6. Metatarsal Bones – Form arches of foot.
            a) Longitudinal arch – Heel to toes.
            b) Transverse arch – Across the foot.



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                1) Both provide stable, springy base for body.
         7. Phalanges – Bones of the toes – stout and sturdy in the foot.

How Biology Impacts Our Lives:
 28.5 Avoidance of osteoporosis requires good nutrition and exercise
     A. Osteoblasts – Cells that contribute to bone development.
     B. Osteoclasts – Cells that contribute to bone breakdown.
     C. Bone mass continues to increase until age 20-30.
     D. Bone mass is maintained until ages 40-50.
     E. Older bones begin to reabsorb material faster than formation.
     F. Osteoporosis – Bones weaken due to decreased bone mass.
         1. Disease of aging.
         2. Men lose ~25% of bone mass.
         3. Women lose ~35% of bone mass.
         4. Decline in testosterone or estrogen is associated with disease.
         5. Symptoms are fractures in bones.
         6. Prevention.
             a) Increase calcium uptake (enhance osteoblast activity).
             b) Exposure to sunlight – for vitamin A synthesis.
             c) Bone density evaluations involve dual energy X-ray absorptiometry.
             d) Exercise increases bone mass.
             e) Medications.
                 1) Inhibit the activity of osteoclasts.
                 2) Hormone treatment enhances calcium deposition.

 28.6 Bones are composed of living tissues
     A. Medullary Cavity – Center of long bones, not solid.
         1. Contains yellow bone marrow – stores fat.
     B. Articular Cartilage – Coating of bone – allows frictionless movement.
         1. Typical of bones with joint regions.
     C. Periosteum – Fibrous connective tissue.
         1. Covers entire long bone.
         2. Absent at joint region that contains articular cartilage.
         3. Contains blood vessels, lymphatic vessels, and nerves.
     D. Compact Bone – Shaft portion of the long bone.
         1. Osteons – Regions of osteocyte production from osteoblasts.
             a) Lacuna – Specific chambers for osteocyte production.
                 1) Arranged around blood vessel canals.
                 2) Separated by matrix of collagen fibers/calcium.
     E. Spongy Bone – Present at ends of long bones.
         1. Lighter than compact bone.
         2. Provide strength to the bone.
         3. Spaces filled with red bone marrow.
             a) Produce blood cells.
     F. Growth Plate – Near end of long bone.
         1. Presence indicates growth can occur.



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         2. Disappears upon maturity.

 28.7 Joints occur where bones meet
     A. Bones join at joints.
     B. Three types of joints – different appearances.
         1. Fibrous Joints.
             a) Immovable.
             b) Ex.: Sutures between cranial bones.
         2. Cartilaginous Joints.
             a) Connected by cartilage.
             b) Slightly movable.
             c) Ex.: Ribs attached to rib cage.
         3. Synovial Joints.
             a) Freely movable.
             b) Cavity filled with synovial fluid.
             c) Synovial fluid lubricates joint.
             d) Stabilized by joint capsule – extension of periosteum.
             e) Stabilized by ligaments – fibrous bands connecting bones.
             f) Stabilized by tendons – connect muscles to bone.
             g) Bursa – Fluid-filled sacs – ease friction between bare bones.
                 1) Bursitis – Inflammation of bursa.
             h) Menisci – Crescent-shaped pieces of cartilage in these joints.
                 1) Torn cartilage – Tearing of menisci.
             i) Ball and Socket Joints.
                 1) Hips and shoulders.
                 2) Allow movement in all planes – rotational.
             j) Hinge Joints.
                 1) Elbow and knee.
                 2) Permit movement in single direction.
             k) Saddle Joints – One bone fits inside another.
             l) Gliding Joints – Bones slide against one another.
             m) Condyloid Joints – Convex surface fits inside depression of another
                 bone.

How Biology Impacts Our Lives:
 28.8 Joint disorders can be repaired
     A. Arthritis – Degeneration of articular cartilage.
        1. Worn cartilage does not grow back naturally.
        2. Exposed bone grinds – pain, swelling, restricted movement.
        3. Total joint replacement may be required.
        4. Glucosamine-chondroitin supplements.
            a) Glucosamine – promote formation and repair of cartilage.
            b) Chondroitin – Enhance water retention, inhibits enzyme degradation.
        5. Weight loss relieves arthritis.
     B. Arthroscopic Surgery.
        1. Remove fragments, repair ligaments, repair worn cartilage.



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          2. Surgical instruments inserted into joint via small hole.
          3. Joint is distended with fluid.
          4. Less traumatic than a long incision.
          5. Typically performed as an outpatient procedure.
       C. Replacing Cartilage.
          1. Tissue culture used to regenerate individual’s cartilage.
          2. Undamaged tissue is removed from patient.
          3. Chondrocytes – Grown via tissue culture.
          4. Periosteum used to form a pocket over damaged area.
          5. New tissue is inserted into the pocket.
          6. Requires rehabilitation post surgery.

IV. Animal Movement Is Dependent on Muscle Cell Contraction
-Critical concepts include: muscle functions, muscle contraction, benefits of exercise,
muscle cell anatomy, the sliding filament model of contraction, role of ATP, axon
terminal link to muscle function, sources of ATP, and a comparison between slow-twitch
and fast-twitch muscle cells.

   28.9 Vertebrate skeletal muscles have various functions
       A. Three types of muscle.
           1. Smooth Muscle – Involuntary muscle (walls of internal organs).
           2. Cardiac Muscle – Involuntary, walls of the heart.
           3. Skeletal Muscle – Voluntary movement, accounts for ~700 muscles.
               a) Approximately 40% of the weight of average human.
       B. Skeletal muscle functions.
           1. Skeletal Muscles Support the Body.
               a) Contraction opposes the force of gravity – remain upright.
           2. Skeletal Muscles Make Bones Move.
               a) Movements of arms and legs.
               b) Movements of eyes, facial expressions, and breathing.

   28.10 Skeletal muscles contract in units
       A. Skeletal Muscles Work in Pairs.
           1. Tendons attach muscles to bone.
           2. Prime Mover – Muscle that does most of work moving bone.
               a) Contraction shortens the muscle – pulls on tendon and bone – moves.
               b) Only pull bones, cannot push.
               c) Work in antagonistic pairs.
               d) If simultaneous contraction of pair – no movement.
       B. A Muscle Has Motor Units.
           1. Allow for degrees of contraction.
           2. Motor Unit – All muscle fibers under the control of a single motor axon.
           3. Muscle is divided into multiple motor units.
           4. Motor units obey an all or nothing law – either contracts or does not.
           5. Variation in number of muscle fibers per motor unit.
               a) Less fibers per motor unit indicates more fine control.



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         6. Simple Muscle Twitch – Motor unit stimulation by single stimuli.
              a) Latent Period – Time between stimulation and initiation of
                  contraction.
              b) Contraction Period – Muscle shortens.
              c) Relaxation Period – Muscle returns to former length.
         7. If multiple stimuli.
              a) Summation – Increased muscle contraction up to maximal level.
              b) Tetanus – Maximal contraction.
              c) Fatigue – Depletion of energy reserves – relaxes in presence of stimuli.
         8. Recruitment – Sequential activation of motor units in response to stimulus.

How Biology Impacts Our Lives:
 28.11 Exercise has many benefits
     A. Improve muscular strength, endurance, and flexibility.
     B. Improve cardiorespiratory endurance.
         1. Enhanced heart rate/capacity.
         2. Enhanced lung capacity.
     C. Improves body composition – proportion of protein to fat.
     D. Linked to enhanced cancer prevention.
     E. Improve density and strength of bones and muscles.
         1. Inhibits osteoporosis.
     F. Enhances metabolism – burns fat more efficiently.
     G. Relieves depression.
     H. Improved self-esteem.

 28.12 A muscle cell contains many myofibrils
     A. Muscle cells have different structure than other cells.
        1. Sarcolemma – Plasma membrane.
            a) Forms transverse (T) system.
                1) T tubules penetrate into cell – contact ER but do not fuse with it.
        2. Sarcoplasmic Reticulum – Modified ER.
            a) Expanded regions are sites of calcium ion storage.
                1) Important for muscle contraction.
        3. Myofibrils – Long, cylindrical organelles.
            a) Contractile portions of muscle cells.
                1) Sarcomeres – Contractile units in myofibril.
                    i) Found between Z-line boundaries.

 28.13 Sarcomeres shorten when muscle cells contract
     A. Skeletal muscle striations due to protein filament placement.
     B. Sarcomere organization.
         1. Thick filaments consist of myosin.
             a) Bundles of myosin molecules.
             b) Molecules have many globular heads.
         2. Thin filaments of actin.
             a) Actin filaments – Long strands of globular actin molecules.



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           b) Twisted together.
           c) Attached to Z lines.
       3. H zone – Contains only myosin filaments (no globular heads).
   C. Appearance of sarcomere.
       1. Contracted.
           a) Actin filaments are close to center.
           b) H zone nearly disappears.
           c) Actin filaments slide past myosin filaments.
   D. Sliding Filament Model.
       1. Many myosin heads act in unison for contraction.
       2. Contraction occurs in cycles.
       3. Each cycle brings actin filaments closer to the center of sarcomere.
       4. ATP provides energy.
       5. Process:
           a) ATP binds to myosin head.
           b) ATP breaks down to ADP + P which remain on head.
           c) Myosin head binds to actin.
           d) ADP + P come off and the head pulls actin filament toward center of
               sarcomere.
           e) Release of ADP and P is associated with a power stroke.
   E. Rigor Mortis – Stiffening of muscles after death.
       1. Used to estimate time of death.
       2. Begins within three hours at 21-24C.
           a) Max rigidity achieved after 10-12 hours.
       3. Stiffness persists for 24-36 hours then muscles begin to relax.
       4. Occurs due to inability to detach myosin heads – no ATP.

28.14 Axon terminals bring about muscle contraction
    A. Motor axons stimulate muscle cells to contract.
    B. Motor axon branches terminate very close to muscle cells.
    C. Neuromuscular Junction – Region of association.
       1. Region contains a synaptic cleft.
       2. Axon terminals release acetylcholine.
       3. Sarcolemma contains acetylcholine receptors.
       4. Initiates a muscle action potential.
       5. Action potential movement down T tubules releases calcium.
       6. Calcium binds actin filaments exposing myosin binding sites.
       7. ATP presence initiates contraction.

28.15 Muscles have three sources of ATP for contraction
    A. Muscle cells can store limited amount of ATP.
    B. Three methods of ATP acquisition when store runs out.
        1. Creatine Phosphate (CP) Pathway.
            a) Creatine phosphate – Contains high energy phosphate.
            b) Formed only when muscle cell is resting.
            c) Very little is stored.



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               d) High energy phosphate is transferred to ADP.
               e) Reaction occurs during filament sliding.
               f) Is the most rapid method for ATP access.
               g) Used at the beginning of exercise – short term, high intensity.
           2. Fermentation.
               a) Produces two ATP from anaerobic breakdown of glucose.
               b) Forms Lactate.
               c) Fast-acting.
               d) Results in short-term muscle fatigue/soreness – due to lactate.
               e) Results in oxygen debt – uses oxygen to restore cells.
           3. Cellular Respiration.
               a) Mitochondria in high numbers.
               b) Breakdown of glucose using oxygen produces ATP.

   28.16 Some muscles cells are fast-twitch and some are slow-twitch
       A. Muscle cells can be classified based on preference for ATP pathway.
       B. Fast-Twitch Muscles.
           1. Rely on creatine phosphate pathway and fermentation.
           2. Anaerobic.
           3. Designed for strength – motor units contain many fibers.
           4. Lighter color – fewer mitochondria/lower myoglobin/fewer vessels.
           5. Develop maximum tension more rapidly – also greater tension.
           6. Accumulate lactate due to dependence on anaerobic methods.
           7. Fatigue quickly.
       C. Slow-Twitch Muscles.
           1. Rely on cellular respiration – aerobic.
           2. More endurance.
           3. Have more units with less fibers in each.
           4. Tire only when fuel supply is gone.
           5. Many mitochondria/myoglobin/vessels – dark in color.
           6. Low maximum tension – but highly resistant to fatigue.

V. Connecting The Concepts
      A. Skeletal movement is based on skeletal muscle.
      B. Skeletal muscle contraction occurs at the cellular level.
      C. Bones and muscles have functions suited to structure.
      D. The components of each bone or tissue allow function.
      E. Investigation at micro and macro levels allows complete understanding.
      F. Special bones, tissues, joints, and cells make up the functional system.




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