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CASE STUDY: Skinny 22 yr old male suffers from severe cramping, increased…

- - - - local depolarization triggers an action potential in sarcolemma
    - - b) calcium ions are released
      - c) calcium binds to troponin and removes tropomyosin out of the way
      - a) action potential moves along sarcolemma
      - d) contraction begins
    - - c). ACh binds to sarcolemma
      - ACh causes local depolarization
      - b) ACh released into synaptic cleft
      - a) motor neuron fires an action potential down its axon
    - - b) power stroke
        
        ADP & P are released and the myosin head pivots & bends
        
        pulls actin filament toward M line
      - c) cross bridge detachment
        
        after ATP attaches to myosin the link weakens, myosin head detaches
      - a) cross bridge formation
        
        myosin head attaches to actin
      - d) cocking of myosin head
        
        myosin hydrolizes ATP to ADP and P, the myosin head returns to its prestroked high energy position
    - - Isometric (increasing muscle tension)
        
        does not shorten or lengthen
        
        load is greater than force
        
        lifting something too heavy
        
        upright posture
        
        holds joints
        
        cross bridge generate force but do not move thin filaments
      - Isotonic (muscles change in length)
        
        eccentric
        
        muscle generates force as it lengthens
        
        anterior thigh muscles (walking down a steep hill)
        
        more forceful contractions
        
        muscle stretching causes microtrauma which results in soreness
        
        concentric (more familiar)
        
        muscle shortens & does work
        
        kicking a ball
        
        picking up a book
    - - anaerobic pathway
        
        oxygen use
        
        none
        
        products
        
        2 ATP per glucose
        
        energy source
        
        glucose
        
        duration
        
        30-40 seconds
        
        glycolysis & lactic acid formation
      - aerobic pathway
        
        oxygen use
        
        required
        
        products
        
        32 ATP per glucose, water, carbon
        
        energy source
        
        glucose
        
        free fatty acids from adipose tissue
        
        pyruvic acid
        
        amino acids from protein catabolism
        
        duration
        
        hours
        
        aerobic respiration
      - direct phosphorylation
        
        oxygen use
        
        none
        
        products
        
        1 ATP per CP
        
        energy source
        
        creatine phosphate
        
        duration
        
        15 seconds
        
        creatine phosphate & ADP
  - - - contractability
        
        ability to shorten forcibly
      - extensibility
        
        ability to extend or stretch
      - excitability
        
        "responsiveness" ability to respond to stimuli
      - elasticity
        
        ability of a muscle to recoil after stretching
    - - cardiac
        
        only occurs in heart
        
        striated
        
        involuntary
      - skeletal
        
        striated
        
        voluntary
        
        longest muscle cells
      - smooth
        
        helps body fluids pass through
        
        non striated
        
        found in walls of hollow visceral organs(stomach, urinary bladder & respiratory passages)
        
        involuntary
    - - TISSUE
        
        fascicle (portion of muscle)
        
        bundle of muscle cells called muscle fibers surrounded by PERIMYSIUM (irregular connective tissue)
      - CELL
        
        muscle fiber
        
        surrounded by endomysium (fine areolar connective tissue)
        
        each muscle fiber is surrounded by SARCOLEMMA (plasma membrane)
      - ORGAN
        
        muscle
        
        covered externally by EPIMYSIUM (dense irregular connective tissue)
      - ORGANELLE
        
        myofibril
        
        made up of bundles of myofilaments; 1 segment is called a sarcomere
      - MOLECULAR
        
        sarcomere
        
        contractile unit made up of myofilaments
        
        myosin (thick)
        
        actin (thin)
        
        subunits help actin
        
        tropomyosin
        
        1 more item...
        
        troponin
        
        1 more item...
        
        Z disk to Z disk
        
        Striations
        
        Dark A band
        
        H zone (thick filaments) gap between the ends of actin
        
        M line anchors myosin (dark line formed by myomesin)
        
        Light I band (thin filaments only)
        
        Z disc (holds actin in place)
    - - Maintain posture and body position
        
        skeletal muscle continuously maintains posture at all times
      - Stabilize joints
        
        as they pull on bones, muscles strength and stabilize joints of the skeleton
      - Produce Movement
        
        blood circulates with the help of cardiac muscle in the heart
        
        skeletal muscles are responsible for locomotion
        
        smooth muscle in digestive, urinary & reproductive tract help move bodily fluids/foodstuffs
      - Generate heat
        
        generate heat as they contract
  - - - more motor units = greater force
    - - more area for tension to occur
    - - contractions are summed (temporal summation & tetny)
    - - length-tension relationship; 80%-120% = optimal stretch
  - - - decreased ATP & magnesium
      - increased inorganic phosphate
      - decreased glycogen
      - ionic imbalance
        
        reduces size of action potential
        
        disrupts membrane potential
    - - the need to replenish oxygen reserves
      - accumulated lactic acid must be converted into pyruvic acid
      - glycogen must be replaced
      - ATP & creatine phosphate reserves must be resynthesized
  - - - rich capillary supply; red to pink fibers
      - recruited 2nd
      - depends on oxygen & aerobic pathway w/ SOME anaerobic gylcolysis
      - large fibers
      - fast contraction & myosin ATP activity
      - many mitochondria
      - sprinting; walking activites
    - - anaerobic glycolysis
      - low myoglobin; white pale fibers
      - fast contraction; fast myosin ATP
      - low mitochondria
      - powerful movements; hitting baseball
      - recruited 3rd
      - fatigable
      - medium sized fibers
    - - slow contractions & myosin ATP activity
      - depends on oxygen & aerobic pathway
      - resists fatigue; has high endurance
      - little power; small size
      - rich capillary supply; red fibers
      - many mitochondria
      - endurance type of activities
      - recruited 1st
- - - - exercising too frequently
      - too much cardio
      - ion imbalance
      - regiment is too intense
    - - pros
        
        lowers cholesterol
        
        lowers blood pressure
        
        promotes weight loss
        
        increases antioxidant intake
      - cons
        
        limited food choices
        
        lacks vital nutrients; b12, omega-3 fatty acids etc
        
        not optimal for gaining muscle mass
        
        dislikes soy
- - - - can cause
        
        increased risk of type 2 diabetes
        
        weight gain
        
        high blood pressure
    - - not allowing muscles to heal