Skeletal Muscle Physiology: Frogs & Human Subjects (1, 2, 5-8, 10-12, 14-16)
1. There is a greatr concentration of Na+ f ; there is a greater concentration of K+ e .
When the stimulus is delivered, the ermeability of the membrane at that point is changed; and c , initiating the depolarization of the membrane. Almost as soon as the depolarization wave has begun, a repolarization wave follows it across the membrane.
This occurs as b . Repolarization restores the h of the resting cell membrane. The g is (are) reestablished by i .
2. 1
5
3
2
4
5. Electrical
Chemical
6. a) latent phase, ~3 msec, the interval from stimulus application until the muscle begins to shorten
b) contraction phase, ~27 msec, the muscle fibers shorten
c) relaxation phase, 110 msec, the muscle fibers relax & lengthen
7. 1) d
2) c
3) e
4) f
5) b
6) a
8. 1) rapid
2) lactic acid
3) more
10. The muscle become paralyzed & flaccid, & atrophy
11. As the load on a muscle increases, its strength of contraction also increases until the muscle reaches maximal force generated.
12. The way the skeletal muscles attached to skeletal system makes them slightly stretched.
By changing the length, the arrangement of myosin & actin is less optimal causing less favorable binding of Ca++
14. Due to wave summation, the muscle will contract more rapidly.
15. Producing a steady increase in muscle force by increasing the # of active motor units
16. After prolonged activity, there’s an accumulation of lactic acid & depletion of ATP, ion imbalances or tissue damage, hence the loss of the ability to contract, or muscle fatigue.

PhysioEX Skeletal Muscle Physiology (all)
Activity 1
1. Skeletal muscle fibers: cells that composes skeletal muscle
Motor unit: 1 motor neuron & all of the skeletal muscle fibers it innervates.
Skeletal muscle twitch: 1 contractile response to a single AP
Electrical stimulus: excitation of muscle contraction using electrical impulses.
Latent period: the