Physiology Lab #2 Skeletal Muscle Physiology Review – Flashcards

individual skeletal cells

consists of a motor neuron and all of the muscle fibers it innervates

the period of time that elapses between the generation of an action potential in a muscle cell and the start of a muscle contraction

the elicitation of muscle contraction using electric impulses.

the mechanical response to a single action potential

It binds to receptors and initiates a change in ion permeability that results in the contraction of the muscle cell.

This is th process of neuromuscular junction which then leads to the end-plate potential. The motor neuron then releases acetylcholine when the action potential is reached which causes a diffusion in the muscle fibers and from there binds to receptors which change ion permeabilty resulting in the contraction of the muscle cell.

*latent period- period of time that elapses between the generation of an action potential in a muscle cell and the start of muscle contraction. *contraction phase- starts at end of the latent period and ends when muscle tension peaks. *relaxtion phase- the period of time from peak tension until the end of the muscle contraction.

No, the duration of the latent period didn't really change.

Sodium ions move into the cell to bring about the membrane depolarization.

The muscle force increased as the voltage increased but once it receached the maximal voltage, the force of contraction stopped increasing and stayed the same even though you keep increasing voltage.

A steady increase in muscle force increases based on the amount of electrical current given. It still goes through threshold voltage and once the voltage goes beyond threshold, a whole muslce force occurs. Maximal voltage still takes place in vivo. tension. Whole-Muscle Force is achieved in Vivo by recruitment of additional motor units that increase the total muscle force produced.

The isolated skeletal muscle became depolarized and all fibers became involved in active force when maximal voltage was reached.

Stimulus intensity describes the amount of force generated to administer the stimulus while stimulus frequency refers to the rate of delivered stimulus to the muscle.

Stimulating the isolated skeletal muslce multiple times in a short period with complete relaxation resulted in an increase of contraction force. This result is called treppe.

The amount of total force generated by the isolated skeletal muscle inscreased when stimulus frequency increased with no relaxation of the muscle in between. This is called wave summation.

To achieve active force of 5.2g, you did not have to increase stimulus voltage above 8.5. To achieve active force of this amount, you had to increase stimulus frequency.

Wave summation releases more calcium and increases the force of contraction by increasing the firing rate of motor neurons using one muscle fiber.Recruitment use multiple motor units, in order to increase the force of contraction. There is no added calcium ions as in wave summation. Summation was achieved by firing stimuli over and over before relaxtion of the muscle causing more force recruitment was achieved by rapid firing of stimuli to get max sooner.

Increasing the stimulus frequency lead to an increase in active force generated by the whole skeletal muscle. Active force began to pleatu and maximal tetanic tension occurred.

Your answer: 50- Unfused Tetanus 140-Fused Tetanus 146+ Maximal Tetanic Tension

There was not further increase in peak force wiht stimulus frequency of 140+ Maximal Tetanic Tension

The contractile force declines because of the previous contraction.

The buildup of lactic acid, ADP, and Pi in the muscle fibers.

When the stimulator is off,there is a period of rest. This allows concentrations of Lactic acid,ADP, and Pi to decreaase. With these concentrations being at a decreased level, the length of time that the muscle is able to maintain maximum tension increases. If the stimulator was not turned off for a short time, the muscle would not be allowed to reach a rest period and further fatigue would continue.

- allow for multiple times of rest - good amount of exercise to train endurance.

The amount of total force decreased when the length of the muscle both increase and decrease passed its resting length. However, when the muscle was stretched to 100mm, it exceeded the total force than that of the resting length.

The fixed length of the skeletal muscle.

Active force data changes as the resting length of the muscle changes. The change in the active force amount is completely caused by the amount of myosis bound to actin. The shorter the muscle's resting length is, the more myosis filaments bind to actin filaments.

Muscle lengths of 80mm-100mm generated passive force.

When the bicep muscle remains at a fixed length.

When ligting the dumbell toward your shoulder.

The latent period became longer because of the decrease of muscle twitch duration and velocity. In other words, the muscle length doesn't shorten as much with the heavier loads.

When the weight is heavy, the speed in which the muscle lifts the weight decreases in speed at a slower velocity.

With an increase in weight, the shortening distance became shorter.

It takes longer to perform 10 reps lifting 10-kg than 5-kg, because with 5-kg, maximal shortening velocity is attained much faster. The heavier, the load, the slower the muscle twitch and the lighter the load, the faster the muscle twitch.

This is an isometric contraction. The muscle would generate passive force when given an electrical stimulus but with the weight pullin down on the muscle, the muscle would not visibly move. Since the weight is puling down on the muscle, the muscle is going to lengthen but not because of a contraction, but because of the weight just pulling down on it.