muscle physiology

A motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate. True\ False

false

where is the motor neuron location

traveling to the muscle

The development of tension in a muscle, in response to a single stimulus above threshold, is called a muscle ___________

twitch

With rapid, multiple stimulations, the contraction-relaxation cycles are shorter but there still is some degree of relaxation. This stage in the multiple stimuli graph is called:

incomplete tetanus

gross movements are created by _______ motor units

large

When the frequency of stimulation of a muscle is great enough, _______: a)full relaxation of the muscle occurs and wave summation results b) full relaxation of the muscle occurs c) wave summation results and muscle twitches overlap. d) muscle twitches overlap e) wave summation results

c

what are the 2 conditions that must be met for treppe to be demonstrated by a muscle stimulated multiple times

1. the sequential stimulation must not happen until the muscle has completed the relaxation phase of the the previous twitch 2. the sequential stimulation must be close enough that the muscle is still warmed up from the first stimulation

Which of the following describes the relationship between stimulus frequency and muscle tension? A) When stimulus frequency increases, muscle tension increases to a maximum value. B) When stimulus frequency decreases, muscle tension increases indefinitely. C) When stimulus frequency increases, muscle tension increases indefinitely. D) When stimulus frequency increases, muscle tension decreases.

A

Once a motor neuron has fired, all the muscle fibers in a muscle contract. True/False

false

Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer overlapped, ________. A) maximum force production would result because the muscle has a maximum range of travel B) cross bridge attachment would be optimum because of all the free binding sites on actin C) no muscle tension could be generated D) ATP consumption would increase because the sarcomere is "trying" to contract

C

The strongest muscle contractions are normally achieved by ________. A) increasing stimulus voltage above the treppe stimulus B) recruiting small and medium muscle fibers C) increasing the stimulation voltage up to the maximal stimulus D) increasing stimulus voltage above the threshold

C

What is being "added" to achieve wave summation? A) Motor units B) Muscle fibers C) Muscle twitches D) Stimulation voltage

C

What is changing to cause the variation in tension (force of contraction) seen in the graph of multiple motor unit summation ? A) The muscle stimulated B) Frequency of stimulation C) Number of motor units recruited D) Temperature of the muscle

C

What might be occurring on a molecular level during the rest periods? A)Intracellular calcium is decreasing. B)Muscle fatigue is increasing. C) Intracellular ADP and inorganic phosphate are decreasing. D) Intracellular lactic acid is increasing.

C

Which of the following is not a way muscle contractions can be graded? A) changing the frequency of stimulation B) changing the length (stretch) of the muscle. C) changing the strength of the stimulus D) changing the type of muscle fibers involved in the contraction

D

Which of the following describes how the duration of the rest period affected muscle tension (force of contraction)? A) Increasing the duration of the rest period decreased muscle tension. B) Decreasing the duration of the rest period decreased muscle tension. C) Increasing the duration of the rest period increased muscle tension. D) Decreasing the duration of the rest period increased muscle tension. E) The duration of the rest period had no affect on muscle tension.

E

Muscle tone is the small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units. True/False

True

temporal (wave) summation

What does A represent

With rapid, multiple stimulations, the contractions fuse into a smooth, continuous contraction. This stage in the multiple stimuli graph is called:

complete tetanus

phase of a muscle twitch where cross bridge cycling is taking place and sarcomeres are shortening

contraction

When a whole muscle is stimulated the force of the contraction is an all or nothing response with no variation in the amount of tension exerted. (t/f)

false

Build up of acidic compounds which affect protein functioning is happening in what part of the graph of temporal (wave) summation

fatigue

___________ is a decline in the muscle's ability to maintain a constant force of contraction after prolonged repetitive stimulation.

fatigue

phase of a muscle twitch where events of excitation-contraction coupling occur

latency

what does 10 represent

maximum contraction

Which Muscle will give the highest tension (force of contraction) when stimulated—all else being equal among the muscles? Moderately stretched Over stretched Non stretched

moderately stretched

a motor neuron and all the muscle cells it innervates is called a:

motor unit

a muscle contraction in response to a single stimulus of adequate strength is called a:

muscle twitch

the synapse between a motor neuron and the muscle cells it innervates is called

neuromuscular junction

stimulation of additional motor units will increase the strength of contraction. this process is called

recruitment

an increase in the strength of the stimulus will cause an increase in the force of the contraction caused by: (in the graph representing multiple motor unit summation)

recruitment of more motor units

phase of a muscle twitch where sarcomeres lengthen and the force generated decreases. calcium ions actively transported back to the terminal cisternae

relaxation

Which is more likely to happen in the body? - Cardiac Muscle being overstretched - Skeletal Muscle being overstretched

skeletal muscle being overstretched

precise movements are created by ______ motor units

small

where is the interneuron located

spinal cord

When a second stimulus is applied before complete relaxation, there is a greater development of tension. What is this called?

temporal (wave) summation

incomplete tetanus

what does B represent

progressive increase in force generated when a muscle is stimulated in succession

treppe

multiple motor unit summation

what does this graph represent

maximal stimulus

what does 11 represent

threshold stimulus

what does 7 represent

Why does wave summation occur? A) Muscle fibers are partially contracted when the next stimulus arrives. B) Muscle fibers have been allowed to fully relax .C) Muscle twitches are not yet overlapping. D) A large amount of time elapses between stimulations.

A

A smooth, sustained contraction is called ________. A) Single Muscle twitch B) Complete tetanus C) Multiple motor unit summation D) Temporal (wave) summation E) Treppe

B

The speed of the _______ period of a single muscle twitch depends on whether slow or fast twitch fibers are involved. A) refractory B) contraction C) relaxation D) latent

B

To transition from incomplete tetanus to complete tetanus, _______. A) the muscle fibers were allowed to relax B) stimulus frequency increased C) stimulus frequency decreased D) wave (temporal) summation was not allowed

B

What is changing to cause the variation in tension (force of contraction) seen in part B of the graph-- during incomplete tetanus of the temporal (wave) summation graph A) Stimulation voltage B) Frequency of stimulation C) Degree of muscle stretch D) Number of motor units recruited E) The muscle stimulated

B

Which of the following describes how the duration of rest periods between multiple stimulations affects the duration the maximal force can be maintained by a muscle: A) Decreasing the duration of the rest period increased the duration the maximal force can be maintained B) Decreasing the duration of the rest period decreased the duration the maximal force can be maintained C) Increasing the duration of the rest period increased the duration the maximal force can be maintained D) Increasing the duration of the rest period decreased the duration the maximal force can be maintained

C

Which of the following can trigger a muscle twitch? Pick the most complete answer a.) release of acetylcholine and electrical stimulation b.) release of acetylcholine c.)release of acetylcholine and release of calcium from the sarcolemma d.) electrical stimulation e.) release of calcium from the sarcolemma

a

Which of the following describes the relaxation phase of a muscle twitch? a.) The sarcomeres are increasing in length, and the force generated decreases. b.) The sarcomeres are decreasing in length, and the force generated increases. c.) The sarcomeres are decreasing in length, and the force generated decreases. d.) The sarcomeres are increasing in length, and the force generated increases.

a

Treppe is the phenomenon that results in _______. a.) an increase in the stimulation frequency b.) a progressive increase in the force generated with repetitive stimulation c.) motor unit recruitment d.) maximal force production by a skeletal muscle

b

When wave summation occurs, _______. a) individual muscle twitches are separated b) the muscle force generated increases c) the muscle fiber has received a single stimulus event d) the muscle force generated decreases

b

phase of a muscle twitch where sarcolemma and and T tubules depolarize

latency

the shortest phase of a muscle twitch, usually lasting less than 5 ms

latency

3 stages in order of a single muscle twitch

latency, contraction, relaxation

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the events of excitation-contraction coupling occur.

latent

what will happen to a muscle if the motor neuron is cut

the muscle becomes flaccid

the 2 variables affected the strength and degree of muscle movement are:

the number of motor units firing, and the number of muscle cells per motor unit

random, asynchronous motor unit contractions provide a low-level tension and resistance to stretch called muscle:

tone

During the initial phase of muscle contraction, each successive stimulus produces a slightly stronger contraction because of increased muscle warming and efficiency of enzymes. This stage is called

treppe

(t/f) For Treppe to be demonstrated by a muscle stimulated multiple times, the sequential stimulations must not happen until the muscle has completed the relaxation phase of the previous twitch.

true

complete tetanus

what does C represent

fatigue

what does D represent