Lab 7 HW

Select the two types of myofilaments found in muscle cells that cause muscle contraction.

Actin & Myosin

What phase immediately follows the stimulus in a muscle twitch?

Lag phase

The increase in muscle temperature during an athlete's "warm up," will __________.

Increase the rate enzymatic reactions, causing the muscle to respond faster and with more force

A muscle spasm is the _________ recruitment of numerous muscle fibers.

Spontaneous

In order to contract, a skeletal muscle must be stimulated by a/an __________.

Nerve

What happens to the strength of contraction during wave summation?

It increases

How does the muscle respond to weight when it is first contracting versus when it is fatigued?

Muscle contractions are smoother when first contracting. When the muscle is fatigued, the contraction becomes more spasmodic.

What do you call the continuous smooth contraction of muscle brought about by rapid, sequential stimuli?

Tetanus

The lowest voltage stimulus at which all muscle fibers are stimulated is called the _________.

Maximum recruitment

To cause muscle contraction, calcium must be released from the __________.

Sarcoplasmic reticulum

What chemical crosses the synapse, causing a muscle to contract?

Acetylcholine (ACh)

Does a single muscle fiber or an entire muscle contract by an all-or-none response?

A single muscle fiber

Define subthreshold stimulus.

A stimulus that is too weak to elicit a response or contraction in the muscle because it does not reach the required threshold value.

How do tetanus and twitch, as demonstrated in the lab, correlate to human muscle contraction? Which one is more reflective of human muscle response? Why?

A twitch represents a single, isolated contraction and relaxation cycle, whereas tetanus represents a sustained, smooth contraction caused by rapid, sequential stimuli.

Tetanus is more reflective of normal human muscle response because the nervous system sends continuous trains of action potentials to produce smooth, sustained movements.

In the following illustration, which one is the contraction phase, the lag period, and the relaxation phase?

(A) The lag period is the initial flat phase immediately following the stimulus

(B) The contraction phase is the upward-sloping phase where tension increases

(C) The relaxation phase is the downward-sloping phase where tension decreases.