Question 1

Which of the following best describes the sequence of events at the neuromuscular junction leading to muscle fiber contraction?

Accepted Answer

Acetylcholine is released from the motor neuron, binds to receptors on the muscle fiber, causing sodium ions to enter and depolarize the membrane.

Question 2

During excitation-contraction coupling, which event directly triggers the release of calcium ions from the sarcoplasmic reticulum?

Accepted Answer

Depolarization of the T-tubule membrane.

Question 3

Which of the following correctly lists the steps of the cross bridge cycle in order?

Accepted Answer

Cross bridge formation, power stroke, cross bridge detachment, cocking of myosin head.

Question 4

A motor unit consists of:

Accepted Answer

A single motor neuron and all the muscle fibers it innervates.

Question 5

Which phase of a muscle twitch is characterized by the time between stimulus application and the beginning of contraction?

Accepted Answer

Latent period

Question 6

Smooth, graded contractions of a skeletal muscle are primarily produced by:

Accepted Answer

Recruitment of additional motor units and increased frequency of stimulation.

Question 7

Which of the following best differentiates isometric from isotonic contractions?

Accepted Answer

Isometric contractions generate tension without changing muscle length, while isotonic contractions change muscle length.

Question 8

Which factor would most likely increase the force of skeletal muscle contraction?

Accepted Answer

Increasing the number of active motor units.

Question 9

A patient is unable to produce rapid, powerful muscle contractions. Which type of skeletal muscle fiber is most likely deficient?

Accepted Answer

Fast glycolytic fibers

Question 10

Which equation best represents the relationship between force ($$F$$), velocity ($$v$$), and duration ($$t) of a $$skeletal muscle contraction?

Accepted Answer

$$F = m 	imes a$$

Question 11

During the relaxation phase of a muscle twitch, which event occurs?

Accepted Answer

Calcium ions are actively transported back into the sarcoplasmic reticulum.

Question 12

Which of the following scenarios best illustrates the concept of recruitment in skeletal muscle contraction?

Accepted Answer

Lifting a heavier object by activating more motor units.

Question 13

Which type of skeletal muscle fiber is most resistant to fatigue and why?

Accepted Answer

Slow oxidative fibers, because they have high mitochondrial content and use aerobic metabolism.

Question 14

A muscle twitch consists of which three phases?

Accepted Answer

Latent period, contraction period, relaxation period.

Question 15

Which of the following would most likely decrease the velocity of a skeletal muscle contraction?

Accepted Answer

Increasing the load on the muscle.

Question 16

Which event marks the beginning of the power stroke in the cross bridge cycle?

Accepted Answer

Release of ADP and inorganic phosphate from the myosin head.

Question 17

In a real-life scenario, a sprinter relies primarily on which type of muscle fiber during a 100-meter dash?

Accepted Answer

Fast glycolytic fibers

Question 18

Which of the following is a direct result of acetylcholine binding to receptors on the muscle fiber membrane?

Accepted Answer

Opening of sodium channels and depolarization of the sarcolemma.

Question 19

Which formula best describes the calculation of muscle tension ($$T) $$generated by multiple motor units?

Accepted Answer

$$T = n 	imes t_{single}$$

Question 20

Which of the following factors does NOT influence the duration of a skeletal muscle contraction?

Accepted Answer

The color of the muscle fiber.

Chapter 9.2 Study Guide

Guida di studio - Domande di pratica