Question 1

Which of the following correctly lists the steps of the muscle contraction cycle in order?

Accepted Answer

Active-site exposure $$\rightarrow$$ Cross-bridge formation $$\rightarrow$$ Myosin head pivoting $$\rightarrow$$ Cross-bridge detachment $$\rightarrow$$ Myosin reactivation

Question 2

Which type of muscle is responsible for the involuntary movement of substances through the intestines?

Accepted Answer

Smooth muscle

Question 3

Which protein covers the active sites of actin in resting muscle fibers?

Accepted Answer

Tropomyosin

Question 4

Which of the following is NOT a component of the sarcomere?

Accepted Answer

Glycogen stores

Question 5

How do convergent muscles adapt to different activities?

Accepted Answer

By changing the direction they pull

Question 6

Which of the following muscles is correctly matched with its corresponding compartment?

Accepted Answer

Biceps femoris - Posterior compartment of thigh

Question 7

Which of the following is an example of a first-class lever in the human body?

Accepted Answer

Tipping the head backward

Question 8

Which of the following muscles has its origin, insertion, and action incorrectly paired?

Accepted Answer

Masseter: Origin - maxilla and mandible near molar; Insertion - orbicularis oris; Action - hip extension, cheek compression

Question 9

When the prime mover muscle is active, which type of muscle fibers are stretched and relaxed?

Accepted Answer

Antagonists

Question 10

A shift in membrane potential toward a more positive value is called:

Accepted Answer

Depolarization

Question 11

In which region of a neuron does an action potential usually start?

Accepted Answer

Axon hillock

Question 12

Which ion is primarily responsible for the initiation of the action potential in neurons?

Accepted Answer

Sodium ($$\mathrm{Na^+})$$

Question 13

Continuous propagation cannot occur in myelinated axons because:

Accepted Answer

Only the nodes without voltage-gated channels can respond to stimulus

Question 14

Cardiac muscle cells can generate action potentials spontaneously without external nervous input. This is due to which of the following specialized cells?

Accepted Answer

Pacemaker cells

Question 15

A neuron is at rest if the inside of the cell is:

Accepted Answer

More negative than the outside

Question 16

Which of the following describes the absolute refractory period?

Accepted Answer

It happens when the neuron is completely insensitive to a second stimulus.

Question 17

A patient is experiencing muscle weakness due to a defect in the protein that covers the active sites of actin. Which protein is most likely affected?

Accepted Answer

Tropomyosin

Question 18

During the depolarization phase of an action potential, which equation best describes the movement of sodium ions across the membrane?

Accepted Answer

$$I_{Na} = g_{Na}(V - E_{Na})$$

Question 19

If a muscle fiber cannot relax after contraction, which phase of the contraction cycle is most likely impaired?

Accepted Answer

Cross-bridge detachment

Question 20

A patient with multiple sclerosis has demyelinated axons. Which effect on action potential propagation is most likely?

Accepted Answer

Saltatory conduction is impaired, leading to slower nerve impulses.

Muscle and Nervous System Fundamentals: Study Notes for Anatomy & Physiology

Guida di studio - Domande di pratica

Study guide - Flashcard