Question 1

Which of the following best describes the role of the Z disk in the sarcomere structure of skeletal muscle?

Accepted Answer

It anchors the thin filaments and marks the ends of each sarcomere.

Question 2

During muscle contraction, which sequence of events occurs first in skeletal muscle?

Accepted Answer

Depolarization of the motor end plate

Question 3

Which ion is primarily responsible for initiating contraction in both skeletal and cardiac muscle?

Accepted Answer

Calcium ($$Ca^{2+})$$

Question 4

What is the physiological significance of the Frank-Starling law in cardiac muscle?

Accepted Answer

It explains how increased venous return leads to increased stroke volume.

Question 5

Which of the following best describes the function of the SA node in the heart?

Accepted Answer

It acts as the primary pacemaker, generating spontaneous action potentials.

Question 6

Which equation correctly represents the calculation of mean arterial pressure (MAP)?

Accepted Answer

$$MAP = Diastolic\ Pressure + \frac{1}{3}(Systolic\ Pressure - Diastolic\ Pressure)$$

Question 7

Which of the following is TRUE regarding the role of calcium in cardiac muscle contraction compared to skeletal muscle?

Accepted Answer

In cardiac muscle, both extracellular and sarcoplasmic reticulum calcium contribute to contraction.

Question 8

Which of the following best explains the effect of increasing total peripheral resistance (TPR) on blood pressure?

Accepted Answer

Increasing TPR increases blood pressure by increasing afterload.

Question 9

A patient is experiencing bradycardia due to increased vagal tone. Which branch of the nervous system is responsible for this effect?

Accepted Answer

Parasympathetic nervous system

Question 10

Which of the following best describes the role of T-tubules in skeletal muscle contraction?

Accepted Answer

They transmit the action potential deep into the muscle fiber.

Question 11

Which of the following is a key difference between the action potential in cardiac muscle and skeletal muscle?

Accepted Answer

Cardiac muscle action potentials have a plateau phase due to calcium influx.

Question 12

Which of the following is TRUE regarding the role of voltage-gated sodium channels in cardiac muscle?

Accepted Answer

They initiate the rapid depolarization phase in ventricular myocytes.

Question 13

Which of the following best describes the effect of sympathetic stimulation on heart rate and contractility?

Accepted Answer

It increases heart rate and contractility by releasing norepinephrine.

Question 14

Which of the following is the correct order of events during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential travels down T-tubules, calcium is released from sarcoplasmic reticulum, calcium binds to troponin.

Question 15

A patient is found to have a mutation in the ryanodine receptor in cardiac muscle. Which process would be most directly affected?

Accepted Answer

Release of calcium from the sarcoplasmic reticulum during contraction

Question 16

Which of the following best explains why the refractory period in cardiac muscle is longer than in skeletal muscle?

Accepted Answer

To prevent tetanus and ensure proper filling of the heart chambers

Question 17

Which of the following is TRUE regarding the role of ATP in muscle contraction?

Accepted Answer

ATP is required for both the detachment of myosin from actin and the re-cocking of the myosin head.

Question 18

Which of the following best describes the effect of opening potassium channels during the cardiac action potential?

Accepted Answer

It leads to repolarization and restoration of the resting membrane potential.

Question 19

Which of the following is TRUE regarding the difference between autonomic and somatic motor neuron control of muscle?

Accepted Answer

Autonomic neurons control involuntary cardiac and smooth muscle contraction.

Cardiac and Skeletal Muscle Physiology: Structure, Function, and Control

Study Guide - Practice Questions