Question 1

Which of the following best describes the function of the troponin-tropomyosin complex in skeletal muscle contraction?

Accepted Answer

It binds calcium ions, causing a conformational change that exposes myosin-binding sites on actin.

Question 2

During the contraction of a sarcomere, which regions decrease in length?

Accepted Answer

I band and H zone

Question 3

A patient presents with muscle rigidity after death (rigor mortis). Which of the following best explains why the myosin heads remain bound to actin in this state?

Accepted Answer

ATP is unavailable, so myosin heads cannot detach from actin.

Question 4

Which of the following is the correct equation for cardiac output ($$CO$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 5

A muscle is stretched beyond its optimal length before contraction. What is the most likely effect on force generation, and why?

Accepted Answer

Force decreases because there is less overlap between actin and myosin filaments.

Question 6

Which of the following best describes the sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Ach release → Action potential in sarcolemma → Ca$$^{2+}$$ release from SR → Cross-bridge cycling

Question 7

Which of the following is the correct equation for ejection fraction ($$EF$$)?

Accepted Answer

$$EF = \frac{SV}{EDV}$$

Question 8

Which of the following muscle fiber types is most resistant to fatigue and why?

Accepted Answer

Type I fibers, because they have abundant mitochondria and myoglobin.

Question 9

During the cardiac cycle, which valves are open during ventricular filling (phase 1)?

Accepted Answer

Atrioventricular (AV) valves

Question 10

Which of the following best explains why the speed of muscle shortening decreases as load increases?

Accepted Answer

Heavier loads slow the rate of cross-bridge cycling.

Question 11

Which of the following is the correct definition of stroke volume ($$SV$$)?

Accepted Answer

$$SV = EDV - ESV$$

Question 12

A patient has a heart rate of 80 beats per minute and a stroke volume of 70 mL. What is their cardiac output ($$CO$$)?

Accepted Answer

$$CO = 5600\ 	ext{mL/min}$$

Question 13

Which of the following best describes the role of the ryanodine receptor in muscle contraction?

Accepted Answer

It is a calcium channel in the sarcoplasmic reticulum that releases Ca$$^{2+}$$ into the sarcoplasm.

Question 14

Which of the following is true regarding isometric muscle contractions?

Accepted Answer

The muscle generates force without changing length.

Question 15

Which of the following best describes the order of motor unit recruitment during increasing muscle force?

Accepted Answer

Small, slow-twitch motor units are recruited first, followed by larger, fast-twitch units.

Question 16

Which of the following is the correct equation for mean arterial pressure ($$MAP$$)?

Accepted Answer

$$MAP = CO 	imes TPR$$

Question 17

Which of the following best describes the effect of sympathetic stimulation on the SA node?

Accepted Answer

It increases the frequency of action potentials, raising heart rate.

Question 18

Which of the following is a characteristic of cardiac muscle that distinguishes it from skeletal muscle?

Accepted Answer

Cardiac muscle cells are connected by intercalated discs containing gap junctions.

Question 19

Which of the following best describes the function of the 'funny' channels in pacemaker cells?

Accepted Answer

They allow Na$$^+$$ influx, contributing to spontaneous depolarization.

Question 20

Which of the following best explains why the atrioventricular (AV) valves close at the beginning of ventricular systole?

Accepted Answer

Ventricular pressure exceeds atrial pressure.

Comprehensive Study Guidance for Muscle and Cardiac Physiology (ANP)

Study Guide - Practice Questions

Study Guide - Flashcards