$CO = 80 \times 70 = 5600\ \mathrm{mL/min}$

Question 1

Which protein directly binds calcium to initiate skeletal muscle contraction?

Accepted Answer

Troponin

Question 2

During the cardiac cycle, which event is responsible for the first heart sound (S1)?

Accepted Answer

AV valves closing

Question 3

Which phase of the ECG corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 4

If a patient’s end-diastolic volume (EDV) is 120 mL and end-systolic volume (ESV) is 50 mL, what is their stroke volume (SV)?

$SV = EDV - ESV$

Accepted Answer

$SV = 120 - 50 = 70\ \mathrm{mL}$

Question 5

Which of the following best describes the role of ATP in muscle contraction?

Accepted Answer

ATP hydrolysis detaches myosin from actin

Question 6

A patient has a heart rate (HR) of 80 beats/min and a stroke volume (SV) of 70 mL/beat. What is their cardiac output (CO)?

$CO = HR 	imes SV$

Accepted Answer

$CO = 80 	imes 70 = 5600\ \mathrm{mL/min}$

Question 7

Which of the following would increase blood flow according to Poiseuille’s Law?

$Q = \dfrac{\Delta P \cdot r^4}{8 \eta l}$

Accepted Answer

Increasing pressure gradient ($\Delta P$)

Question 8

Which ion is primarily responsible for the rapid depolarization phase in cardiac pacemaker cells?

Accepted Answer

Calcium ($Ca^{2+}$)

Question 9

What is the correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential → calcium release → troponin binds calcium → tropomyosin moves → myosin binds actin

Question 10

Which structure delays the electrical impulse in the heart to allow ventricular filling?

Accepted Answer

AV node

Question 11

A patient’s ECG shows a missing P wave. Which cardiac event is most likely affected?

Accepted Answer

Atrial depolarization

Question 12

Which of the following would most likely decrease cardiac output?

Accepted Answer

Decreased stroke volume

Question 13

Which neurotransmitter is released by the parasympathetic nervous system to decrease heart rate?

Accepted Answer

Acetylcholine

Question 14

During isovolumetric contraction, which valves are open?

Accepted Answer

All valves are closed

Question 15

Which of the following best explains why ventricular repolarization is not visible as a distinct wave in the ECG?

Accepted Answer

Atrial repolarization is hidden in the QRS complex, not ventricular repolarization

Question 16

Which of the following would most likely increase the force of cardiac contraction?

Accepted Answer

Increased sympathetic stimulation

Question 17

If a patient’s cardiac output is 5 L/min and their heart rate is 100 beats/min, what is their stroke volume?

$CO = HR 	imes SV \implies SV = \dfrac{CO}{HR}$

Accepted Answer

$SV = \dfrac{5}{100} = 0.05\ \mathrm{L/beat}$

Question 18

Which of the following is a function of the sarcoplasmic reticulum in skeletal muscle?

Accepted Answer

Storing and releasing calcium ions

Question 19

Which of the following would most likely result from a blockage in the bundle of His?

Accepted Answer

Delayed ventricular contraction

Question 20

Which of the following best describes the Frank-Starling law of the heart?

Accepted Answer

The greater the stretch of cardiac muscle fibers, the greater the force of contraction

Human Physiology: Skeletal Muscle & Cardiovascular System Study Guide

Study Guide - Practice Questions