Question 1

Isovolumetric contraction appears on the ECG as part of the QRS complex.

Accepted Answer

Isovolumetric contraction does not appear on the ECG as it refers to the period in the cardiac cycle where the ventricles are contracting but the volume of blood is not changing, and this does not produce any electrical activity that can be detected by the ECG. The QRS complex represents the depolarization of the ventricles, which precedes the beginning of the isovolumetric contraction.

Question 2

An increase in afterload will cause the heart to remain longer in the period of isovolumetric contraction.

Accepted Answer

Afterload is the resistance that the heart has to overcome to eject blood from the ventricles. An increase in afterload can occur due to narrowing of blood vessels, increased blood pressure, or other factors. This increased resistance means that the heart has to generate more pressure to overcome it, leading to a longer period of isovolumetric contraction (when the ventricles are contracting but no blood is leaving the chamber). This allows the heart to build up enough pressure to overcome the increased afterload and open the valves to eject the blood. Therefore, an increase in afterload will cause the heart to remain longer in the period of isovolumetric contraction.

Question 3

Cardiac output is equal to (EDV-ESV) times the number of heart beats per minute

Accepted Answer

This is the correct formula for calculating cardiac output, where EDV is end-diastolic volume and ESV is end-systolic volume.

Question 4

Stroke volume is inversely correlated to preload; i.e., a lower preload increases stroke volume.

Accepted Answer

Stroke volume is directly related to preload, meaning that a higher preload leads to a higher stroke volume. This is because preload refers to the amount of blood filling the heart before it contracts, and a greater volume of blood provides more stretch on the heart muscle, allowing for a stronger contraction and a larger stroke volume.

Question 5

An increase in afterload will cause the heart to remain longer in the period of isovolumetric relaxation.

Accepted Answer

An increase in afterload affects the period of isovolumetric contraction, not relaxation, as the heart must generate more pressure to open the aortic valve.

Question 6

Most blood flow through the coronary vessels occurs during ventricular systole when the heart is driving blood forward.

Accepted Answer

Most blood flow through the coronary vessels occurs during ventricular diastole when the heart muscle is relaxed, allowing the coronary vessels to fill with blood. During systole, the contraction of the heart muscle compresses the coronary vessels, reducing blood flow.

Question 7

Parasympathetic stimulation of the heart increases cardiac reserve by allowing more time for the heart to relax between contractions.

Accepted Answer

The answer of Parasympathetic stimulation of the heart increases cardiac...

Question 8

L-type calcium channels allow the refractory periods in the heart's contractile cells to be about as long as the cells' relaxation periods.

Accepted Answer

L-type calcium channels play a crucial role in regulating the duration of cardiac action potentials, allowing for efficient excitation-contraction coupling and proper cardiac rhythm. They contribute to the refractory period of contractile cells, which is about as long as the cells' relaxation periods, preventing premature depolarization and ensuring that the heart beats properly.

Question 9

The ECG allows one to detect the electrical activity of a single contractile cell in the heart, but it does not show any mechanical events such as contraction and relaxation.

Accepted Answer

The ECG does not show mechanical events such as contraction and relaxation, but it does show the electrical activity of the entire heart, not just a single contractile cell.

Question 10

During congestive heart failure, the heart is pumping out deoxygenated at a faster rate than it is pumping out oxygenated blood.

Accepted Answer

During congestive heart failure, the heart is unable to pump enough oxygenated blood to meet the body's needs. This causes the heart to pump faster in an attempt to compensate, but this only leads to further deoxygenation of the blood.

Question 11

The Frank-Starling law of the heart relates to how stretching of the ventricles during ventricular filling will affect stroke volume.

Accepted Answer

The Frank-Starling law states that as the ventricles fill with more blood, the myocardial fibers stretch and contract with greater force, resulting in increased stroke volume.

Question 12

An stationary embolus in a pulmonary artery could break loose and travel as a thrombus where it could stop up a smaller blood vessel in the lung.

Accepted Answer

The answer of An stationary embolus in a pulmonary artery...

Question 13

The heart utilizes glucose almost exclusively for energy production.

Accepted Answer

The heart primarily uses fatty acids for energy production, although it can also utilize glucose and lactate, especially under certain conditions like increased workload or ischemia.

Question 14

Not all forms of cholesterol are equally harmful to the heart.

Accepted Answer

There are two types of cholesterol - HDL (high-density lipoprotein) and LDL (low-density lipoprotein). HDL is considered "good" cholesterol because it helps remove LDL, which is considered "bad" cholesterol, from the bloodstream. Therefore, higher levels of HDL and lower levels of LDL are better for heart health.

Question 15

Oxygenated blood would pass through the mitral valve and pulmonary valves, but would not pass through the tricuspid valve.

Accepted Answer

Oxygenated blood would pass through the mitral valve and aortic valve, not the pulmonary valve. The tricuspid valve is responsible for regulating the flow of deoxygenated blood into the right ventricle, which is then pumped to the lungs via the pulmonary artery.

Question 16

According to the Frank-Starling law of the heart, the shorter the initial length of the cardiac muscle fibers prior to contraction, the more forceful will be the subsequent contraction because the fibers are already partially contracted.

Accepted Answer

According to the Frank-Starling law of the heart, the longer the initial length of the cardiac muscle fibers prior to contraction, the more forceful will be the subsequent contraction. This is because a greater stretch of the fibers leads to a greater overlap of the actin and myosin filaments, allowing for more forceful contractions.

Question 17

Increased EDV results in decreased stroke volume, and increased stroke volume results in increased ESV.

Accepted Answer

Increased EDV (end-diastolic volume) actually leads to an increase in stroke volume due to the Frank-Starling mechanism, where increased preload (EDV) results in greater stretch of the ventricular walls and stronger contraction. Similarly, increased stroke volume leads to a decrease in ESV (end-systolic volume) as the ventricle ejects more blood during systole, leaving less blood remaining in the chamber at the end of contraction. Therefore, the statement is false.

Question 18

An increase in venous return would increase preload and decrease ESV.

Accepted Answer

An increase in venous return leads to an increase in end-diastolic volume (EDV), which in turn leads to an increase in preload. This results in an increase in stroke volume and a decrease in end-systolic volume (ESV).

Question 19

The ____________________ is the normal pacemaker of the heart.

Accepted Answer

The answer of The ____________________ is the normal pacemaker of...

Question 20

Left-sided congestive heart failure can lead to pulmonary edema.

Accepted Answer

Left-sided congestive heart failure can cause blood to back up into the lungs, leading to pulmonary edema which is a buildup of fluid in the lungs.

Quiz 9: Cardiac Physiology