Question 1

Compared to cardiac muscle tissue, skeletal muscle tissue has a(n) ____________________ duration for its refractory period.

Accepted Answer

The answer of Compared to cardiac muscle tissue, skeletal muscle...

Question 2

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

Accepted Answer

The Frank-Starling law of the heart states that the longer the initial length of the cardiac muscle fibres prior to contraction, the more forceful will be the subsequent contraction. This is because the sarcomeres in the muscle fibres have greater overlap, which allows for a stronger interaction between actin and myosin filaments during contraction. Therefore, a longer initial length leads to a stronger contraction, not a shorter initial length.

Question 3

HDLs have less protein than LDLs.

Accepted Answer

HDLs have more protein compared to LDLs, which have more cholesterol and triglycerides.

Question 4

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

Accepted Answer

LDL cholesterol particles vary in size, density and composition, and some types are more harmful than others. Smaller, denser LDL particles are associated with a higher risk of heart disease compared to larger, buoyant LDL particles.

Question 5

According to the Frank-Starling law of the heart, the greater the stroke volume, the smaller the subsequent end-diastolic volume will be, because as more blood is squeezed out, the heart cannot fill as completely during the next diastole.

Accepted Answer

The Frank-Starling law of the heart actually states that the greater the volume of blood entering the heart during diastole (end-diastolic volume), the greater the volume of blood ejected by the heart during systole (stroke volume) due to the increased stretch of cardiac muscle fibers, not that a greater stroke volume leads to a smaller subsequent end-diastolic volume.

Question 6

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

Accepted Answer

Left-sided congestive heart failure occurs when the left ventricle cannot pump enough blood to meet the body's needs, causing blood to back up into the lungs. This can lead to pulmonary edema, which is fluid accumulation in the lungs.

Question 7

The cardiac output is the same as the cardiac reserve of the heart.

Accepted Answer

The cardiac output is the amount of blood pumped by the heart per minute, while the cardiac reserve refers to the ability of the heart to respond to increased demands for oxygen and nutrients. They are not the same thing.

Question 8

The ____________________ ensures that atrial excitation and contraction are complete before ventricular excitation and contraction commence.

Accepted Answer

The answer of The ____________________ ensures that atrial excitation and...

Question 9

Angina pectoris develops from the abundance of oxygen of blood in the coronary circulation.

Accepted Answer

Angina pectoris develops from a lack of oxygen supply to the heart muscle, usually due to blockages or narrowing in the coronary arteries.

Question 10

Cardiac output is stroke volume times the heart rate.

Accepted Answer

Cardiac output is calculated as the amount of blood pumped by the heart per minute, which is equal to the stroke volume (the amount of blood ejected by the heart in one beat) multiplied by the heart rate (the number of beats per minute).

Question 11

The heart utilizes glucose almost exclusively for energy production.

Accepted Answer

The heart primarily uses fatty acids for energy production, although it can also use glucose, lactate, and ketone bodies depending on availability and conditions.

Question 12

The heart muscle receives its oxygen and nutrients directly from the blood within its chambers during ventricular diastole.

Accepted Answer

The heart muscle, or myocardium, receives its oxygen and nutrients from the blood flowing through the coronary arteries, not directly from the blood within its chambers.

Question 13

The ____________________ is the normal pacemaker of the heart.

Accepted Answer

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

Question 14

The condition in which the pericardial sac becomes distended with excess fluid to the point that it impinges upon cardiac filling is known as ____________________.

Accepted Answer

The answer of The condition in which the pericardial sac...

Question 15

The amount of blood pumped out of the heart during each beat is known as the cardiac output.

Accepted Answer

The amount of blood pumped out of the heart during each beat is known as the stroke volume. Cardiac output is the volume of blood the heart pumps per minute, which is calculated as stroke volume times heart rate.

Question 16

Increased EDV results in decreased stroke volume.

Accepted Answer

Increased EDV typically results in increased stroke volume due to the Frank-Starling mechanism. When the heart is filled with a larger volume of blood (EDV), the myocardial fibers are stretched, which leads to a stronger contraction and a greater ejection of blood (stroke volume).

Question 17

Cardiac muscle receives its blood supply primarily during ventricular systole when blood is being pumped out into the aorta.

Accepted Answer

Cardiac muscle receives its blood supply primarily during ventricular diastole (relaxation phase) when the coronary arteries fill with blood. During ventricular systole (contraction phase), blood flow to the coronary arteries is actually reduced due to the compression of the vessels by the contracting heart muscle.

Question 18

The average resting heart rate is normally established by the rhythm of the AV node.

Accepted Answer

The average resting heart rate is actually established by the sinoatrial (SA) node, not the atrioventricular (AV) node. The SA node is responsible for initiating the electrical impulses that start each heartbeat.

Question 19

Ninety-nine percent of the cardiac fibres are specialized for ____________________ whereas the remainder are specialized for ____________________.

Accepted Answer

The answer of Ninety-nine percent of the cardiac fibres are...

Question 20

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 relaxes and the pressure in the heart chambers falls, allowing the coronary vessels to fill.

Quiz 8: Cardiac Physiology