Question 1

The difference between end-diastolic volume and end-systolic volume is known as:

Accepted Answer

The difference between end-diastolic volume (the amount of blood in the ventricles at the end of diastole) and end-systolic volume (the amount of blood remaining in the ventricles at the end of systole) is known as the stroke volume. The ejection fraction is the percentage of the end-diastolic volume that is ejected during systole, and is calculated as stroke volume divided by end-diastolic volume. Therefore, B is the best choice as ejection fraction relies on stroke volume, which is obtained from the difference between end-diastolic volume and end-systolic volume.

Question 2

Decreases in heart rate as a result of training is likely the result of:

Accepted Answer

Decreases in heart rate as a result of training is likely the result of both increased parasympathetic activity and decreased sympathetic activity. During exercise, sympathetic activity increases to increase heart rate, but with training, the body becomes more efficient at supplying oxygen to the muscles and doesn't need to work as hard, resulting in reduced sympathetic activity. Additionally, the parasympathetic nervous system, which slows down heart rate, can become more dominant with training, further contributing to the decrease in heart rate.

Question 3

Increases in stroke volume during the early phases of exercise are the result of an increase in left ventricular end-diastolic volume. This is a result of:

Accepted Answer

The Frank-Starling mechanism is the stretch-induced increase in force of contraction of the heart muscle. As the left ventricle fills with more blood during diastole, the muscle fibers are stretched and respond by contracting more forcefully, leading to an increase in stroke volume. This mechanism accounts for the initial increase in stroke volume during exercise. The Law of LaPlace and the Fick principle are not involved in this process, while the Bohr effect refers to the influence of pH on oxygen binding by hemoglobin.

Question 4

Which statement is not correct relating to cardiovascular changes during an acute exercise bout?

Accepted Answer

During an acute exercise bout, diastolic blood pressure typically remains relatively stable or may slightly decrease, rather than increasing at the beginning and then leveling off. The other options accurately describe cardiovascular responses to acute exercise.

Question 5

Oxygen dissociates from hemoglobin more rapidly when:

Accepted Answer

The Bohr effect states that a decrease in pH (or increase in acidity) results in the weakening of hemoglobin's affinity for oxygen, causing it to release oxygen more readily. This is why oxygen dissociates more rapidly from hemoglobin when pH levels are reduced.

Question 6

Maximal aerobic capacity is determined by:

Accepted Answer

Maximal aerobic capacity, often measured as VO2 max, is determined by the combination of cardiac output and the arteriovenous oxygen difference (a−v)O2 difference. Cardiac output reflects the volume of blood the heart pumps per minute, while the (a−v)O2 difference indicates the amount of oxygen extracted by the muscles from the blood. Together, these factors determine the body's capacity to deliver and utilize oxygen during maximal exercise.

Question 7

Concentric hypertrophy of the left ventricle is best described as:

Accepted Answer

Concentric hypertrophy of the left ventricle is characterized by an increase in wall thickness with no change in the internal diameter of the left ventricle. This type of hypertrophy is typically seen in response to pressure overload, such as hypertension or aortic stenosis, and is not related to endurance training.

Question 8

Which statement concerning cardiovascular changes to endurance training is not correct?

Accepted Answer

Although maximal heart rate can increase with training, it typically reaches its limit after several months of training and does not continue to increase over years.

Question 9

Which statement is most accurate concerning cardiovascular adaptations in a resistance-trained athlete?

Accepted Answer

Resistance training can lead to left ventricular hypertrophy, which means that the walls of the left ventricle increase in size. However, this is often accompanied by an increase in internal diameter, which allows for an increase in cardiac output. Therefore, option A and B are incorrect. Resting blood pressure can increase in individuals with high levels of muscularity, but it is not a consistent finding in all resistance-trained athletes. Therefore, option D is incorrect. Option C is the most accurate statement as it describes the most common cardiovascular adaptation seen in resistance-trained athletes, i.e., an increase in the thickness of the left ventricular walls with no change in internal diameter.

Question 10

Which of the following is not part of the conduction system in the heart?

Accepted Answer

The mitral valve is not part of the conduction system in the heart. It is one of the heart valves that helps to regulate blood flow between the left atrium and left ventricle, but it does not play a role in generating or conducting electrical impulses in the heart. The other options (sinoatrial node, atrioventricular node, bundle of His) are all part of the conduction system and are involved in regulating the heartbeat.

Question 11

Which answer is most correct concerning capillary microcirculation and oxygen diffusion?

Accepted Answer

Capillary microcirculation is characterized by a large surface area for gas exchange, slow rate of blood flow to ensure sufficient time for diffusion, and a thin layer of endothelial cells to facilitate the diffusion of oxygen and other gases. This is why option B, which describes these factors accurately, is the most correct answer.

Question 12

Adaptations to the morphology of the heart are governed by:

Accepted Answer

The law of LaPlace governs the adaptations to the morphology of the heart. This law states that wall stress in the heart is proportional to the pressure multiplied by the radius of the chamber, divided by the wall thickness. Therefore, as the heart grows larger to accommodate a greater workload, the walls must thicken in order to maintain wall stress within a safe range.

Question 13

When exercise is prolonged or performed in a hot environment an increase in heart rate may be seen with a concomitant decrease in stroke volume. This phenomenon is known as:

Accepted Answer

The phenomenon of an increase in heart rate and a concomitant decrease in stroke volume during prolonged exercise or in a hot environment is known as cardiac drift. This occurs as a result of an increase in core body temperature and dehydration which causes a decrease in blood volume and an increase in heart rate to maintain cardiac output.

Question 14

Which statement concerning exercising in the heat is not correct?

Accepted Answer

Evaporative cooling through sweating does not restore blood volume; it actually reduces blood volume as fluid is lost through sweat.

Question 15

Which of the following would be expected to occur during prolonged exposure to altitude?

Accepted Answer

At high altitudes, the body compensates for lower oxygen availability by increasing the production of red blood cells to enhance oxygen transport to tissues.

Question 16

Maximal heart rate can be elevated through prolonged, high intensity endurance training.

Accepted Answer

Maximal heart rate is largely determined by genetics and age, and can only be slightly increased through training. High intensity endurance training can improve cardiovascular fitness and efficiency, but it cannot significantly increase maximal heart rate.

Question 17

The sinoatrial node is also known as the pacemaker of the heart.

Accepted Answer

The sinoatrial node (SA node) is located in the right atrium of the heart and is responsible for initiating the electrical impulses that regulate the heartbeat. Due to its crucial role in setting the pace of the heartbeat, it is often referred to as the "pacemaker" of the heart.

Question 18

A reduction in resting heart rate is likely the result of increased sympathetic stimulation.

Accepted Answer

A reduction in resting heart rate is usually the result of increased parasympathetic stimulation and decreased sympathetic stimulation.

Question 19

The primary mechanism controlling oxygen diffusion from the capillaries to the tissues is pressure gradients created by the partial pressure of oxygen in each area.

Accepted Answer

Oxygen diffusion from the capillaries to the tissues is primarily controlled by pressure gradients created by the partial pressure of oxygen in each area.

Question 20

Systolic blood pressure will increase linearly during dynamic exercise.

Accepted Answer

During dynamic exercise, systolic blood pressure increases linearly as a result of increased cardiac output and peripheral vascular resistance.

Quiz 2: The Cardiorespiratory System