Question 1

Which of the following statements concerning control of blood flow through arterioles is TRUE?

Accepted Answer

Arterioles in an organ will dilate in response to a sudden decrease in arterial blood pressure to the organ, as part of an autoregulatory mechanism to maintain blood flow to the organ.

Question 2

Which of the following correctly compares the factors involved in bulk flow of fluid in systemic and pulmonary capillaries?

Accepted Answer

The hydrostatic pressure inside pulmonary capillaries is significantly lower than outside pressure, allowing for filtration of fluid out of capillaries and into the lung interstitium. In contrast, systemic capillaries have a higher hydrostatic pressure, which favors filtration out of capillaries and into the tissues. The protein oncotic pressure is similar in both types of capillaries, and lymphatic vessels are present in both the systemic and pulmonary circulatory systems. Therefore, Choices A, B, D, and E are incorrect.

Question 3

Following hemorrhage, reflexes are triggered that attempt to compensate for the blood loss. As a result of the blood loss and the reflex mechanisms, which of the following will be TRUE, compared to pre-hemorrhage values?

Accepted Answer

Following hemorrhage, both cardiac output and total peripheral resistance will decrease due to the reduction in blood volume. The body's reflex mechanisms will attempt to compensate for the blood loss by increasing sympathetic activity, which will increase heart rate and contractility, and vasoconstriction, which will increase total peripheral resistance. However, this compensatory response will not be enough to fully compensate for the blood loss, leading to a decrease in both cardiac output and total peripheral resistance. Therefore, choice D is the correct answer. Hematocrit may increase as a result of hemoconcentration due to the loss of plasma volume, but this is not a universal response and it is not a reliable indicator of compensation for hemorrhage.

Question 4

Which is the most likely effect of physical endurance training on a person's cardiac performance?

Accepted Answer

Physical endurance training leads to an increase in maximal stroke volume, which is the amount of blood pumped from the heart with each contraction. This is due to strengthening of the heart muscle and improved venous return. An increase in cardiac output would also be possible, but only during exercise, not at rest. Maximal heart rate may not necessarily increase, as it is largely determined by an individual's genetics. Resting heart rate may decrease with endurance training, as the heart becomes more efficient.

Question 5

Which of the following factors would NOT tend to increase systemic arterial blood pressure?

Accepted Answer

Increased parasympathetic stimulation of the heart would actually decrease heart rate and cardiac output, leading to a decrease in arterial blood pressure.

Question 6

Distinguishing characteristics of veins include which of the following?

Accepted Answer

The answer of Distinguishing characteristics of veins include which of...

Question 7

Which is a typical response of the body to hemorrhage?

Accepted Answer

During hemorrhage, the body compensates by increasing reabsorption of fluid into capillaries to maintain blood volume and pressure.

Question 8

What determines the movement of blood in systemic veins?

Accepted Answer

All of the listed factors contribute to the movement of blood in systemic veins. The blood pressure difference between systemic capillaries and the right atrium drives the initial movement of blood, while the contraction and relaxation of skeletal muscles help to propel it forward. The decrease of thoracic pressure and increase of abdominal pressure due to diaphragm movement also aid in venous return, and valves in the veins prevent backflow of blood.

Question 9

Which of the following statements concerning the capillaries is FALSE?

Accepted Answer

Increasing capillary hydrostatic pressure increases the likelihood that filtration will occur.

Question 10

Which of the following is a result of increased sympathetic stimulation of vascular smooth muscle?

Accepted Answer

Increased sympathetic stimulation of vascular smooth muscle causes vasoconstriction, which increases venous return of blood to the heart. This occurs because the constriction of veins, particularly in the legs, helps to propel blood back toward the heart, thereby increasing the amount of blood that is returned to the heart with each heartbeat. Choices A, B, C, and D are not correct because increased sympathetic stimulation of vascular smooth muscle would not result in these outcomes.

Question 11

Jane donates a pint of blood to a blood bank. A few minutes later, which of the following would be increased compared to pre-donation values?

Accepted Answer

After donating blood, Jane's heart rate increases to maintain cardiac output despite the reduced blood volume, and total peripheral resistance increases to help maintain blood pressure.

Question 12

Jane donates a pint of blood to a blood bank. A few minutes later, which of the following would be decreased compared to pre-donation values?

Accepted Answer

After donating blood, the body prioritizes maintaining blood flow to vital organs like the brain and heart. Blood flow to the kidneys is reduced to conserve blood volume, decreasing the percentage of cardiac output to the kidneys.

Question 13

Normally, the hydrostatic pressure difference between capillary fluid and interstitial fluid favors movement of fluid ________ a tissue capillary. The protein osmotic pressure difference between capillary fluid and interstitial fluid normally favors movement of fluid __________ a tissue capillary.

Accepted Answer

The hydrostatic pressure difference favors movement of fluid out of a tissue capillary into the interstitial fluid. This is because there is greater hydrostatic pressure in the capillary compared to the interstitial fluid. 
The protein osmotic pressure difference favors movement of fluid into a tissue capillary from the interstitial fluid. This is because there is greater osmotic pressure in the capillary due to the presence of proteins, which attract water molecules. So, fluid moves from the area of lower osmotic pressure (interstitial fluid) to the area of higher osmotic pressure (capillary fluid). Therefore, the correct answer is option D, which is out of; into.

Question 14

During exercise, there is a decreased flow of blood to:

Accepted Answer

During exercise, the body prioritizes blood flow to the skeletal muscles, skin (for heat dissipation), and heart to support increased activity and oxygen demand. Blood flow to the abdominal organs decreases as the body reallocates resources to support the heightened activity.

Question 15

Blood flow through most organs in the systemic circuit is regulated primarily by increasing or decreasing the ________ activity to arteriolar smooth muscles in the organ. Another form of regulation, called ________, depends upon the metabolic activity of the organ. Increased activity leads to increased interstitial fluid metabolites, which cause ___ of the arterioles. The former is a type of ________ regulation of blood flow; the latter is an example of ________ regulation.

Accepted Answer

The first blank is filled by "sympathetic" because sympathetic nerve activity causes vasoconstriction or vasodilation in response to changes in blood pressure or metabolic demand. The second blank is filled by "active hyperemia" because this type of regulation occurs when the metabolic rate of an organ increases, leading to increased blood flow to meet the higher demand. The third blank is filled by "dilation" because increased metabolic activity leads to increased levels of vasodilator metabolites, causing dilation of arterioles to increase blood flow. The fourth blank is filled by "extrinsic" because sympathetic regulation of blood flow is an extrinsic mechanism involving the nervous system. The fifth blank is filled by "intrinsic" because metabolic regulation of blood flow is an intrinsic mechanism within the organ itself.

Question 16

How would a hemorrhage immediately affect the activity of the baroreceptors?

Accepted Answer

A hemorrhage decreases blood volume and thus decreases blood pressure. This would cause a decrease in firing rate of the baroreceptors, which are sensitive to changes in blood pressure. A decrease in firing rate of the baroreceptors would lead to a decrease in the activity of all medullary cardiovascular center cell types, as these cells receive input from the baroreceptors. This would result in an overall increase in sympathetic activity and decrease in parasympathetic activity, which would be necessary to increase cardiac output and maintain blood pressure in response to the hemorrhage.

Question 17

Which of the following is most likely to occur when a soldier stands at attention--very still, with legs and spine straight?

Accepted Answer

When standing still, gravity causes blood to pool in the veins of the feet and legs, leading to increased storage of blood in these areas.

Question 18

Which of the following does NOT contribute to increased stroke volume during exercise?

Accepted Answer

During exercise, the heart rate and contractility increase, leading to increased stroke volume. Increased venous return (B) leads to increased preload, which stretches the ventricle and increases stroke volume through the Frank-Starling mechanism. Increased contractility of cardiac muscle (A) and sympathetic stimulation of ventricular muscle (D) both increase the force of contraction, leading to increased stroke volume. Increased end-diastolic volume (E) also stretches the ventricle and increases stroke volume through the Frank-Starling mechanism. However, increased length of filling time during diastole (C) does not contribute to increased stroke volume; in fact, a shorter diastolic filling time can increase stroke volume by increasing heart rate and contractility.

Question 19

Which of the following is most likely to be a cause of hypotension?

Accepted Answer

Sweating, vomiting, or emotional responses can lead to fluid loss or vasodilation, which can decrease blood pressure, causing hypotension.

Question 20

If the arterial blood pressure in the brain is suddenly decreased, the flow through arterioles in the brain will immediately fall and then which of these will occur next?

Accepted Answer

The decrease in arterial blood pressure will initially cause a decrease in flow through brain arterioles. However, flow autoregulation mechanisms in the brain will eventually cause compensation, leading to a return of blood flow toward its original level. Brain arterioles will not constrict, dilate, or experience reactive hyperemia. There is also no evidence to suggest that excess CO₂ levels would be involved in this scenario.

Quiz 12: Cardiovascular Physiology