Question 1

The microcirculation is composed of:

Accepted Answer

The microcirculation is composed of arterioles, capillaries, and venules. Arteries and veins are part of the macrocirculation.

Question 2

Which is true of blood pressure:

Accepted Answer

Blood pressure decreases as the distance from the heart increases. This is due to the loss of pressure as blood moves through the vessels and encounters resistance from the vessel walls.

Question 3

The major function of the arterioles is to

Accepted Answer

Arterioles have two major functions: regulating the flow of blood through capillary beds and distributing the cardiac output to tissues. They do this by adjusting their diameter and resistance, which controls the amount of blood flowing through them. Arterioles also help to maintain blood pressure and can act as a pressure reservoir, storing blood during systole and releasing it during diastole. Therefore, option E, which includes both (a) and (b) above, is the best choice for the major function of arterioles.

Question 4

Which is not true of blood pressure:

Accepted Answer

Parasympathetic activity generally decreases heart rate and does not directly increase blood pressure.

Question 5

Blood flow is affected by

Accepted Answer

Blood flow is affected by all of these factors. Pressure differences between regions of the circulatory system drive blood flow. The viscosity of the blood, or its thickness and stickiness, can affect how easily blood flows through vessels. Friction between the blood and the walls of the vessels can also affect blood flow, as can the length and diameter of the vessels themselves.

Question 6

In an arteriole, if the blood vessel radius is 2 units and then vasoconstricted to 1 units, the resistance:

Accepted Answer

The resistance in a blood vessel is inversely proportional to the fourth power of the radius (Poiseuille's Law). Halving the radius increases resistance by 16 times. This increased resistance decreases blood flow.

Question 7

Resistance

Accepted Answer

Resistance (R) is directly proportional to the viscosity and length of the vessel, and inversely proportional to the fourth power of the radius of the vessel. Therefore, if the radius is reduced by one-half (i.e. 0.5), the resistance will increase (0.5)^4 or 16-fold (option C is correct). Also, option A is correct because resistance is a measure of the hindrance to blood flow due to friction between the moving fluid and stationary vascular walls. Therefore, both options A and C are correct, providing the answer E. Option B is incorrect because if the radius is reduced by one-half, the resistance will increase 16-fold (not double).

Question 8

Resistance increases when

Accepted Answer

According to Poiseuille's law, the resistance of a vessel is directly proportional to the length of the vessel and viscosity of the fluid, but inversely proportional to the radius of the vessel to the fourth power. Therefore, when the radius decreases, the resistance increases.

Question 9

A constant blood supply to this organ is a priority of the circulatory system:

Accepted Answer

The brain is one of the most metabolically active organs in the body and requires a constant blood supply to maintain adequate oxygen and nutrient delivery. Even a brief interruption of blood flow to the brain can cause significant neurological damage.

Question 10

Which of the following factors would produce the greatest change in blood flow?

Accepted Answer

According to Poiseuille's Law, Blood Flow = (π × r ⁴ × ΔP) / (8 × η × L). Doubling the radius of the vessel has the greatest effect on blood flow as it is raised to the fourth power in the equation, while the other factors have a linear or squared relationship with blood flow.

Question 11

Organs that recondition the blood

Accepted Answer

Reconditioning organs like the kidneys and liver receive a large percentage of cardiac output and can tolerate temporary reductions in blood flow better than non-reconditioning organs.

Question 12

Vasoconstriction

Accepted Answer

Vasoconstriction occurs when there is a decrease in the radius of a vessel, which increases resistance.

Answer: D
 Vasoconstriction occurs when there is a decrease in the radius of a vessel, which increases resistance. It can be due to a decrease in sympathetic activity, but this is not always the case. Therefore, options A and C are not always true.

Question 13

Of the following, which is most important in affecting vessel resistance?

Accepted Answer

The diameter of a blood vessel, also known as its radius, has the greatest impact on vessel resistance. This is due to the fact that vessel resistance is directly proportional to the fourth power of the vessel radius. Therefore, even small changes in vessel diameter can have a significant impact on vessel resistance. The other factors listed (length of a blood vessel, nature of blood flow, viscosity of the blood) can also affect vessel resistance, but to a lesser extent.

Question 14

The larger arteries assist with systemic blood flow to tissues by:

Accepted Answer

Elastic recoil of the walls of larger arteries helps to maintain blood flow through continuous propulsion of blood, even during periods of relaxation.

Question 15

Vasoconstriction

Accepted Answer

Vasoconstriction refers to a decrease in the radius of a vessel, and it causes a decrease in blood flow through that vessel. However, vasoconstriction of arterioles is controlled by the sympathetic system, not the parasympathetic system.

Question 16

Which type of blood vessel sometimes contains valves?

Accepted Answer

Veins are the only type of blood vessel that contain valves. These valves prevent backflow of blood and help to maintain blood flow towards the heart. Arteries and arterioles do not contain valves, while capillaries do not have enough pressure to require valves.

Question 17

Vascular resistance is most influence by:

Accepted Answer

Vascular resistance is directly proportional to the diameter of a blood vessel. A smaller diameter results in greater resistance to blood flow, while a larger diameter results in less resistance. The length of a blood vessel and the viscosity of the blood also affect the resistance, but to a lesser extent. The nature of the blood flow is not a major factor in determining vascular resistance. Therefore, the most influential factor in vascular resistance is the diameter of the blood vessel.

Question 18

Which of the following is the correct relationship between pressure, flow, and resistance?

Accepted Answer

The answer of Which of the following is the correct...

Question 19

Because the arteries have large radii, they serve as excellent rapid-transit passageways for blood. Their second function, related to their elasticity, is to act as a(n) ____ for maintaining blood flow during diastole.

Accepted Answer

Arteries act as a pressure reservoir due to their elasticity, which helps maintain blood flow during diastole when the heart is not actively pumping.

Question 20

The arteries

Accepted Answer

Arteries carry blood away from the heart to the tissues, not from the tissues to the heart. They are not a blood reservoir, do not have high resistance, and are not the site of exchange (capillaries are).

Quiz 10: The Blood Vessels and Blood Pressure

The microcirculation is composed of:

Which is true of blood pressure:

The major function of the arterioles is to

Which is not true of blood pressure:

Blood flow is affected by

In an arteriole, if the blood vessel radius is 2 units and then vasoconstricted to 1 units, the resistance:

Resistance

Resistance increases when

A constant blood supply to this organ is a priority of the circulatory system:

Which of the following factors would produce the greatest change in blood flow?

Organs that recondition the blood

Vasoconstriction

Of the following, which is most important in affecting vessel resistance?

The larger arteries assist with systemic blood flow to tissues by:

Vasoconstriction

Which type of blood vessel sometimes contains valves?

Vascular resistance is most influence by:

Which of the following is the correct relationship between pressure, flow, and resistance?

Because the arteries have large radii, they serve as excellent rapid-transit passageways for blood. Their second function, related to their elasticity, is to act as a(n) ____ for maintaining blood flow during diastole.

The arteries