Question 1

For a blood pressure reading of 136/78 mmHg, 78 refers to the diastolic pressure.

Accepted Answer

In a blood pressure reading, the second number refers to the diastolic pressure, so in this case, 78 mmHg is the diastolic pressure.

Question 2

Histamine released in injured areas produces local arteriolar vasodilation.

Accepted Answer

Histamine is a potent vasodilator and causes arteriolar vasodilation in the area where it is released, leading to increased blood flow and inflammation.

Question 3

When the heart is not ejecting blood into the arterial system, the pressure in the arteries falls to zero as blood drains off into the rest of the vasculature.

Accepted Answer

When the heart is not ejecting blood into the arterial system, there is still pressure in the arteries from the previous beat. This is known as diastolic blood pressure. Therefore, the pressure in the arteries does not fall to zero.

Question 4

During exercise, blood flow to the digestive tract is increased by dilation of the arterioles of the digestive tract.

Accepted Answer

During exercise, blood flow is directed toward the muscles that are working and away from other organs, including the digestive tract. Arterioles in the digestive tract actually constrict to reduce blood flow to this area during exercise.

Question 5

If the diastolic pressure and systolic pressure were both increased by 18 mmHg, then the pulse pressure would be increased by 19 mmHg.

Accepted Answer

The pulse pressure is calculated by subtracting the diastolic pressure from the systolic pressure. If both pressures are increased by the same amount, the pulse pressure would remain the same.

Question 6

The pulse pressure is the maximum pressure exerted in the arteries.

Accepted Answer

Pulse pressure is the difference between the systolic (maximum) and diastolic (minimum) pressures in the arteries, not the maximum pressure itself.

Question 7

A local increase in potassium increases the vasodilation of arterioles.

Accepted Answer

An increase in potassium causes hyperpolarization of vascular smooth muscle cells, leading to vasodilation of arterioles.

Question 8

Using F = P/R, as resistance increases, the flow increases if the pressure is constant.

Accepted Answer

According to the formula F = P/R, if resistance increases, the flow decreases if the pressure is constant. This is because resistance is inversely proportional to flow rate, meaning as resistance increases, flow rate decreases.

Question 9

The mean arterial pressure is a simple average of the systolic and diastolic pressures.

Accepted Answer

The mean arterial pressure is not a simple average of the systolic and diastolic pressures but is calculated using a formula: MAP = diastolic pressure + 1/3(systolic pressure - diastolic pressure).

Question 10

Differences in blood flow to an organ are related to the resistance to flow offered by the arterioles that supply that organ.

Accepted Answer

The arterioles are the main site of vascular resistance, so differences in their resistance affect blood flow to a given organ. In other words, organs with higher arteriolar resistance will receive less blood flow than organs with lower arteriolar resistance.

Question 11

Local control mechanisms can override sympathetic control of changes in the size of arterioles.

Accepted Answer

Local control mechanisms such as metabolic factors and myogenic autoregulation can override sympathetic control of changes in the size of arterioles, allowing for local regulation of blood flow.

Question 12

Arterial walls contain a thick layer of smooth muscle and an abundance of collagen and elastin fibres.

Accepted Answer

Arterial walls do contain a thick layer of smooth muscle and an abundance of collagen and elastin fibres.

Question 13

Hyperaemia occurs in response to circulating epinephrine.

Accepted Answer

Hyperaemia is an increase in blood flow to different tissues in the body, often due to increased demand for oxygen or nutrients, not directly caused by circulating epinephrine.

Question 14

Increased sympathetic stimulation causes generalized vasoconstriction.

Accepted Answer

Increased sympathetic stimulation activates alpha-adrenergic receptors in blood vessels, causing vasoconstriction throughout the body. This helps to increase blood pressure and redirect blood flow to vital organs during times of stress or emergency.

Question 15

The greatest pressure drop in the vascular system occurs within the capillaries due to fluid leaving the capillaries by the process of ultrafiltration.

Accepted Answer

The greatest pressure drop in the vascular system occurs across the arterioles, not the capillaries. Arterioles, being the primary site of vascular resistance, play a crucial role in regulating blood flow and pressure to various tissues.

Question 16

Arteriolar resistance is regulated by both local controls and extrinsic controls.

Accepted Answer

Arteriolar resistance is regulated by both local controls, such as metabolic factors and myogenic response, and extrinsic controls, such as sympathetic nervous system and hormones.

Question 17

The sphygmomanometer and stethoscope can be used for a direct measurement of arterial blood pressure.

Accepted Answer

The sphygmomanometer and stethoscope are used for an indirect measurement of arterial blood pressure, not a direct measurement. Direct measurement would involve inserting a catheter into an artery.

Question 18

Measurement of arterial pressure using a sphygmomanometer is possible because turbulent blood flow that occurs as arterial pressure overcomes a partially occluded artery, and can be heard by a stethoscope placed just over the artery.

Accepted Answer

This is the standard mechanism by which blood pressure is measured using a sphygmomanometer and stethoscope. The partially occluded artery is created by inflating a cuff around the arm to temporarily stop blood flow, and then slowly releasing the cuff while listening for the sound of turbulent blood flow. The systolic pressure is the pressure at which the first sound (Korotkoff sound) is heard, and the diastolic pressure is the pressure at which the sound disappears.

Question 19

There is a constant flow of blood through the capillaries even though the heart is forcing blood out into the arterial system only part of the time.

Accepted Answer

This is due to the continuous contraction and relaxation of the arterioles, which allow blood to flow through the capillaries even when the heart is not actively pumping. Additionally, the pressure from the venous system also helps maintain a constant flow of blood through the capillaries.

Question 20

The regulation of blood flow in the arterioles of the brain is under the control of mainly the sympathetic nervous system.

Accepted Answer

The regulation of blood flow in the arterioles of the brain is under the control of mainly the local factors such as changes in CO2, O2, and pH levels in the brain tissue. The sympathetic nervous system plays a minor role in this process.

Quiz 9: Vascular Physiology