Human Physiology Week 5 - Cardiovascular (Transcripts 2)

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Questions and Answers

What is the effect of vasoconstriction on the lumen of a blood vessel?

It decreases the lumen size. (correct)

It causes the vessel to expand.

It has no effect on the lumen size.

It increases the lumen size.

In the context of blood flow, what happens when the lumen of a blood vessel is reduced?

Vascular resistance decreases.

Blood flow remains unchanged.

Blood flow increases significantly.

Vascular resistance increases. (correct)

What is the role of smooth muscle in blood vessels during vasoconstriction?

It becomes inactive during vasoconstriction.

It relaxes to allow more blood flow.

It dilates the blood vessel.

It contracts to reduce the diameter of the vessel. (correct)

Which side of the blood vessel is referred to as the proximal side?

The side where blood is entering. Signup and view all the answers

What happens in the area of a blood vessel undergoing vasoconstriction compared to an area with no change?

The area undergoing vasoconstriction has increased vascular resistance. Signup and view all the answers

What occurs to blood pressure proximal to the site of increased resistance caused by vasoconstriction?

It increases. Signup and view all the answers

What is the effect of vasoconstriction on blood vessel lumen?

It creates a bottleneck. Signup and view all the answers

In which scenario does total peripheral resistance increase?

When multiple areas of the body experience vasoconstriction. Signup and view all the answers

What is the primary consequence of increased resistance in blood vessels?

Increased hydrostatic pressure. Signup and view all the answers

What happens to blood flow when there is a bottleneck in the vessel due to vasoconstriction?

Blood flow may back up behind the bottleneck. Signup and view all the answers

What percentage of blood flow typically goes to the kidneys and GI tract at rest?

40 to 50% Signup and view all the answers

What describes the condition when multiple arteries simultaneously constrict?

Total peripheral resistance increase. Signup and view all the answers

How does vasoconstriction affect smooth muscle in blood vessels?

It triggers muscles to contract. Signup and view all the answers

What happens to blood pressure when it encounters resistance in the vasculature?

Blood pressure increases proximal to the resistance. Signup and view all the answers

How does total peripheral resistance influence systemic arterial blood pressure?

It increases systemic arterial blood pressure by creating blood backups. Signup and view all the answers

What role do atherosclerotic plaques play in vascular resistance?

They increase vascular resistance by narrowing the lumen. Signup and view all the answers

What is the consequence of smooth muscle hypertrophy in blood vessels?

It results in inward remodeling and a reduction in lumen size. Signup and view all the answers

How does hematocrit affect total peripheral resistance?

Higher hematocrit can increase resistance due to increased blood viscosity. Signup and view all the answers

What is a result of vasoconstriction in blood vessels supplying the kidneys?

Increased blood pressure proximal to the vasoconstriction. Signup and view all the answers

What effect does backward blood flow due to increased resistance have on the aorta?

It leads to increased aortic pressure. Signup and view all the answers

Study Notes

Vasoconstriction and Vascular Resistance

Vasoconstriction, the narrowing of blood vessels, increases vascular resistance, making it harder for blood to flow through.
The narrowing caused by vasoconstriction creates a bottleneck, increasing pressure proximal to the constriction.
The pressure increase occurs due to blood accumulating and backing up before the narrowed area.

Total Peripheral Resistance (TPR)

TPR reflects the overall resistance to blood flow throughout the circulatory system.
Vasoconstriction in multiple organs, like kidneys, gastrointestinal tract, and skin, simultaneously increases TPR.
Increased TPR leads to a buildup of blood pressure in the aorta, ultimately increasing systemic arterial blood pressure.

Factors Influencing TPR

Atherosclerotic plaques: Damage to endothelial cells and plaque formation within blood vessels increase resistance to blood flow, contributing to higher TPR.
Inward remodeling: Smooth muscle hypertrophy in arteries can permanently reduce the lumen size, increasing resistance even in a relaxed state.
Elevated hematocrit: An increased percentage of red blood cells in the blood makes the blood thicker (more viscous), causing greater friction and resistance to flow, leading to higher TPR.

### Sympathetic Nervous System's Role in TPR

The sympathetic nervous system plays a significant role in regulating TPR.
It causes vasoconstriction of arteries and arterioles through adrenergic receptors.
This vasoconstriction ultimately increases TPR and blood pressure.

Sympathetic Nervous System & Total Peripheral Resistance

The sympathetic nervous system causes vasoconstriction of arteries and arterioles.
Vasoconstriction increases total peripheral resistance (TPR).
Increased TPR leads to increased systemic arterial blood pressure.

Factors Affecting TPR

Atherosclerosis (plaques in blood vessels) increases TPR.
Artery/arterial remodeling (inward remodeling) increases TPR.
Increased hematocrit (proportion of red blood cells in blood) increases TPR.

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Description

Test your knowledge on the effects of vasoconstriction and vascular resistance. This quiz covers concepts such as total peripheral resistance, the impact of atherosclerotic plaques, and factors influencing blood flow. Enhance your understanding of cardiovascular physiology with this engaging quiz.