Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

19. The Blood Vessels

Introduction to Hemodynamics

Anatomy & Physiology

19. The Blood Vessels

Introduction to Hemodynamics

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Problem 4

Textbook Question

Which of the following factors would increase peripheral resistance?
a. Increased blood viscosity
b. Shorter vessel
c. Vasodilation
d. An increase in vessel radius

Verified step by step guidance

Understand the concept of peripheral resistance: Peripheral resistance refers to the resistance to blood flow in the blood vessels, primarily influenced by vessel diameter, blood viscosity, and vessel length.

Analyze the effect of blood viscosity: Increased blood viscosity (thicker blood) leads to greater resistance because thicker blood is harder to move through vessels. This factor increases peripheral resistance.

Evaluate the impact of vessel length: Shorter vessels reduce the distance blood must travel, which decreases resistance. Therefore, shorter vessels do not increase peripheral resistance.

Examine the role of vasodilation: Vasodilation refers to the widening of blood vessels, which decreases resistance by increasing the vessel diameter. This factor reduces peripheral resistance.

Consider the effect of vessel radius: An increase in vessel radius decreases resistance because resistance is inversely proportional to the fourth power of the radius, as described by Poiseuille's law: \( R = \frac{8 \eta L}{\pi r^4} \), where \( R \) is resistance, \( \eta \) is viscosity, \( L \) is vessel length, and \( r \) is radius. Therefore, an increase in vessel radius reduces peripheral resistance.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Peripheral Resistance

Peripheral resistance refers to the resistance to blood flow in the small blood vessels, primarily arterioles. It is a crucial factor in determining blood pressure and is influenced by the diameter of the blood vessels, blood viscosity, and the overall length of the vascular system. Increased peripheral resistance can lead to higher blood pressure and is a key consideration in cardiovascular health.

Blood Viscosity

Blood viscosity is a measure of the thickness and stickiness of blood, which affects how easily it flows through the vessels. Higher viscosity means that the blood is thicker, which increases resistance to flow and can elevate peripheral resistance. Factors such as dehydration or increased red blood cell count can lead to increased blood viscosity.

Vessel Radius

The radius of a blood vessel significantly impacts peripheral resistance, as described by Poiseuille's law. A smaller radius increases resistance, while a larger radius decreases it. Vasodilation (widening of blood vessels) decreases resistance, whereas vasoconstriction (narrowing of blood vessels) increases it, making vessel radius a critical factor in regulating blood flow and pressure.

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Textbook Question

Which of the following conditions would have the greatest effect on peripheral resistance?

(a) Doubling the length of a vessel

(b) Doubling the diameter of a vessel

(d) Doubling the turbulence of the blood

(e) Doubling the number of white cells in the blood

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How do pressure and resistance affect cardiac output and peripheral blood flow?

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Textbook Question

More than one choice may apply.

Using the figure, determine which vessels have the most resistance.

a. Arteries

b. Veins

c. Capillaries

d. Arterioles

e. Venules

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Explain the mechanisms that assist in the return of venous blood to the heart.

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