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Questions and Answers
Describe the pulmonary circuit.
Describe the pulmonary circuit.
The pulmonary circuit transports blood from the right ventricle through the pulmonary arteries, capillaries in the lungs, and pulmonary veins and returns it to the left atrium.
Describe the systemic circuit.
Describe the systemic circuit.
The systemic circuit transports blood through the arteries, capillaries, and veins of the body from the left ventricle to the right atrium. Blood returning to the heart from the systemic circuit must complete the pulmonary circuit before it re-enters the systemic circuit.
Which chamber of the heart receives blood from the systemic circuit?
Which chamber of the heart receives blood from the systemic circuit?
The right atrium receives blood from the systemic circuit.
Distinguish among efferent vessels, afferent vessels, and exchange vessels.
Distinguish among efferent vessels, afferent vessels, and exchange vessels.
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List the five general classes of blood vessels.
List the five general classes of blood vessels.
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Describe a capillary.
Describe a capillary.
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Identify the two types of capillaries with a complete endothelium.
Identify the two types of capillaries with a complete endothelium.
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At what sites in the body are fenestrated capillaries located?
At what sites in the body are fenestrated capillaries located?
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Why are valves located in veins but not in arteries?
Why are valves located in veins but not in arteries?
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How is blood pressure maintained in veins to counter the force of gravity?
How is blood pressure maintained in veins to counter the force of gravity?
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Describe the distribution of total blood volume in the body.
Describe the distribution of total blood volume in the body.
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What factors are involved in the formation of varicose veins?
What factors are involved in the formation of varicose veins?
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Neural and endocrine regulatory mechanisms influence which factors?
Neural and endocrine regulatory mechanisms influence which factors?
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Arterial pressure is higher than venous pressure.
Arterial pressure is higher than venous pressure.
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Why is it beneficial for capillary pressure to be very low?
Why is it beneficial for capillary pressure to be very low?
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List the factors that contribute to total peripheral resistance.
List the factors that contribute to total peripheral resistance.
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Explain the equation R ∝ 1/r^4.
Explain the equation R ∝ 1/r^4.
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An increase in vessel diameter reduces peripheral resistance.
An increase in vessel diameter reduces peripheral resistance.
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Study Notes
Pulmonary and Systemic Circuits
- The pulmonary circuit carries blood from the right ventricle through pulmonary arteries to the lungs and back to the left atrium via pulmonary veins.
- The systemic circuit transports blood from the left ventricle to the body and returns it to the right atrium, requiring the blood to pass through the pulmonary circuit first for re-oxygenation.
Heart Chambers
- Blood from the systemic circuit is received by the right atrium.
Blood Vessels
- Efferent vessels (arteries) move blood away from the heart, while afferent vessels (veins) bring blood to the heart.
- Exchange of nutrients, gases, and wastes occurs in capillaries, which are the exchange vessels.
Types of Blood Vessels
- Five general classes of blood vessels include arteries, arterioles, capillaries, venules, and veins.
Capillaries
- Capillaries are small vessels connecting arterioles to venules, featuring thin walls that allow diffusion of substances between blood and interstitial fluid.
- Continuous and fenestrated capillaries both have complete endothelium.
- Fenestrated capillaries are found in areas such as endocrine glands, choroid plexus, intestinal absorptive regions, and kidney filtration sites.
Venous System
- Valves are present in veins to prevent backflow due to low pressure; arteries do not require valves because of high pressure.
- Venous blood flow is maintained against gravity by skeletal muscle contractions and valve presence.
Blood Volume Distribution
- Total blood volume is distributed as follows: systemic venous system (64%), systemic arterial system (13%), heart (7%), pulmonary circulation (9%), and systemic capillaries (7%).
Varicose Veins
- Varicose veins are swollen, sagging veins caused by blood pooling due to gravity and valve failure.
Regulatory Mechanisms
- Neural and endocrine mechanisms impact heart rate, stroke volume, peripheral resistance, and venous pressure.
Blood Pressure
- Arterial pressure is significantly greater than venous pressure due to the need to push blood through various vessels.
Capillary Pressure
- Low capillary pressure facilitates adequate time for substance diffusion between blood and interstitial fluid.
Peripheral Resistance
- Total peripheral resistance is influenced by vascular resistance, vessel length, luminal diameter, blood viscosity, and turbulence.
- Resistance is described by the equation R ∝ 1/r^4, illustrating that resistance decreases significantly with small increases in vessel diameter.
Peripheral Resistance Factors
- Increasing vessel diameter reduces peripheral resistance, whereas increasing vessel length raises it.
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Description
Test your understanding of the pulmonary and systemic circuits with these flashcards. This quiz covers the key functions and pathways of blood circulation in the body. Get ready to reinforce your knowledge of cardiovascular physiology!
