Biology Chapter 19 Review Questions

Questions and Answers

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.

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?

The right atrium receives blood from the systemic circuit.

Distinguish among efferent vessels, afferent vessels, and exchange vessels.

Efferent vessels (arteries) carry blood away from the heart, afferent vessels (veins) carry blood to the heart, and exchange vessels (capillaries) exchange nutrients, dissolved gases, and wastes between the blood and interstitial fluid. Signup and view all the answers

List the five general classes of blood vessels.

The five general classes of blood vessels are arteries, arterioles, capillaries, venules, and veins. Signup and view all the answers

Describe a capillary.

A capillary is a small blood vessel, located between an arteriole and a venule, whose thin wall permits exchange between blood and interstitial fluid by diffusion. Signup and view all the answers

Identify the two types of capillaries with a complete endothelium.

The two types of capillaries with a complete endothelium are continuous capillaries and fenestrated capillaries. Signup and view all the answers

At what sites in the body are fenestrated capillaries located?

Fenestrated capillaries are located in endocrine glands, choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys. Signup and view all the answers

Why are valves located in veins but not in arteries?

Valves in veins prevent blood from flowing backward whenever the venous pressure drops. In the arterial system, pressures are high enough to keep the blood moving away from the heart. Signup and view all the answers

How is blood pressure maintained in veins to counter the force of gravity?

Blood pressure in veins is maintained by valves, which prevent backflow, and the contraction of surrounding skeletal muscles that squeezes venous blood toward the heart. Signup and view all the answers

Describe the distribution of total blood volume in the body.

The systemic venous system contains 64%, the systemic arterial system contains 13%, and the remainder is contained in the heart (7%), pulmonary circulations (9%), and systemic capillaries (7%). Signup and view all the answers

What factors are involved in the formation of varicose veins?

Varicose veins result from the pooling of blood due to gravity and the failure of venous valves. Signup and view all the answers

Neural and endocrine regulatory mechanisms influence which factors?

They influence heart rate, stroke volume, peripheral resistance, and venous pressure. Signup and view all the answers

Arterial pressure is higher than venous pressure.

True Signup and view all the answers

Why is it beneficial for capillary pressure to be very low?

Very low capillary pressure allows time for diffusion between the blood and the surrounding interstitial fluid. Signup and view all the answers

List the factors that contribute to total peripheral resistance.

Total peripheral resistance reflects a combination of vascular resistance, vessel length, vessel luminal diameter, blood viscosity, and turbulence. Signup and view all the answers

Explain the equation R ∝ 1/r^4.

The equation states that resistance (R) is inversely proportional to the fourth power of the vessel radius (r). Signup and view all the answers

An increase in vessel diameter reduces peripheral resistance.

True Signup and view all the answers

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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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!