AP Biology : Understanding Other Cardiac Physiology

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #142 : Systems Physiology

After deoxygenated blood enters the heart at the right atrium, what path does it take?

Possible Answers:

It follows the pulmonary circuit

It follows the systemic circuit

It travels through the right side of the heart, flows to the left side of the heart, and then enters the lungs before returning to the body

It exits the heart through the pulmonary veins, then returns through the pulmonary arteries

Correct answer:

It follows the pulmonary circuit

Explanation:

The circulatory system is composed of two primary regions: the systemic circuit and the pulmonary circuit.

The systemic circuit allows blood to travel from the heart to the tissues of the body, delivering nutrients and oxygen, and then returns the deoxygenated blood to the heart. Most arteries, arterioles, capillaries, venules, and veins are part of the systemic circuit. The systemic circuit essentially starts with the aorta and ends with the vena cavae.

The pulmonary circuit receives dexoygenated blood from the body and carries it to the lungs for reoxygentation, before returning it to the heart to enter the systemic circuit through the aorta.

In general circulation, the vena cavae empty into the right atrium. Blood then enters the right ventricle and enters the pulmonary circuit. It travels to the lungs through the pulmonary arteries, becomes reoxygenated in the capillaries of the lungs, then returns to the left atrium via the pulmonary veins. From the left atrium, blood enters the left ventricle and is transferred to the systemic circuit.

Example Question #143 : Systems Physiology

Output from the heart can be altered mainly by changing which two variables?

Possible Answers:

Stroke volume and heart rate

Breathing rate and stroke volume

Blood pressure and heart rate

Stroke volume and blood pressure

Correct answer:

Stroke volume and heart rate

Explanation:

Multiplying stroke volume by heart rate gives another measure called cardiac output. Stroke volume will be influenced by variables such as resistance in the arteries and contractility of the heart muscle cells, while heart rate will be influenced by variables such as emotional state and age. Both stroke volume and heart rate increase with exercise.

 

Example Question #144 : Systems Physiology

Which portion of the heart would you expect to be the largest in a person with systemic high blood pressure?

Possible Answers:

Right ventricle

Left atrium

Right atrium

Left ventricle

Correct answer:

Left ventricle

Explanation:

The left ventricle supplies oxygenated blood from the heart to the aorta so it can be distributed to the body. The left ventricle must overcome the forces in the aorta and arteries (e.g., blood pressure). The higher the blood pressure, the harder the left ventricle must contract to force blood out of the aortic valve. This leads to muscle growth and enlargement of the left ventricle over time.

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