AP Biology : Understanding Other Cardiac Physiology
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Example Question #51 : Circulatory System
After deoxygenated blood enters the heart at the right atrium, what path does it take?
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 follows the pulmonary circuit
It exits the heart through the pulmonary veins, then returns through the pulmonary arteries
It follows the systemic circuit
It follows the pulmonary circuit
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 #1 : Understanding Other Cardiac Physiology
Output from the heart can be altered mainly by changing which two variables?
Blood pressure and heart rate
Stroke volume and blood pressure
Stroke volume and heart rate
Breathing rate and stroke volume
Stroke volume and heart rate
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 #5 : Cardiac Physiology
Which portion of the heart would you expect to be the largest in a person with systemic high blood pressure?
Right atrium
Left ventricle
Right ventricle
Left atrium
Left ventricle
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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