18. The Heart

Cardiac Cycle

Open Question
Discuss how the Frank-Starling law of the heart helps to explain the influence of venous return on stroke volume.
Open Question
Cardiac output is equal to the (a) difference between the end-diastolic volume and the end-systolic volume, (b) product of heart rate and stroke volume, (c) difference between the stroke volume at rest and the stroke volume during exercise, (d) stroke volume less the end-systolic volume, (e) product of heart rate and blood pressure.
Open Question
What three factors regulate stroke volume to ensure that the left and right ventricles pump equal volumes of blood?
Open Question
Identify if the given statement is true or false. Provide a justification if it is false.
tan 72° ≥ cot 27°
Open Question
Differentiate between stroke volume and cardiac output. How is cardiac output calculated?
Open Question
What factors influence cardiac output?
Open Question
The following measurements were made on two individuals (the values recorded remained stable for 1 hour):Person 1: heart rate, 75 bpm; stroke volume, 60 mLPerson 2: heart rate, 90 bpm; stroke volume, 95 mLWhich person has the greater venous return? Which person has the longer ventricular filling time?
Open Question
Karen is taking the medication verapamil, a drug that blocks the calcium channels in cardiac muscle cells. What effect should this medication have on Karen's stroke volume?
Open Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

c. The amount of blood in the ventricles at the end of the ventricular filling phase is the end-systolic volume.
Open Question
Mr. Watson has been diagnosed with mitral insufficiency, or a malfunctioning mitral valve, which causes the valve to not close properly. Predict the signs and symptoms you might expect from a disease of this valve. What would happen to the patient's stroke volume and cardiac output? Explain. What might help improve his cardiac output?
Open Question
Two elements determine blood pressure—the cardiac output of the heart and the peripheral resistance, or friction, in the blood vessels. Name two factors that increase cardiac output. Name two factors that increase peripheral resistance.
Open Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

c. Tissue perfusion to the heart decreases during systole and increases during diastole.