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What is the term for the amount of blood ejected by the left ventricle into the aorta per beat, determined by preload, contractility, and afterload?
- A. Stroke volume
- B. Cardiac output
- C. End-diastolic volume
- D. Ejection fraction
Correct Answer: A
Rationale: The correct answer is A: Stroke volume. Stroke volume is the amount of blood ejected by the left ventricle into the aorta per beat. Preload (end-diastolic volume), contractility, and afterload influence stroke volume. Cardiac output (B) is the total volume of blood pumped by the heart per minute. End-diastolic volume (C) is the volume of blood in the ventricle before contraction. Ejection fraction (D) is the percentage of blood ejected from the ventricle during systole.
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Which neurotransmitter is released by the sympathetic nervous system (SNS) to increase heart rate and the force of contraction of the heart?
- A. Norepinephrine
- B. Epinephrine
- C. Dopamine
- D. Acetylcholine
Correct Answer: A
Rationale: The correct answer is A: Norepinephrine. Norepinephrine is released by the sympathetic nervous system (SNS) to increase heart rate and the force of contraction. This neurotransmitter acts on beta-1 adrenergic receptors in the heart, leading to these effects. Epinephrine (choice B) is also released by the SNS and acts similarly to norepinephrine but is not as specific for the heart's beta-1 receptors. Dopamine (choice C) primarily acts as a precursor to norepinephrine and epinephrine and does not directly increase heart rate or force of contraction. Acetylcholine (choice D) is released by the parasympathetic nervous system and decreases heart rate and the force of contraction.
What is a condition where the blood supply to the brain is interrupted or reduced, preventing brain tissue from getting oxygen and nutrients?
- A. Stroke
- B. Transient ischemic attack (TIA)
- C. Myocardial infarction
- D. Angina
Correct Answer: A
Rationale: The correct answer is A: Stroke. A stroke occurs when the blood supply to the brain is interrupted or reduced, leading to a lack of oxygen and nutrients to brain tissue. This can result in brain cell damage or death. A transient ischemic attack (TIA) is a temporary interruption of blood flow to the brain with similar symptoms but resolves quickly without causing permanent damage. Myocardial infarction is a heart attack caused by blockage of blood flow to the heart muscle, not the brain. Angina is chest pain due to reduced blood flow to the heart, not the brain. Thus, only a stroke directly involves the interruption of blood supply to the brain, making it the correct answer.
A patient with chronic heart failure is treated with hydrochlorothiazide, digoxin, and lisinopril. To prevent the risk of digitalis toxicity with these drugs, it is most important that the nurse monitor the patient's
- A. HR
- B. BP
- C. Potassium levels
- D. GI function
Correct Answer: C
Rationale: Hypokalemia is one of the most common causes of digitalis toxicity. When a patient is receiving potassium losing diuretics, such as hydrochlorothiazide and furosemide, it is essential to monitor the potassium level.
What is a condition where the heart's ability to pump blood is decreased, leading to fluid buildup in the lungs and other parts of the body?
- A. Heart failure
- B. Cardiomyopathy
- C. Pericarditis
- D. Myocarditis
Correct Answer: A
Rationale: The correct answer is A: Heart failure. Heart failure occurs when the heart's ability to pump blood is reduced, causing fluid buildup in the lungs and other body parts due to inadequate circulation. It is a condition characterized by the heart's inability to meet the body's demands. Cardiomyopathy (B) is a disease of the heart muscle, while pericarditis (C) is inflammation of the pericardium, and myocarditis (D) is inflammation of the heart muscle. These conditions can lead to heart failure but are not the direct cause of decreased pumping ability.
What is a type of heart disease that involves the thickening or stiffening of the heart muscle, reducing its ability to pump blood?
- A. Hypertrophic cardiomyopathy
- B. Dilated cardiomyopathy
- C. Restrictive cardiomyopathy
- D. Arrhythmia
Correct Answer: A
Rationale: The correct answer is A: Hypertrophic cardiomyopathy. This condition involves the thickening of the heart muscle, leading to reduced blood pumping ability. This thickening makes it harder for the heart to relax and fill with blood properly, impairing its ability to pump effectively. Dilated cardiomyopathy (B) involves the enlargement of the heart chambers, not thickening. Restrictive cardiomyopathy (C) involves stiffening but not necessarily thickening of the heart muscle. Arrhythmia (D) refers to irregular heart rhythms and does not relate to the structural changes in the heart muscle seen in hypertrophic cardiomyopathy.