What is ejection fraction?
Percentage of blood that leaves the heart in a minute
Percentage of blood that leaves the heart with each beat
Amount of blood that leaves the heart with each beat
Amount of blood that leaves the heart in a minute
The Correct Answer is B
Choice A reason: This is not the definition of ejection fraction. The percentage of blood that leaves the heart in a minute is related to the cardiac output, which is the product of the heart rate and the stroke volume.
Choice B reason: This is the correct definition of ejection fraction. It is the ratio of the stroke volume (the amount of blood pumped by the left ventricle) to the end-diastolic volume (the amount of blood in the left ventricle at the end of diastole). It is a measure of the efficiency of the heart and reflects the contractility of the cardiac muscle.
Choice C reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart with each beat is the stroke volume, which is one of the factors that determine the ejection fraction.
Choice D reason: This is not the definition of ejection fraction. The amount of blood that leaves the heart in a minute is the cardiac output, which is influenced by the ejection fraction, but not equivalent to it.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A reason: Hereditary decrease in IgE responsiveness is not related to airway hyper-responsiveness in extrinsic asthma. IgE is an antibody that binds to allergens and triggers the release of histamine and other inflammatory mediators from mast cells. A decrease in IgE responsiveness would reduce the allergic reaction, not increase it.
Choice B reason: Increased sympathetic nervous system response is not related to airway hyper-responsiveness in extrinsic asthma. The sympathetic nervous system is the part of the autonomic nervous system that prepares the body for fight or flight. It stimulates the bronchodilation, or the widening of the airways, by activating the beta2 receptors on the smooth muscle cells. This would improve the airflow, not obstruct it.
Choice C reason: The release of stress hormones is not related to airway hyper-responsiveness in extrinsic asthma. Stress hormones, such as cortisol and adrenaline, are secreted by the adrenal glands in response to stress. They have anti-inflammatory and bronchodilator effects, which would reduce the symptoms of asthma, not worsen them.
Choice D reason: Exposure to an allergen causing mast cell degranulation is related to airway hyper-responsiveness in extrinsic asthma. Mast cell degranulation is the process of releasing histamine and other inflammatory mediators from the granules inside the mast cells. These substances cause bronchoconstriction, or the narrowing of the airways, by stimulating the smooth muscle contraction and mucus secretion. This leads to the symptoms of asthma, such as wheezing, coughing, and dyspnea.
Correct Answer is C
Explanation
Choice A reason: This is not a symptom of right heart failure. Hypertension is a risk factor for developing heart failure, but it does not indicate the severity or location of the heart failure.
Choice B reason: This is not a symptom of right heart failure. Dyspnea upon exertion is a symptom of left heart failure, which occurs when the left ventricle fails to pump blood effectively to the lungs.
Choice C reason: This is a symptom of right heart failure. Significant edema to both lower legs and feet is a result of increased pressure in the systemic circulation, which occurs when the right ventricle fails to pump blood effectively to the rest of the body. This causes fluid to accumulate in the dependent areas, such as the lower extremities.
Choice D reason: This is not a symptom of right heart failure. Decreased urine output is a symptom of left heart failure, which occurs when the left ventricle fails to pump blood effectively to the aorta and the rest of the body. This causes reduced renal perfusion and oliguria.
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