Which of the following is a central vasodilator and peripheral vasoconstrictor?

Correct Answer: A

Rationale: The correct answer is A: Sympathetic nervous system. The sympathetic nervous system releases norepinephrine, which acts as a central vasodilator by dilating blood vessels in the heart and skeletal muscles. It also acts as a peripheral vasoconstrictor by constricting blood vessels in other areas to redirect blood flow to vital organs during fight-or-flight responses. B: Parasympathetic nervous system is incorrect as it primarily promotes rest and digestion, not vasodilation or vasoconstriction. C: Norepinephrine is incorrect as it acts as a peripheral vasoconstrictor, not a central vasodilator. D: Acetylcholine is incorrect as it primarily functions in the parasympathetic nervous system and is not associated with central vasodilation or peripheral vasoconstriction.

Correct Answer: A

Rationale: The correct answer is A: Cardiac output. Cardiac output is the total amount of blood pumped by the heart in a minute. It is calculated by multiplying the heart rate (beats per minute) by the stroke volume (amount of blood pumped per beat). This measurement gives an indication of how effectively the heart is functioning in delivering oxygenated blood to the body. B: Stroke volume is the amount of blood pumped by the heart in each beat, not the total amount in a minute. C: End-diastolic volume is the amount of blood in the ventricles before contraction, not the total amount pumped in a minute. D: Ejection fraction is the percentage of blood pumped out of the ventricles with each contraction, not the total amount in a minute.

Correct Answer: A

Rationale: The correct answer is A: Cardiac arrest. Cardiac arrest is a life-threatening emergency where the heart stops beating suddenly. This leads to the cessation of blood flow to vital organs, causing loss of consciousness and death if not treated immediately with CPR and defibrillation. Myocardial infarction (B) is a heart attack where blood flow to the heart muscle is blocked, leading to tissue damage. Heart failure (C) is a chronic condition where the heart is unable to pump blood effectively. Atrial fibrillation (D) is an irregular heartbeat that can increase the risk of stroke but is not the same as cardiac arrest.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Hypertrophic cardiomyopathy (A) is the correct answer. 2. In this condition, the heart muscle thickens, leading to decreased blood pumping ability. 3. This thickening can obstruct blood flow and increase the risk of abnormal heart rhythms. 4. Dilated cardiomyopathy (B) involves the heart enlarging and weakening, not thickening. 5. Restrictive cardiomyopathy (C) involves stiffening of the heart muscle, not thickening. 6. Ischemic cardiomyopathy (D) results from reduced blood flow to the heart, not thickening.

Correct Answer: A

Rationale: The correct answer is A: Bronchoscopy. Bronchoscopy is a procedure where a thin, flexible tube with a camera is inserted into the airways to visualize and diagnose lung diseases directly. It allows for direct visualization of the airways, collection of samples for biopsy, and removal of obstructions. Thoracentesis (B) is a procedure to remove fluid from the pleural space, not for visualizing airways. Pulmonary function test (C) measures lung function but doesn't directly visualize airways. Chest X-ray (D) provides an image of the lungs but doesn't allow for direct visualization or diagnosis of airway diseases.