What is the ability of cardiac cells to respond to an impulse by contracting?

Correct Answer: A

Rationale: The correct answer is A: Excitability. Excitability refers to the ability of cardiac cells to respond to an impulse by generating an action potential and contracting. This is the fundamental property that allows the heart to beat. Contractility (B) is the ability of cardiac muscle to contract once stimulated, but it does not specifically refer to the response to an impulse. Rhythmicity (C) is the ability of cardiac cells to generate spontaneous electrical impulses, not directly related to responding to an impulse. Conductivity (D) is the ability of cardiac cells to transmit electrical impulses, not specifically related to the response of cells contracting.

Correct Answer: D

Rationale: Improvement in symptoms is a key indicator of effective anticoagulant therapy.

Correct Answer: A

Rationale: The correct answer is A: Pneumothorax. Pneumothorax is the term used to describe a condition where the lung collapses due to air leaking into the pleural space. This causes pressure on the lung, leading to its collapse. Pleural effusion (B) is the accumulation of fluid in the pleural space, not air. Atelectasis (C) is the collapse of a portion or the entire lung due to various reasons but not air leakage. Pulmonary fibrosis (D) is a condition where lung tissue becomes scarred and thickened, not related to air leakage causing lung collapse.

Correct Answer: A

Rationale: Contractility is the correct answer as it specifically refers to the ability of the heart muscle to contract with a given force without changing its length. This term is used to describe changes in the inotropic state of the muscle, which affects the strength of contraction. Excitability, refractoriness, and automaticity do not directly relate to changes in muscle contraction force without altering fiber length. Excitability is the ability of the muscle to respond to stimuli, refractoriness is the recovery period after a muscle contraction, and automaticity is the ability of certain cells to generate spontaneous electrical activity.

Correct Answer: A

Rationale: The correct answer is A: Platelet count. When administering enoxaparin for DVT prophylaxis, monitoring platelet count is crucial because enoxaparin can cause thrombocytopenia. Decreased platelet count can increase the risk of bleeding. Monitoring PT/INR and aPTT is more relevant for monitoring warfarin or heparin therapy, not enoxaparin. Hemoglobin monitoring is important for assessing anemia but not specifically related to enoxaparin administration for DVT prophylaxis.

Correct Answer: A

Rationale: The correct answer is A: Pneumonia. Pneumonia is an acute respiratory infection that specifically inflames the alveoli in the lungs, leading to fluid or pus accumulation. This condition can affect one or both lungs. Bronchitis (B) is inflammation of the bronchial tubes, not the alveoli. Tuberculosis (C) is a bacterial infection that primarily affects the lungs but does not always involve alveoli inflammation. Asthma (D) is a chronic respiratory condition characterized by airway inflammation and constriction, not alveoli inflammation like in pneumonia.

Correct Answer: A

Rationale: The correct answer is A: Hypertrophic cardiomyopathy. In this condition, the heart muscle becomes thickened, affecting the heart's ability to pump blood efficiently. This is due to genetic mutations causing the muscle cells to grow abnormally. This leads to poor relaxation and filling of the heart, impairing its pumping function. B: Dilated cardiomyopathy involves the heart muscle becoming weak and stretched, leading to reduced pumping ability. C: Restrictive cardiomyopathy involves the heart muscle becoming stiff and rigid, impairing its ability to fill with blood properly. D: Myocarditis is inflammation of the heart muscle, typically caused by infections or autoimmune conditions, leading to temporary reduction in heart function. Hence, the correct answer is A as it specifically describes the scenario of a thickened heart muscle without an obvious cause impacting the heart's pumping ability.

Correct Answer: A

Rationale: The correct answer is A: Mitral regurgitation. When the mitral valve does not close properly, it causes blood to flow backward into the left atrium during the heart's contraction phase. This condition is known as mitral regurgitation. Aortic stenosis (B) is narrowing of the aortic valve, not related to the mitral valve. Tricuspid regurgitation (C) involves the tricuspid valve, not the mitral valve. Pulmonary hypertension (D) is high blood pressure in the lungs, not directly related to a malfunctioning mitral valve.

Correct Answer: A

Rationale: Pulmonary edema is the correct answer because it is characterized by fluid accumulation in the lungs, leading to difficulty in breathing. This condition is often a result of heart failure, where the heart is unable to pump blood effectively, causing fluid to leak into the lungs. It can also be caused by lung infections or exposure to toxins. Pleurisy (B) is inflammation of the pleura, the lining around the lungs, leading to chest pain exacerbated by breathing. Pleural effusion (C) is fluid accumulation in the pleural space around the lungs, not within the lungs themselves. Pneumothorax (D) is characterized by air accumulation in the pleural space, causing lung collapse, but not fluid collection in the lungs.