Correct Answer: A

Rationale: The correct answer is A. Persistent chest pain that may radiate to the arm is a classic symptom of myocardial infarction. This pain is typically described as crushing, pressure-like, or squeezing. Choice B is incorrect because brief sternal chest pain on inspiration is not characteristic of myocardial infarction. Choice C is incorrect because rapid respirations with left-sided weakness and numbness are not typical symptoms of myocardial infarction. Choice D is incorrect because left upper quadrant abdominal pain that radiates to the back and shoulder is not a common presentation of myocardial infarction.

Correct Answer: B

Rationale: Passive immunity is the transfer of pre-formed antibodies from one individual to another, providing immediate but temporary protection. In this case, the correct answer is the transfer of antibodies from the mother to the baby, as it describes the concept of passive immunity. Choice A, vaccination against the disease, refers to active immunity where the individual's immune system is stimulated to produce antibodies. Choice C, cuts or wounds that are infected and heal, is unrelated to immunity. Choice D, having the disease in question, does not describe passive immunity but rather acquiring active immunity through exposure to the pathogen.

Correct Answer: C

Rationale: The correct answer is C: Weakness and confusion. Hypoglycemia is characterized by low blood sugar levels, leading to inadequate glucose supply to the brain, resulting in symptoms like weakness and confusion. Choices A, B, and D are incorrect. Rapid, deep breathing is not typically a sign of hypoglycemia but can be seen in other conditions like respiratory issues. Increased urination is more commonly associated with conditions like diabetes mellitus, while high blood pressure is not a typical sign of hypoglycemia.

Correct Answer: D

Rationale: The sinoatrial node (SA node) in the atrium is indeed responsible for initiating the electrical impulse that starts the heart's rhythm. The SA node is known as the heart's natural pacemaker. Choices A, B, and C are incorrect because while the Purkinje fibers, bundle branches, and atrioventricular node play crucial roles in the conduction of the electrical impulse throughout the heart, the SA node is specifically responsible for initiating this impulse.

Correct Answer: B

Rationale: The correct answer is B: Insufficient circulating blood volume. Hypovolemia is a condition characterized by a decrease in the volume of blood plasma. This reduction in circulating blood volume can lead to inadequate perfusion of tissues and organs, potentially resulting in shock if left untreated. Choices A, C, and D are incorrect because increased urine retention, bounding peripheral pulses, and crackles auscultated in the lungs are not typical manifestations of hypovolemia.