Always draw up the regular insulin into the syringe first.

Choice A rationale

Sumatriptan does not cause vasodilation of peripheral blood vessels. Instead, it has vasoconstrictive properties.

Choice B rationale

Sumatriptan does not depress pain response in the central nervous system. Its primary action is on the cranial blood vessels.

Choice C rationale

Sumatriptan is a selective serotonin receptor agonist that causes vasoconstriction of cranial blood vessels, relieving migraine headaches.

Choice D rationale

Sumatriptan does not bind to acetylcholine receptors or prevent nerve transmission. It specifically targets serotonin receptors in cranial blood vessels.

Choice A rationale

This choice is incorrect. A complete occlusion of a coronary vessel results in a myocardial infarction (heart attack), not unstable angina. Unstable angina occurs when there is a significant narrowing or partial blockage of a coronary artery, leading to reduced blood flow and oxygen supply to the heart muscle, causing pain or discomfort. Complete occlusion would cause permanent damage to the heart muscle, which is not the case with unstable angina.

Choice B rationale

This choice is correct. While unstable angina is mainly caused by narrowing of the coronary arteries, it can also be caused by a spasm of the blood vessel. This spasm, also known as vasospasm, reduces the amount of blood flow to the heart muscle, resulting in pain. These spasms can occur even if the coronary arteries do not have significant plaque buildup, adding another layer of complexity to the condition.

Choice C rationale

This choice is partially correct. The body’s response to a lack of oxygen (ischemia) in the heart muscle does result in pain, known as angina. However, this choice does not fully capture the specific nature of unstable angina, which involves episodes of pain that occur more frequently and are more severe than those associated with stable angina, and can occur at rest or with minimal exertion, indicating a higher risk for a heart attack.

Choice D rationale

This choice is correct. Unstable angina is characterized by a serious narrowing of a coronary artery that reduces oxygen supply to the heart. This narrowing is typically due to atherosclerotic plaque and can be complicated by blood clots or spasms. Unlike stable angina, the pain of unstable angina is more unpredictable and can occur without a triggering factor like exercise or stress, signaling a higher risk of a heart attack.