What is the first step in using an automated external defibrillator (AED) on a patient who has collapsed?

Correct Answer: B

Rationale: The correct answer is B: Turn on the AED and follow the voice prompts. This is the first step in using an AED as the device will guide you through the process of analyzing the heart rhythm and delivering a shock if necessary. Choice A, applying the pads to the chest, comes after turning on the AED. Checking the patient's pulse (Choice C) is not necessary before using an AED as the device is specifically designed to assess the need for defibrillation. Ensuring the area is clear (Choice D) is important for safety but is not the initial step in using an AED.

Correct Answer: A

Rationale: The correct answer is Vitamin A. Vitamin A deficiency leads to night blindness because this vitamin is crucial for the formation of rhodopsin, a photopigment in the retina. Rhodopsin is essential for vision in low-light conditions. Vitamin B12 deficiency can lead to anemia and neurological issues but is not directly related to night blindness. Vitamin C deficiency can cause scurvy, affecting connective tissues, but not night vision. Vitamin D deficiency can lead to bone disorders but is not primarily associated with night blindness.

Correct Answer: A

Rationale: The correct answer is A: Oxygen transport. Hemoglobin in red blood cells binds to oxygen in the lungs and carries it to tissues throughout the body, releasing it where needed. This process is essential for cellular respiration and energy production. Choices B, C, and D are incorrect because hemoglobin's primary function is not related to immunity, blood clotting, or carbon dioxide transport. Hemoglobin's main role is to transport oxygen, ensuring adequate oxygen supply to body tissues for metabolic processes.

Correct Answer: A

Rationale: Multiple sclerosis is the correct answer. It is an autoimmune disease that specifically targets and damages the myelin sheath surrounding neurons in the central nervous system. This demyelination disrupts the transmission of nerve signals and leads to a variety of neurological symptoms. Parkinson's disease (Choice B), Alzheimer's disease (Choice C), and Huntington's disease (Choice D) are neurodegenerative disorders that do not primarily involve demyelination of neurons in the CNS. Parkinson's disease is characterized by the loss of dopamine-producing neurons, Alzheimer's disease by the formation of plaques and tangles in the brain, and Huntington's disease by a genetic mutation affecting nerve cells.