Nursing Elites

1. Which cells myelinate neurons in the PNS?

• A. Oligodendrocytes
• B. Astrocytes
• C. Schwann cells
• D. Microglia

Correct answer: C

Rationale: Schwann cells are the glial cells responsible for myelinating neurons in the peripheral nervous system (PNS). They form the myelin sheath around axons, which helps in the conduction of electrical impulses. Oligodendrocytes, on the other hand, myelinate neurons in the central nervous system (CNS). Astrocytes primarily provide support for neuronal function by regulating the chemical environment around neurons and maintaining the blood-brain barrier. Microglia are part of the immune response in the CNS, where they act as the resident macrophages, playing a role in immune surveillance and response to injury or disease. Therefore, the correct answer is Schwann cells (Choice C) as they specifically myelinate neurons in the PNS, differentiating them from the other cell types mentioned in the choices.

2. What is the primary function of the myelin sheath that surrounds some axons in the nervous system?

• A. To initiate nerve impulses
• B. To transmit sensory information
• C. To speed up the transmission of nerve impulses
• D. To connect neurons at synapses

Correct answer: C

Rationale: The primary function of the myelin sheath is to speed up the transmission of nerve impulses. The myelin sheath acts as an insulating layer around the axon, allowing for faster conduction of electrical impulses along the nerve fiber. This insulation prevents the electrical signal from dissipating or 'leaking' out, which helps in the rapid and efficient transmission of nerve impulses along the axon. Choice A is incorrect because the myelin sheath does not initiate nerve impulses; it helps in conducting them. Choice B is incorrect as the myelin sheath's main role is not in transmitting sensory information but rather in facilitating the transmission of nerve impulses. Choice D is incorrect because the myelin sheath's function is not to connect neurons at synapses; instead, it is primarily involved in enhancing the speed of nerve impulse transmission.

3. Which muscular tube carries urine from the kidneys to the bladder?

• A. Nephron
• B. Ureter
• C. Urethra
• D. Glomerulus

Correct answer: B

Rationale: The correct answer is B: Ureter. The ureter is the muscular tube that carries urine from the kidneys to the bladder. The nephron is the functional unit of the kidney responsible for filtering blood and producing urine. The urethra is the tube that carries urine from the bladder out of the body. The glomerulus is a network of capillaries in the nephron where filtration of blood occurs.

4. Which type of nutrients require minimal digestion before absorption?

• A. Carbohydrates
• B. Proteins
• C. Fats
• D. Vitamins

Correct answer: D

Rationale: A) Carbohydrates: Carbohydrates require digestion by enzymes in the mouth, stomach, and small intestine before they can be broken down into simple sugars for absorption. B) Proteins: Proteins need to be broken down into amino acids by stomach acid and digestive enzymes in the stomach and small intestine before they can be absorbed. C) Fats: Fats require bile from the gallbladder to emulsify them into smaller droplets for enzymes to break them down into fatty acids and glycerol for absorption. D) Vitamins: Vitamins are organic compounds that are already in a form that can be readily absorbed by the body without extensive digestion. They are absorbed directly into the bloodstream from the small intestine and do not require significant breakdown before absorption.

5. What is the function of the lymphatic system?

• A. To transport oxygen
• B. To filter waste from the blood
• C. To produce red blood cells
• D. To regulate body temperature

Correct answer: B

Rationale: The correct answer is B: 'To filter waste from the blood.' The lymphatic system is responsible for draining excess fluid from tissues, absorbing fats from the digestive system, and filtering out harmful substances and waste products from the blood. It also plays a crucial role in the body's immune defense by transporting white blood cells and antibodies to fight off infections. Choices A, C, and D are incorrect because transporting oxygen, producing red blood cells, and regulating body temperature are functions performed by other systems in the body, such as the respiratory system, bone marrow, and thermoregulatory mechanisms, respectively.

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