Nursing Elites

1. Which valve prevents backflow into the atrium when the ventricles contract?

• A. Pulmonary valve
• B. Tricuspid valve
• C. Mitral valve
• D. Aortic valve

Correct answer: B

Rationale: The tricuspid valve (right atrioventricular valve) prevents backflow into the right atrium when the right ventricle contracts. This valve ensures that blood flows in the correct direction, preventing regurgitation into the atrium. The pulmonary valve is responsible for preventing backflow into the right ventricle from the pulmonary artery. The mitral valve prevents backflow into the left atrium, and the aortic valve prevents backflow into the left ventricle from the aorta. Therefore, the correct answer is the tricuspid valve as it specifically addresses the scenario of backflow into the atrium during ventricular contraction.

2. Which structure contains the genetic material (DNA) of the cell?

• A. Cytoplasm
• B. Nucleus
• C. Cell wall (only present in plant cells)
• D. Golgi apparatus

Correct answer: B

Rationale: The nucleus is the organelle that contains the genetic material (DNA) of the cell. It acts as the control center of the cell, regulating gene expression and coordinating cellular activities. The cytoplasm is the fluid-filled space within the cell where organelles are suspended, but it does not contain the genetic material. The cell wall is a rigid structure found in plant cells that provides support and protection, but it does not house the DNA. The Golgi apparatus is involved in processing and packaging proteins for secretion, but it does not contain the genetic material of the cell.

3. What is the main consequence of a malfunctioning thyroid gland that produces abnormally low levels of thyroid hormones?

• A. Increased energy levels and weight loss
• B. Decreased heart rate and body temperature
• C. Enhanced muscle growth and bone development
• D. Faster metabolism and heightened alertness

Correct answer: B

Rationale: The correct answer is B: Decreased heart rate and body temperature. A malfunctioning thyroid gland that produces abnormally low levels of thyroid hormones leads to hypothyroidism, resulting in decreased metabolic activity. This reduction in metabolic rate can cause a decreased heart rate and lower body temperature. Choices A, C, and D are incorrect because hypothyroidism typically manifests as symptoms such as fatigue, weight gain, cold intolerance, bradycardia, and decreased body temperature, rather than increased energy levels, enhanced muscle growth, faster metabolism, or heightened alertness.

4. How does sunscreen protect the skin from harmful ultraviolet (UV) rays?

• A. By reflecting UV rays away from the skin
• B. By absorbing UV rays and converting them to heat
• C. By blocking UV rays completely
• D. By stimulating melanin production

Correct answer: B

Rationale: Sunscreen works by absorbing UV rays and converting them to heat. This mechanism helps to prevent the UV rays from penetrating the skin and causing damage such as sunburn, premature aging, and skin cancer. Reflecting UV rays away from the skin (option A) is not the primary function of sunscreen. While sunscreen does block UV rays, it does not do so completely (option C) as some UV rays may still penetrate the skin. Sunscreen does not stimulate melanin production (option D) as a means of protecting the skin from UV rays.

5. Neurotransmitters send chemical messages across the gap between one neuron and another through which of the following structures?

• A. Schwann cell
• B. ganglion
• C. synapse
• D. axon

Correct answer: C

Rationale: Neurotransmitters send chemical messages across the gap between one neuron and another through a structure called the synapse. The synapse is a specialized junction where the axon of one neuron meets the dendrite or cell body of another neuron. Neurotransmitters are released from the axon terminal of the presynaptic neuron and travel across the synaptic cleft to bind to receptors on the postsynaptic neuron, transmitting the signal between the two neurons. Choice A, Schwann cell, is incorrect as Schwann cells are responsible for producing myelin sheath around axons in the peripheral nervous system, not for transmitting neurotransmitters between neurons. Choice B, ganglion, is incorrect as ganglia are clusters of nerve cell bodies outside the central nervous system and do not directly participate in the transmission of chemical messages between neurons. Choice D, axon, is incorrect as the axon is a long, slender projection of a neuron that conducts electrical impulses away from the cell body and towards the axon terminals, where neurotransmitters are released into the synapse, but it is not the structure across which neurotransmitters travel to communicate between neurons.

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