Which of the following components of a neuron is an insulative covering necessary for effective transmission of nerve impulses?
Myelin
Synapse
Axon
Dendrite
The Correct Answer is A
A. Myelin is a fatty substance that wraps around axons in many neurons. It acts as an insulative covering that speeds up the transmission of nerve impulses by enabling the signal to jump between gaps in the myelin (called nodes of Ranvier). This is the correct answer.
B. The synapse is the junction between two neurons where signals are transmitted. It is not involved in the insulative covering of a neuron.
C. The axon is the long, slender part of a neuron that transmits electrical signals, but it requires myelin to efficiently conduct those signals.
D. Dendrites are branched extensions of a neuron that receive signals from other neurons. They do not have an insulative function.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. The diaphysis is the shaft of a long bone, the central part that extends between the two epiphyses (ends). It is primarily composed of compact bone and houses the bone marrow.
B. The periosteum is a dense layer of connective tissue that covers the outer surface of bones, except at the joints. It does not represent the shaft of the bone.
C. The cortex refers to the outer layer of the bone, specifically the compact bone that surrounds the spongy bone in the diaphysis. It is not synonymous with the shaft.
D. Osteoid is the organic matrix of bone tissue, composed of collagen and other proteins, but it does not refer to the shaft of a bone.
Correct Answer is B
Explanation
A. The pulmonic valve separates the right ventricle from the pulmonary artery, controlling blood flow to the lungs, not the right atrium from the right ventricle.
B. The tricuspid valve separates the right atrium from the right ventricle, allowing blood to flow from the atrium into the ventricle before it is pumped to the lungs.
C. The aortic valve separates the left ventricle from the aorta, controlling blood flow from the heart to the body, not between the atrium and ventricle.
D. The mitral valve separates the left atrium from the left ventricle, controlling blood flow in the left side of the heart.
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