Which of the following functions does the myelin sheath perform for a nerve cell?
A. Insulation
B. Regeneration
C. Sensory perception
D. Nutrition
The myelin sheath is a protective membrane that wraps around parts of certain nerve cells.
Its fatty-protein coating provides protective insulation for your nerve cell like the plastic insulation covering that encases the wires of an electrical cord ².
This allows the electrical impulses to travel quickly and efficiently between one nerve cell and the next. The other options are incorrect because they do not describe the functions of the myelin sheath.
Regeneration, sensory perception, and nutrition are not functions performed by the myelin sheath for a nerve cell.
Therefore, the Correct Answer is A.
More Questions on TEAS 7 Science
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Q #1: An individual suffers severe blunt trauma to the thoracic cavity. Which of the following organs are at greatest risk from this injury?
A. Heart and lungs
B. Brain and spinal cord
C. Liver and stomach
D. Large and small intestines
Answer Explanation
The correct answer is a. Heart and lungs. The thoracic cavity contains the heart and lungs, which are at greatest risk from severe blunt trauma to this area.
a.The brain and spinal cord are not located in the thoracic cavity and are therefore not at greatest risk from blunt trauma to this area.
c.The liver and stomach are located in the abdominal cavity, which is below the thoracic cavity. While these organs may be affected by severe blunt trauma to the thoracic cavity, they are not at greatest risk.
d.The large and small intestines are also located in the abdominal cavity and are not at greatest risk from blunt trauma to the thoracic cavity.
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Q #2: Which of the following is an efferent neuron that is responsible for releasing a neurotransmiter that stimulates a muscle cell to contract?
A. Motor neuron
B. Interneuron
C. Sensory neuron
D. Neuroglia
Answer Explanation
An efferent neuron that is responsible for releasing a neurotransmitter that stimulates a muscle cell to contract is a motor neuron ². Motor neurons carry signals from the brain to the peripheral nervous system in order to initiate an action. The neurotransmitter acetylcholine (ACh) is released by motor neurons at the neuromuscular junction in skeletal muscle, causing the muscle to contract ³.
The other options are incorrect because they do not accurately describe the type of neuron responsible for releasing a neurotransmitter that stimulates a muscle cell to contract. Interneurons are found within the central nervous system and facilitate communication between sensory and motor neurons. Sensory neurons carry information from sensory receptors to the central nervous system. Neuroglia are support cells for neurons and do not transmit nerve impulses.
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Q #3: Which of the following substances is excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia?
A. Lysozymes
B. Urea
C. Water
D. Sebum
Answer Explanation
Urea is a waste product that is formed when proteins are broken down in the body. It is excreted by the kidneys in urine, but small amounts can also be excreted by sweat glands in sweat.
The other options are not substances that are excreted by sweat glands in response to the breakdown of proteins and the formation of ammonia. Lysozymes are enzymes that break down bacterial cell walls, water is a component of sweat but is not specifically related to protein breakdown, and sebum is an oily substance produced by sebaceous glands to lubricate the skin.
