Impulse conduction is fastest in neurons that are:
- A. myelinated
- B. unmyelinated
- C. sensory
- D. motor
Correct Answer: A
Rationale: Myelinated neurons conduct impulses faster than unmyelinated neurons due to saltatory conduction, where the signal jumps between nodes of Ranvier. Sensory, motor, and cerebral neurons can be myelinated or unmyelinated, but myelination is the key factor for speed. Thus, A is the correct answer.
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Regarding the cranial nerves
- A. The trigeminal nerve is purely sensory
- B. The abducens nerve traverses the foramen lacerum
- C. The trochlear nerve supplies the superior oblique muscle only
- D. The hypoglossal nerve exits the skull through the foramen magnum
Correct Answer: C
Rationale: The trochlear nerve (IV) innervates only the superior oblique muscle, which depresses and abducts the eye. It is the only cranial nerve that exits dorsally from the brainstem.
The anal reflex mainly depends on which segment
- A. S1
- B. S2
- C. S3
- D. S4
Correct Answer: C
Rationale: The anal reflex tests the S3 and S4 nerve roots, which innervate the external anal sphincter. This reflex is important in assessing sacral nerve function.
If a nurse observes a sudden change in a client's vital signs, what immediate step should the nurse take?
- A. Inform the physician
- B. Change the environmental settings of the client
- C. Alter the diet intake of the client
- D. Decrease the physical activity of the client
Correct Answer: A
Rationale: Immediate medical attention is necessary for significant changes in vital signs.
Regarding the blood supply of the cerebral cortex
- A. Middle cerebral is contralateral arm, leg and speech areas
- B. Anterior cerebral is contralateral leg, micturition and defaecation
- C. Middle cerebral is ipsilateral arm, face and vision
- D. Posterior cerebral is ipsilateral vision
Correct Answer: B
Rationale: The anterior cerebral artery supplies the medial surface of the brain, including areas responsible for motor and sensory functions of the contralateral leg. It also influences micturition and defecation.
What is another name for the preganglionic sympathetic fibers that project to the heart?
- A. solitary tract
- B. vasomotor nerve
- C. vagus nerve
- D. cardiac accelerator nerve
Correct Answer: D
Rationale: The correct answer is D: cardiac accelerator nerve. Preganglionic sympathetic fibers that project to the heart are part of the cardiac accelerator nerves, which increase heart rate and force of contraction. The other choices are incorrect because:
A: solitary tract - involved in transmitting sensory information related to taste and visceral sensations.
B: vasomotor nerve - regulates blood vessel tone and blood pressure.
C: vagus nerve - part of the parasympathetic nervous system and slows down heart rate and decreases force of contraction.