Nokea
Which gland is often abnormal in patients with myasthenia gravis?
- A. thymus gland
- B. thyroid gland
- C. adrenal gland
- D. pituitary gland
Correct Answer: A
Rationale: The thymus gland, which plays a role in immune system development, is often abnormal in patients with myasthenia gravis. Thymic hyperplasia or thymoma is commonly associated with the condition, and thymectomy (surgical removal of the thymus) can improve symptoms in some cases.
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What neurotransmitter will result in constriction of the pupil?
- A. norepinephrine
- B. acetylcholine
- C. epinephrine
- D. serotonin
Correct Answer: B
Rationale: The correct answer is B: acetylcholine. Acetylcholine is the neurotransmitter responsible for causing constriction of the pupil. When acetylcholine binds to muscarinic receptors in the eye muscles, it triggers the muscles to contract, leading to pupil constriction. Norepinephrine (choice A) and epinephrine (choice C) are both involved in the fight-or-flight response and dilate the pupils. Serotonin (choice D) does not directly affect pupil constriction.
When assessing a patient's level of consciousness, which response would indicate a decreased level of consciousness?
- A. The patient is drowsy but can be easily aroused.
- B. The patient is alert and oriented.
- C. The patient responds quickly to verbal stimuli.
- D. The patient is fully awake and responsive.
Correct Answer: A
Rationale: A drowsy patient who can be easily aroused indicates a decreased level of consciousness. Alertness, quick responses, and full wakefulness are normal findings.
The vagus nerve
- A. Arises from the medulla as a single nerve
- B. Receives nucleus ambiguous fibres from the accessory nerve
- C. Supplies motor fibres to the diaphragm
- D. Supplies sensory fibres to the facial region
Correct Answer: B
Rationale: The vagus nerve receives motor fibers from the nucleus ambiguus, which also contributes to the accessory nerve. It innervates muscles of the pharynx and larynx.
Which of these statements about the peripheral nervous system is correct?
- A. The CNs enter the brain through the spinal cord.
- B. Efferent fibers carry sensory input to the central nervous system through the spinal cord.
- C. The peripheral nerves are inside the central nervous system and carry impulses through their motor fibers.
- D. The peripheral nerves carry input to the central nervous system by afferent fibers and away from the central nervous system by efferent fibers.
Correct Answer: D
Rationale: The correct answer is D because the peripheral nerves carry sensory input to the central nervous system by afferent fibers and motor commands away from the central nervous system by efferent fibers. This is known as the afferent-efferent division of the peripheral nervous system. Choice A is incorrect because cranial nerves (CNs) enter the brain directly, not through the spinal cord. Choice B is incorrect because efferent fibers carry motor commands away from the central nervous system, not sensory input. Choice C is incorrect because peripheral nerves are outside the central nervous system and do not carry impulses through motor fibers; instead, they carry motor commands through efferent fibers.
A microscopic gap between a pair of adjacent neurons over which nerve impulses pass when going from one neuron to the next is called:
- A. Neurotransmitter
- B. Synapse
- C. Axon
- D. None of the above
Correct Answer: B
Rationale: Synapse is the correct answer because it is the junction between two neurons where electrical or chemical signals are transmitted. Neurotransmitters are the chemicals that facilitate this transmission, but the gap itself is called the synapse.