Gaps in the myelin sheath are called _______.
- A. nodes of Ranvier
- B. the synapse
- C. axonal interstices
- D. myelinoids
Correct Answer: A
Rationale: Nodes of Ranvier are small gaps in the myelin sheath along the axon of a neuron. These gaps allow for the rapid conduction of nerve impulses through a process called saltatory conduction, where the action potential 'jumps' from one node to the next. This increases the speed and efficiency of neural communication. Nodes of Ranvier are essential for proper nerve function and are found in both the peripheral and central nervous systems.
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The following signs occur in ipsilateral interruption of the cervical sympathetic trunk:
- A. enophthalmos
- B. ptosis
- C. vasodilatation in the skin of the face
- D. All above
Correct Answer: D
Rationale: Interruption of the cervical sympathetic trunk leads to Horner's syndrome, characterized by ipsilateral ptosis (drooping eyelid), miosis (pupil constriction), and anhidrosis (lack of sweating). Enophthalmos (sunken eye) and vasodilatation in the facial skin may also occur due to loss of sympathetic tone.
Chemicals called ________ are stored in neurons and released when the cell is stimulated by a signal.
- A. toxins
- B. cytokines
- C. chemokines
- D. neurotransmitters
Correct Answer: D
Rationale: The correct answer is D: neurotransmitters. Neurons store and release neurotransmitters in response to signals to communicate with other neurons or target cells. Neurotransmitters play a crucial role in transmitting signals across synapses. Toxins (A) are harmful substances, not involved in neuronal communication. Cytokines (B) and chemokines (C) are signaling molecules involved in immune responses, not neuronal communication. Therefore, the correct choice is neurotransmitters.
Which lobe of the cerebrum is located just above the ear?
- A. Parietal lobe
- B. Temporal lobe
- C. Frontal lobe
- D. Occipital lobe
Correct Answer: B
Rationale: The temporal lobe is situated near the ears.
Which is the largest branch of the internal carotid artery?
- A. ophthalmic artery
- B. anterior cerebral artery
- C. middle cerebral artery
- D. striate artery
Correct Answer: C
Rationale: The middle cerebral artery is the largest branch of the internal carotid artery and supplies a significant portion of the cerebral cortex, including areas responsible for motor and sensory functions.
Which type of seizure is most likely to cause death for the patient?
- A. Subclinical seizures
- B. Myoclonic seizures
- C. Psychogenic seizures
- D. Tonic-clonic status epilepticus
Correct Answer: D
Rationale: Status epilepticus is a life-threatening condition requiring immediate intervention