Nokea
Which area of the brain-stem controls heart rate and breathing?
- A. reticular formation
- B. medulla
- C. pons
- D. thalamus
Correct Answer: B
Rationale: The medulla oblongata, located in the brainstem, controls vital autonomic functions such as heart rate, breathing, and blood pressure. It contains centers for regulating respiration and cardiovascular activity, making it essential for survival. Damage to the medulla can be life-threatening, as it disrupts these critical functions. The medulla also plays a role in reflexes like swallowing and vomiting.
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What is different when a lesion occurs in a lower motor neuron compared to in an upper motor neuron?
- A. Causes hyporeflexia and flaccidity
- B. Affects motor control of the lower body
- C. Arises in structures above the spinal cord
- D. Interferes with reflex arcs in the spinal cord
Correct Answer: A
Rationale: Lower motor neuron lesions typically result in hyporeflexia and flaccidity due to direct involvement of motor neurons.
Early symptoms of variant Creutzfeldt-Jakob Disease (vCJD) include changes in mood, temperament and behaviour followed by impairments in memory and concentration, and confused thinking. The infectious agent in vCJD is thought to be which of the following?
- A. MRSA.
- B. Prion.
- C. Ion.
- D. Hemaglobin.
Correct Answer: B
Rationale: Prions are abnormal, infectious proteins that cause neurodegenerative diseases like variant Creutzfeldt-Jakob Disease (vCJD). These proteins induce the misfolding of normal cellular proteins in the brain, leading to brain damage and the characteristic symptoms of vCJD, such as mood changes, memory loss, and cognitive decline. Prion diseases are incurable and ultimately fatal, making early detection and prevention critical.
Which of the following is the most effective drug for PD?
- A. Amantadine
- B. Carbidopa/levodopa
- C. Pramipexole
- D. Rasagiline
Correct Answer: B
Rationale: Carbidopa/levodopa is the most effective drug for managing Parkinson's disease symptoms, as it replenishes dopamine levels in the brain.
The corneal stroma:
- A. measures 500 um thick
- B. transmits 90% of the incoming light
- C. derives most of its oxygen from the precorneal tear film
- D. is acellular which accounts for its transparency
Correct Answer: A
Rationale: The corneal stroma is approximately 500 micrometers thick and is responsible for the majority of the cornea's thickness. It transmits most of the incoming light, but its transparency is due to the regular arrangement of collagen fibers and the presence of keratocytes, not because it is acellular.
The following are true about corneal sensation:
- A. the sensation is greatest at the apex and diminishes towards the limbus
- B. the temporal half of the cornea is more sensitive than the nasal half
- C. the Bonnet-Cochet aesthesiometer gives quantitative measure of the degree of hypoaesthesia
- D. all above
Correct Answer: D
Rationale: Corneal sensation is greatest at the apex, the temporal half is more sensitive, and the Bonnet-Cochet aesthesiometer quantifies hypoaesthesia. All statements are true.