MLT GlobePhysiology: Nervous system & special senses – page 4
68 Physiology MCQs on Nervous system & special senses with answers and explanations.
Electrical stimulation along the medial forebrain bundle gives animals a strong sense of reward. Which hypothalamic regions are most strongly involved?
Reward centres lie along the medial forebrain bundle, especially the lateral and ventromedial hypothalamic nuclei. Supraoptic and paraventricular nuclei make ADH and oxytocin; the suprachiasmatic nucleus sets circadian rhythm.
A patient has a tremor that appears when reaching for an object and worsens near the target. The lesion is most likely in the:
Intention tremor is a sign of cerebellar dysfunction. Basal ganglia lesions give resting tremor, rigidity, involuntary movements and postural problems.
Which function is NOT carried out by the brainstem?
The brainstem handles breathing, cardiovascular control, posture, equilibrium and eye movements. Voluntary movements are started by the cerebral motor cortex.
Which sensation travels up the dorsal columns on the same side of the spinal cord and crosses only in the medulla?
Proprioception, vibration and fine touch travel in the dorsal columns and decussate in the medulla. Pain, temperature and crude touch cross in the spinal cord (spinothalamic tracts).
Postganglionic sympathetic fibres to sweat glands are unusual because they release:
Most sympathetic postganglionic neurones release noradrenaline, but those supplying eccrine sweat glands are cholinergic. The sympathetic outflow is thoracolumbar, not craniosacral.
A few days after a peripheral nerve is cut, what happens in the segment distal to the injury?
In Wallerian degeneration the distal axon and myelin break down and are removed by macrophages and Schwann cells, which then guide regrowth.
Microglia, the resident phagocytes of the central nervous system, originate from which precursor?
Fate-mapping shows microglia colonise the embryonic brain from yolk-sac erythromyeloid progenitors and self-renew locally. Astrocytes and oligodendrocytes, not microglia, are neuroectodermal.
Taste signals relayed through the thalamus reach the primary gustatory cortex, which is located in the:
Gustatory fibres synapse in the nucleus of the solitary tract, then the thalamus (VPM), and project to the anterior insula and frontal operculum. The occipital lobe processes vision.