Nervous System

ACh is the major neurotransmitter of the PSD; nicotinic receptors are always stimulatory; ACh binds to nicotinic and muscarinic receptors.

The parasympathetic division prepares the body for “rest and repose”, conserves energy and promotes non-emergency function.

The lens needs to be elastic in order to become thin (to view distant objects) and to become thick (to view objects that are within 1 m).

Atmospheric air pressure decreases as altitude increases. The air trapped in the middle ear remains at atmospheric pressure if we rapidly gain altitude, so this trapped air volume in the middle ear expands (Boyle’s law). This causes the ear drum to be uncomfortably deformed outwards. When the Eustachian tube (which is normally squashed flat) opens to allow some air to escape from the middle ear compartment, comfort is restored.

All cells require oxygen, so of course it can cross the BBB most pharmaceuticals cannot.

The medulla oblongata is where the pyramidal tracts cross over (decussate).

Choice A would be true of anaxonic neurons. Choice B would be true of unipolar neurons. Choice D would be true of bipolar neurons.

The “horns” contain grey matter which is the cell bodies of motor neurons. The dorsal horns contain sensory nuclei (cell bodies of neurons).

In myopia (near-sightedness) close objects are in focus but distant ones are not. It may be corrected by using a concave (diverging) lens.

Increasing the refraction of light will cause light rays from nearby objects to deviate more from their original path and so become focussed on the retina.