Nervous System and Neurons

The optic nerve (Cranial Nerve II) is the second cranial nerve and transmits visual information from the retina to the brain. The olfactory nerve (CN I) is first, and other nerves like abducens (CN VI) and trigeminal (CN V) have different numbers and functions.

The trigeminal nerve (CN V) is the fifth cranial nerve, responsible for sensation in the face and motor functions like biting and chewing. Occulomotor is CN III, facial is CN VII, and glossopharyngeal is CN IX.

The parasympathetic nervous system uses acetylcholine as its neurotransmitter at both preganglionic and postganglionic nerve endings. This cholinergic transmission is what produces 'rest and digest' effects like slowing heart rate and increasing digestion.

The olfactory nerve (Cranial Nerve I) is the first cranial nerve, responsible for the sense of smell. It's unique among cranial nerves as it can regenerate and conducts smell signals from the nasal epithelium directly to the brain.

In ulnar nerve injury, adduction of the thumb is impaired due to paralysis of the adductor pollicis muscle. The other options (claw hand, hypothenar atrophy, sensory loss) are all clinical findings that DO occur in ulnar nerve injury.

Fast axonal transport relies on microtubule tracks and molecular motors: kinesin (anterograde transport) and dynein (retrograde transport). Microfilaments (actin) participate in slow axonal transport. Neurofilaments are structural intermediate filaments that provide cytoskeletal support and do NOT participate in active transport.

Gangliosides are glycosphingolipids predominantly found in nerve cell membranes, particularly in the brain and nervous tissue. They play crucial roles in cell signaling and neural function. Option C 'carolia' appears to be a typo, possibly meaning 'cardiac'.

Acetylcholine is a neurotransmitter that carries nerve signals across the synaptic gap between neurons. The synapse is the specialized junction where transmission occurs, not the dendrites, axons, or cytons which are structural parts of neurons.

The soma (cell body) contains the nucleus and organelles necessary for basic cellular functions including protein synthesis. Axons and dendrites are specialized for signal transmission, while synaptic knobs are involved in neurotransmitter release.

Preganglionic sympathetic fibers release acetylcholine at their synapses with postganglionic neurons, making them cholinergic. This is true for all autonomic preganglionic fibers regardless of whether they are sympathetic or parasympathetic.

Meissner's Corpuscles are touch receptors located near the surface of the skin. 

The abducent nerve or abducent nerve (the sixth cranial nerve, also called the sixth nerve or simply CNVI) is a somatic efferent nerve that, in humans, controls the movement of a single muscle, the lateral rectus muscle of the eye.

The human brain contains roughly equal numbers of glial cells and neurons (approximately 1:1 ratio), contradicting older claims of 10:1 or 50:1. This ratio varies by brain region but balances overall.

Ans - 2

Neurons are indeed surrounded and supported by glial cells (glia). Glia provide structural support, nutrition, and insulation for neurons in the nervous system. This is a fundamental fact of neurobiology.