It is a type of nerve cell that protects CNS from infection and becomes phagocytic in response to inflammation:

Correct Answer: C

Rationale: Microglia are CNS immune cells that phagocytose debris and pathogens during inflammation. Schwann cells myelinate PNS axons, ependymal cells produce CSF, and astrocytes support the BBB.

Correct Answer: D

Rationale: Sympathetic stimulation promotes glycogenolysis, spleen contraction, and adrenal catecholamine release (fight-or-flight), but reduces salivary secretion (dry mouth). Profuse salivation is parasympathetic.

Correct Answer: C

Rationale: Isoproterenol (isoproteranol) is a beta-adrenergic agonist, stimulating β receptors (e.g., heart, lungs). Methoxamine is α₁-specific, acetylcholine is cholinergic, atropine blocks muscarinic.

Correct Answer: B

Rationale: Atropine blocks parasympathetic muscarinic receptors, reducing vagal tone and increasing heart rate. Salivation and intestinal activity decrease, cardiac strength is unaffected.

Correct Answer: D

Rationale: Abducens (VI) innervates the lateral rectus eye muscle, not facial muscles (facial nerve, VII). Other pairings are correct.