What does a mechanically gated channel respond to?

Correct Answer: A

Rationale: Mechanically gated channels open in response to physical stimuli, such as pressure or stretch (e.g., in touch receptors). Chemical stimuli affect ligand-gated channels.

Correct Answer: D

Rationale: The medulla oblongata extends through the foramen magnum, connecting the brain to the spinal cord. It lies below the pons, not between midbrain and pons, and has multiple cranial nerves (e.g., IX, X, XII), not just trigeminal (V). Pyramids are medial to olives.

Correct Answer: A

Rationale: Parasympathetic innervation via pelvic splanchnic nerves (S2-S4) relaxes the sphincter and contracts the detrusor for urination. Sympathetic innervation (T11-L2, not L3-L4) inhibits the bladder, and sensation travels via both systems.

Correct Answer: C

Rationale: The great toe is supplied by the L5 dermatome, covering the lateral leg and dorsal foot. L4 supplies the medial foot, and S1 the lateral foot.

Correct Answer: A

Rationale: Brown-Sequard syndrome (cord hemisection) causes ipsilateral motor/touch/proprioception loss (corticospinal/dorsal columns) and contralateral pain/temperature loss (spinothalamic). The cord ends at L1-L2, and corticospinal is key.