Question

Parasympathetic Pupillary light reflex is a 4 neuron arc. Name the arcs and what they do

Options:
A) Afferent arc - Carries sensory signals from retina to the brain
B) Efferent arc - Initiates pupillary constriction via ciliary ganglion
C) Preganglionic arc - Carries signals from Edinger-Westphal nucleus to ciliary ganglion
D) Postganglionic arc - Conveys signals from ciliary ganglion to iris sphincter muscle

Answer 1

The Parasympathetic Pupillary Light Reflex is a complex 4-neuron arc involving afferent, preganglionic, postganglionic, and efferent arcs. These arcs work together to regulate the constriction of the pupil in response to bright light.

Step-by-step explanation:

The Parasympathetic Pupillary Light Reflex is a 4-neuron arc that controls the constriction of the pupil in response to bright light. The arcs involved are:

1. Afferent arc: This arc carries sensory signals from the retina to the brain through the optic nerve.
2. Preganglionic arc: This arc carries signals from the Edinger-Westphal nucleus to the ciliary ganglion through the oculomotor nerve.
3. Postganglionic arc: This arc conveys signals from the ciliary ganglion to the iris sphincter muscle, stimulating pupillary constriction.
4. Efferent arc: This arc initiates pupillary constriction by activating the circular fibers of the iris through the ciliary ganglion.