8.2

Question 1

State the order of events/neurons in a typical reflex arc

Answer 1

Sensory neurons in receptors detect a stimuli which sends electrical impulses via relay neurons in the spinal cord. Relay neurons connect the sensory and motor neurons so the electrical impulses from sensory neurons ultimately causes a muscular reaction from an effector

Question 2

State the names of the antagonistic muscles that control iris size

Answer 2

Dilation - radial contract and circular relax
Constriction - circular contract and radial relax

Question 3

Describe the sequence of events that lead to iris dilation and constriction

Answer 3

Impulses sent from receptors within the eye cause the effector (circular or radial muscles) to contract while the antagonist relaxes causing either dilation or constriction