Exam 4: Vision

Question 1

What three muscles mediate eyelid opening and closing?

Answer 1

Orbicularis oculi, levator palpebrae superioris (LPS) and superior tarsal muscle

Question 2

T/F: orbicularis oculi and levator palpebrae superioris are smooth muscle

Answer 2

False; striated muscle

Question 3

T/F: superior tarsal muscle is smooth muscle

Answer 3

True

Question 4

What neurotransmitter/receptor combination acts on orbicularis oculi and levator palpebrae superioris?

Answer 4

Acetylcholine/nicotinic receptor

Question 5

What neurotransmitter/receptor combination acts on superior tarsal muscle?

Answer 5

Norepinephrins on alpha1 receptors

Question 6

What action maintains opening of the eyelid?

Answer 6

tonic activity of levator palpebrae superioris and superior tarsal muscles

Question 7

What muscle actions gently open the eye lid?

Answer 7

activation of the levator palpebrae superioris with inactivation of the orbicularis oculi

Question 8

What are the functions of blinking?

Answer 8

corneal lubrication, eye protection, visual formation processing

Question 9

What activity influences the patter generator that is responsible for the blinking reflex?

Answer 9

dopaminergic activity (responsible for motor control in the brain)

Question 10

What initiates the blink reflex?

Answer 10

touch to the cornea, bright light/rapidly approaching objects, loud sounds

Question 11

What are the three layers of tear production?

Answer 11

1) lipid secreted by oil glands in eyelids. 2) aqueous based solution from lacrimal gland. 3) Mucous from conjunctiva

Question 12

What half of the autonomic nervous system controls flow of tears?

Answer 12

parasympathetic