Eye

Question 1

6-OHDA: stands for? what?

Answer 1

6 hydroxydopamine, destroys temporarily sympathetic nerve terminals

Question 2

6-OHDA: what do you see?

Answer 2

eye originally dilated: apply 6-OHDA = see miosis (pupil constriction) because sympathetic innervation is destroyed. after several weeks, eye recovers and dilation is seen again

Question 3

morphine/organophosphate poisoning: eye effects?

Answer 3

miosis because morphine stimulates parasympathetic outflow, and organophosphate is an anticholinesterase

Question 4

sympathetic innervation: which ganglion?

Answer 4

sympathetic effects are via the superior cervical ganglion

Question 5

3 neuron pathway?

Answer 5

hypothalamus to IML in SC. SC to superior cervical ganglion (preganglionic cholinergic neuron). SCG to eye (noadrenergic post ganglionic)

Question 6

parasympathetic: which ganglion? which nucleus?

Answer 6

ciliary ganglion. Edinger-Westphal nucleus, for rapid reflex

Question 7

eye under what tone

Answer 7

parasympathetic

Question 8

what does the ciliary muscle do

Answer 8

moves lens to focus eye (for near/far vision). contraction of CM also pulls on trabecular meshwork = outflow of humour through Canal of Schlemm to circulation

Question 9

autonomic nervous system: how many targets in they eye?

Answer 9

3 different muscles: pupillary dilator, pupillatry constrictor, ciliary muscle and 1 type of secretory epithelium: ciliary epithelium

Question 10

pupillary dilator: name of muscle? symp or parasymp? what receptor and what effect?

Answer 10

iris radial muscle; sympathetic. alpha-adrenoreceptor stimulation results in mydriasis aka pupil dilation

Question 11

puillary constrictor: name of muscle? symp/parsymp? receptor + effect?

Answer 11

iris sphincter muscle. parasymapthetic so muscarinic stimulation = miosis (pupil constriction)

Question 12

ciliary muscle: what causes contraction? 2 roles?

Answer 12

muscarinic stimulation = contraction. accommodates for near vision (myopia). and creates tension on trabecular meshwork (decreased IOP)

Question 13

ciliary muscle and IOP?

Answer 13

contraction = tension in trabecular meshwork; pores open = outflow of aqueous humour through canal of Schlemm to systemic circulation. IOP decreases; so is important for treatment of glaucoma

Question 14

ciliary epithelium: what receptor and effect? inhibition of receptor?

Answer 14

beta-adrenoceptor stimulation causes increased secretion of aqueous humor from ciliary body. beta blockers reduce secretory activity and thus reduce IOP.

Question 15

what two things are useful for glaucoma

Answer 15

muscarinic agonists (to affect ciliary muscles) and beta blockers (to reduce secretion)

Question 16

glucoma: what? can cause?

Answer 16

elevated intra ocular pressure. optic nerve damage and blindness

Question 17

two forms of glaucoma

Answer 17

more common treatable: open angle (high pressure between cornea + iris. less common: angle closure glaucoma (high pressure between ciliary body and iris)

Question 18

sequence of typical treatment for open angle glaucoma (4)

Answer 18

topical therapy with beta blocker. cholinergic agonist or cholinesterase inhibitor. adrenale/apraclonidine. carbonic anhydrase inhibitor.

Question 19

beta blocker: effect for glucoma?

Answer 19

topical application (so less systemic effects) = reduces secretion of aqueous humor from ciliary body; lowers IOP

Question 20

muscarinic agonists: effect for glaucoma?

Answer 20

ciliary muscle contraction = increased outflow of aqueous humour into circulation - reduced IOP

Question 21

2 untoward effects of using muscarinic agonists to treat glaucoma

Answer 21

miosis (reduced pupil size due to effects on ciliary iris sphincter). myopia (because of action on ciliary muscle)

Question 22

anticholinesterase: effect for glaucoma?

Answer 22

increase cholinergic/parasymp = ciliary muscle contraction, increased outflow of aqueous humour = reduce IOP

Question 23

adrenaline/apraclonidine effect for glaucoma?

Answer 23

vasoconstrictors so decrease blood flow to ciliary body. alpha receptor effect. secretion of aqueous humor decreased, IOP decreased