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PMCOL 343 > 5-autonomic-eyeball! > Flashcards

5-autonomic-eyeball! Flashcards

1
Q

what does morphine do to pupil

A

miosis

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2
Q

what does organophostate poisoning do to pupil

A

miosis

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3
Q

what does cocaine do to pupil

A

mydriasis

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4
Q

what does amphetamine do to pupil

A

mydriases

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5
Q

what is mydriasis

A

dilation of pupil

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6
Q

what is the role of the pupillary dilator muscle

A

cause mydriasis with alpha adrenoceptor stimulation. when contracted, it results in pupil dilation

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7
Q

what is the role of the iris spincter

A

site of action of the PSNS (where M3 receptors are found), when constricting, causes miosis (pinpoint pupils)

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8
Q

what kind of receptor stimulation happens with the iris sphincter

A

muscarinic M3 (Gq GPCR)

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9
Q

what kind of receptor stimulation happens with the circular pupillary dilator muscle

A

alpha

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10
Q

what kind of activation do ciliary muscles require

A

muscarinic

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11
Q

what does muscarinic activation do to ciliary muscles

A

contraction, more round lens, increased focusing power, accomodates for near vision (myopia)

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12
Q

what does the trabecular meshwork do

A

moves do that fluid can leave through the canal of schlemm

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13
Q

what does the canal of schlemm do

A

let fluid leave the eye

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14
Q

what causes the trabecular meshwork to move

A

ciliary muscle activation

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15
Q

how do ciliary muscles help with removing aqueous humor

A

puts tension on trabecular meshwork which opens pores to let outflow of aqueous humor in canal of schlemm

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16
Q

what does the ciliary epithelium do

A

produces the aqueous humor

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17
Q

what kind of receptors stimulate the ciliary epithelium? what happens?

A

beta, resulting in increased secretion of aqueous humor

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18
Q

how do beta blockers reduce IOP

A

reduces aqueous humor release from the ciliary epithelium (ciliary epithelium has beta adrenergic receptors)

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19
Q

how do muscarinic agonists reduce IOP

A

because it contracts ciliary muscles which puts tensions on the trabecular meshwork to open pores and let aqueous humor out into the canal of schlemm

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20
Q

what is glaucoma and what can it cause

A

elevated IOP and it can cause optic nerve damage and blindness

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21
Q

what are the two types of glaucoma

A

open angle and angle closure glaucoma

22
Q

what is open angle glaucoma

A

high pressure between cornea and iris, common and easily treated

23
Q

what is angle closure glaucoma

A

high pressure between ciliary body and iris

24
Q

what is the course of treatment for open angle glaucoma (4)

A
  • topical beta blocker (stop ciliary body secretion)
  • cholinergic agonist/cholinesterase inhibitor (trigger M3 on ciliary muscle)
  • add adrenaline or apraclonidine (reduces blood flow to ciliary body)
  • carbonic anhydrase inhibitor (affects ciliary body secretion)
25
Q

why is it safe to take glaucoma meds if you have systemic circulation issues

A

the eye drops have very poor access to systemic circulation

26
Q

what is Timolol (drug class)

A

beta blocker

27
Q

describe the effectsof timolol

A

beta blocker with no local anesthetic effects like propanolol
reduces secretion of aqueous humor from ciliary body and lower IOP

28
Q

what is pilocarpine (drug class)

A

muscarinic agonist

29
Q

what does pilocarpine do

A

cause ciliary muscle contraction

increase outflow of aqueous humor into circulation, reduce IOP

30
Q

what are the untoward effects of pilocarpine

A

since pilocarpine is a muscarinic agonist (PSNS), it causes miosis (by iris sphincter)

myopia (by ciliary muscle)

31
Q

what is physostigmine

A

anticholinesterase

32
Q

what does physostigmine do to eye

A

since it’s an anticholinesterase, ciliary muscle contraction via M3 receptors, increase outflow of aqueous humor, reduce IOP

33
Q

what does apraclonidine do

A

vasoconstrict via alpha 1, reduce blood flow to ciliary body, less aqueous humor secreted, IOP decreased

34
Q

what do cannabinoids do to eye

A

lower IOP likely by relaxing the trabecular network

35
Q

what is anandamide? describe the mechanism of action

A

endogenous ligand of the CB1 and CB2 receptors, activates Gi signalling pathway resulting in decreased NT release

36
Q

what signalling pathway do CB1 receptors use?

A

Gi which reduces NT release by activating Ca2+ and GIRK channels

37
Q

what direction does GIRK channels go

A

releases K+ from nerve terminal!

38
Q

what does atropine do to the eye

A

muscarinic antagonist, so dilate pupil for ocular examination

39
Q

what kind of drug is atropine

A

muscarinic antagonist

40
Q

what causes Horner’s syndrome

A

head trauma or stroke in brainstem

even if the damage is unilateral

41
Q

can damage to parasympathetic nerves cause horners syndrome

A

no

42
Q

what characterizes horners syndrome

A

interruption of oculosympathetic pathway resulting in ocular sympathetic dennervation somewhere between hypothalamus and eye

43
Q

what are the 3 neurons that could be damaged to cause horners syndrome

A

1-hypothalamus to spinal cord
2-sympathetic preganglionic neuron
3-sympathetic ganglion neuron

44
Q

what would you expect cocaine to do to the pupil

A

cause dilation (indirect sympathomimetic)

45
Q

if cocaine doesn’t cause pupil dilation, where would the lesion be

A

neurons 1 2 or 3

46
Q

how can you use amphetamines to test for horners syndrome

A

test neuron 3
-if it is intact, the pupil will dilate (it releases NA REGARDLESS of the condition of neuron 1 and 2 or sympathetic outflow to neuron 3)

47
Q

in summary, what do alpha adreoceptor agonists do to eye

A

lowers IOP (decrease flow to ciliary body) by causing smooth muscle contraction via alpha 1 receptors
mydriases (increase pupil size from pupillary dilator/iris radial muscle)

48
Q

in summary, what do muscarinic agonists do to eye

A

miosis (pupillary constrictor/iris sphincter)
myopia (ciliary muscle contraction, accomodation for near vision)
lower IOP (activate M3 receptors -contract ciliary muscle - tension on trabecular meshwork - aqueous humor squeezed out into circulation)

49
Q

in summary, what do beta adreoceptor antagonists do to eye

A

decrease activation of beta receptors on ciliary epithelium, decrease Gs response, lower IOP (blocks humor production by ciliary body)

50
Q

why can atropine be bad for glaucoma

A

since atropine is a muscarinic antagonist, it will block PSNS (sympathomimetic effects), beta receptors on ciliary epithelium are activated

it can relax the ciliary muscle

PMCOL 343 (31 decks)

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