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Neuro > Vision, Special Sense And Pharmacology > Flashcards

Vision, Special Sense And Pharmacology Flashcards

1
Q

Why do some drugs reversibly change between ionised and non-ionised?

A

To allow them to cross lipid membranes (ionised cannot pass lipid membrane)

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2
Q

Give 5 main ideal properties of local anaesthetics

A

Reversible, non-irritant to surrounding tissues, rapid onset, readily metabolised, slowly removed from site of action

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3
Q

What is analgesia

A

Loss of response to pain

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4
Q

Why is IV route used for general anaesthetics?

A

Inhaled route would be too slow and have a short half life

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5
Q

Give two IV general anaesthetic drugs

A

Thiopentone and Propofol

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6
Q

Give 2 inhaled general anaesthetic drugs?

A

Isoflurane and Nitrous Oxide

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7
Q

Why can Nitrous oxide not be used on its own as a general anaesthetic?

A

95% conc for induction which would cause asphyxia

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8
Q

Where do the optic nerves cross?

A

Optic chiasm

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9
Q

Where do the optic fibres first synapse?

A

Lateral geniculate

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10
Q

Where do the majority of fibres pass through when they leave the lateral geniculate?

A

Optic radiation

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11
Q

Why do some fibres from the lateral geniculate not pass through the optic radiation?

A

The pass to other centres which help aid eye movement

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12
Q

What happens to fibres at the optic chiasm?

A

The medial optic fibres cross over while the lateral fibres stay ipsilateral so the right LGN only receives light from the right and vice versa

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13
Q

What information do fibres in the lower half of the optic radiation carry?

A

Top of the visual field

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14
Q

Where do fibres in the lower half of the optic radiation pass over?

A

Temporal horn of the lateral ventricle to form meyers loop

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15
Q

What is akinetopsia?

A

Loss of perception of movement?

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16
Q

What may lesions of the parietal pathway cause?

A

Akinetopsia

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17
Q

What do circular eye muscles do and what innervates them?

A

Constrict the pupil, innervated by pns

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18
Q

What do radial eye muscles do and what innervates them?

A

Dilate the pupil, innervated by sns

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19
Q

What effect would activation of Muscarinic receptors have on the eye?

A

Contract via PNS

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20
Q

Give an example of a drug that would constrict the pupil AND accommodate the lens for near vision along with one to reverse this

A

Pilocarpine, reversed by tropicamide

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21
Q

Give a drug that would dilate the pupil with no effect on the lens

A

Phenylephrine (adrenergic receptors)

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22
Q

What is tonometry?

A

Measuring eye pressure

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23
Q

What is gonioscopy?

A

Measuring the angle between cornea and ciliary body

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24
Q

What causes blindness in glaucoma?

A

Optic nerve damage

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25
Q

What drug can be used to decrease aqueous humour formation?

A

Apraclonidine

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26
Q

Give a sodium channel blocker used in epilepsy

A

Carbamazepine

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27
Q

How do barbiturates help in epilepsy? Give an example of one

A

Increase duration of GABAa channel opening, phenobarbitone

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28
Q

Give 3 examples of prophylactic migraine treatment

A

B-blockers, Antiepileptics, TCAs

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29
Q

What drugs can be used for acute migraine treatment?

A

Triptans, NSAIDs, antiemetics

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30
Q

How does sumatriptan work?

A

Acts of 5HT1b/d to inhibit trigeminal nerve transmission and constrict smooth muscle around the cranial and basilar arteries

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31
Q

What is rumination

A

Repetitive regurgitation of recently ingested food to the mouths followed by re swallowing or expulsion

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32
Q

How do dopamine antagonists work to reduce vomiting?

A

Act on the CTZ to reduce the efffect of dopamine

33
Q

how do anaesthetics act on the brain?

A

They have a descending action on brain centers, the higher brain centers- reasoning, inhibition, sensory and motor skills, consciousness and memory are inhibited

34
Q

characteristics of propofol

A

high lipid solubility, very good distribution, high potency, rapid action due to high perfusion rate of the brain,

35
Q

What is entonox?

A

Entonox is a 50:50 mixture of oxygen and nitrous oxide. It is most commonly used for dental procedures, dressing changes, and obstetric anesthesia.

36
Q

pre medication before surgery

A

antimuscarinic/antihistamine- reduce gut secretions and motility
opioid analgesics- reduces intra and post op pain
sedative e.g temazepam - relaxes patient, anterograde amnesia
antiemetics

37
Q

what is the anaesthesia triad?

A

anaesthetics, NMJ blockers (and anticholinesterase) , analgesics

38
Q

how do local anesthetics work?

A

They prevent sodium channels from opening, thus blocking action potentials. They cause a reversible block along conduction fibres

39
Q

how is procaine used as a local anesthetic?

A

first true local anesthetic, no vasoconstriction, poorly absorbed from mucus membranes- not now used

40
Q

analgesic opioid examples and their roles

A

fentanyl- very potent, for chronic breakthrough pain
morphine- standard opioid, usually given IV
codeine - less potent , better oral absorption
pethidine- rapid acting,often used in obsteterics
tramadol- moderate potency opioid,

41
Q

how do opioids cause respiratory depression

A

acts in medulla to decrease rate and depth of breathing, especially seen in more lipid soluble opioids

42
Q

how do opioids cause nausea and vomiting?

A

They stimulate the chemoreceptor trigger zone, usually tolerance develops

43
Q

how do opioids cause cough suppression?

A

they have antitussive action, inhibit cough centre in the medulla

44
Q

drugs used for treatment of migraines

A

non specific- NSAIDs, antiemetics
specific- triptans
simple analgesic in combination with 5 HT-1 and antiemetics

45
Q

how do triptans help migraines?

A

triptans act on 5 HT1 B and D receptors, inhibits trigeminal nerve transmission , constricts vascular smooth muscle around cranial and basilar arteries

46
Q

antiemetics for acute migraines

A

dopamine antagonists-metoclopramide
antihistamines

47
Q

drugs to treat sickness in pregnancy and why we treat

A

severe vomiting- antihistamines- promethazine
2nd line- dopamine antagonist
usually self limiting but treat if persistent as can lead to vitamin deficiency and slowed fetal development

48
Q

what happens in lens accommodation?

A

focusing on near objects –> ciliary muscles tighten, lens flattened
focusing on distance –> ciliary body relaxes, lens stretched

49
Q

why does accommodation get worse with age?

A

elasticity of lens are damaged by UV oxidation due to sunlight exposure, decreases near point acuity

50
Q

Describe open angle glaucoma.

A

most common type of glaucoma, makes up 90% of cases, the trabecular meshwork becomes blocked by matrix debris, reducing outflow

51
Q

describe closed angle glaucoma

A

In closed angle glaucoma, the ciliary body is pushed forward to act as a physical block of the drainage of aqueous fluid that increases intraocular pressure, which impinges on the optic nerve causing damage
more common in long sighted people

52
Q

non drug method to treat glaucoma

A

laser ablation of trabecular meshwork, increases the drainage of aqueous fluid by punching holes into the matrix

53
Q

sodium channel blocker drugs in epilepsy

A

carbamazepine
phenytoin
lamotrigine
lacosamide
valproate

54
Q

What is carbamazepine? plus side effects

A

most widely used epilepsy drug,
S/E- some sedation, dizziness, liver affects- CYP450- lots of potential drug interactions,

55
Q

What is phenytoin? plus side effects

A

anticonvulsant drug used in ER, adminstered as an IV
narrow therapeutic range, CYP450- many drug interactions
S/E- ataxia, sedation, double vision, hypersensitivity rash
teratogenic -birth defects- should not be given to women of child bearing age

56
Q

What is Lamotrigine?

A

sodium channel blocker used in epilepsy but also has affects on calcium channels
no affect on CYP450- less drug interactions
side effects are rare

57
Q

use of barbiturates

A

good at treating status epilepticus
phenobarbitone increases duration of GABA channel opening
other barbiturates (thiopentone, propofol)- used to treat status epilepticus
S/E- marked sedation, CYP450- lots of drug interactions

58
Q

Mechanism of Levetiracetam

A

binds SV2A, a synaptic vesicle glycoprotein, reducing transmitter release
also inhibits presynaptic Ca2+ channels
add on therapy for tonic clonic seizures

59
Q

What are the typical antipsychotics?

A

dopamine receptor antagonists
D2- most effective
also D1, 3 and 4

60
Q

What are the atypical antipsychotics?

A

they block 5-HTA, glutamate receptors, reduce negative features

61
Q

Mechanism of antipsychotics?

A

blockade of D2 receptors in the mesolimbic and mesocortical pathways
improve positive features
atypical- block 5-HT2 in mesolimbic system - reduce negative features

62
Q

main classes of antipsychotics

A

phenothiazines
non-phenothiazines
atypical drugs

63
Q

Give an example of a phenothiazine

A

Fluphenazine

64
Q

Give an example of a non phenothiazine

A

Haloperidol

65
Q

Give an example of an atypical antipsychotic

A

Clozapine

66
Q

What is L-DOPA?

A

dopamine precursor that is converted to dopamine by DOPA decarboxylase

67
Q

what is MAO?

A

monoamine oxidase- two types
A- mainly NA and 5-HT2 breakdown
B- mainly dopamine breakdown

68
Q

What are MAOB inhibitors?

A

Selegiline
Rasagiline
they prolong dopamine survival within NS

69
Q

describe SSRIs

A

selective serotonin reuptake inhibitors, e.g sertaline, citalopram, fluoxetine
side effects- sexual dysfunction
relatively safe in overdose

70
Q

describe SNRIs

A

serotonin noradrenaline reuptake inhibitors
e.g. duloxetine, venlafaxine
marginally more effective than SSRIs but more side effects

71
Q

describe TCAs

A

tricyclic acid antidepressant drugs
e.g. amitriptyline
also block post synaptic receptors like muscarinic
troublesome side effects and unsafe in overdose

72
Q

use of lithium

A

acute treatment of manic and hypomanic episodes
prophylaxis of bipolar disorder
improves antidepressants and antipsychotics
reduces impulsivity, aggression and suicidal tendencies in all mental health patients

73
Q

adverse effects of lithium

A

thirst, polyuria, fine tremor, weight gain
worsening of dermatology symptoms
hypothyroidism
renal problems

74
Q

drugs used in insomnia

A

benzodiazepine hypnotics, cyclopyrrolones, melatonin receptor agonists, antihistamines, antidepressants

75
Q

drugs used in anxiety disorders

A

SSRIs, SNRIs, benzodiazepine anxiolytics, TCAs, MAOIs, antipsychotics, beta blockers,

76
Q

role of barbiturates

A

use in severe intractable insomnia in those already using barbiturates

77
Q

How do barbiturates work?

A

increase duration of Cl- channel opening, prolonged hyperpolarization

78
Q

adverse effects of benzodiazapines

A

dangerous when combined with alcohol or barbiturates
memory disturbance
impaired driving ability
potentially disinhibiting
tolerance to hypnotic effect
discontinuation symptoms
recommended for short term only due to risk of dependence

Neuro (6 decks)

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