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Ophthalmology > Physiology and Immunology > Flashcards

Physiology and Immunology Flashcards

(65 cards)

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1
Q

what is a choroid fissure

A

when developing arteries invaginate into the roof of the ventricle

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2
Q

What is the choroid plexus

A

made up of ependymal cells and vessels enlarging into villi

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3
Q

What is CSF made up of

A

mainly water

the rest is made up of brain interstitial fluid

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4
Q

How does the interstitial fluid get into the CSF

A

drains via perivascular spaces

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5
Q

What are the functions of CSF

A

Protects the brain - shock absorption
pH of CSF affects pulmonary ventilation and cerebral blood flow
transports hormones

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6
Q

what is the blood-CSF barrier

A

a leaky barrier that allows drainage of CSF into the subarachnoid space

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7
Q

What is the blood-brain barrier

A

a non leaky barrier

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8
Q

What does the blood-brain barrier consist of

A

capillary endothelium
its basal membrane
perivascular astrocytes

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9
Q

How does the blood-brain barrier work

A

there are tight junctions between the endothelial cells that doesn’t let anything pass

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10
Q

Where can a colloid cyst usually be found

A

posterior to the foramen of monroe in the anterior aspect of the 3rd ventricle

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11
Q

What is an ependymoma

A

a cancer derived from ependymal cells

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12
Q

What is a subdural haemorrhage

A

venous haemorrhage between the dura and arachnoid

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13
Q

What is an epidural haemorrhage

A

an arterial haemorrhage between the skull and the dura

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14
Q

What is a subarachnoid haemorrhage

A

blood leaking into the subarachnoid space

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15
Q

Hydrocephalus is

A

accumulation of CSF in ventricular system/ around the brain causing increased CSF pressure

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16
Q

What are the causes of hydrocephalus

A

over-production of CSF

obstruction

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17
Q

What is idiopathic intracranial hypertension also known as

A

pseudotumour cerebri

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18
Q

What does idiopathic intracranial hypertension present with

A

headache
visual disturbance
papilloedema
ICP on lumbar puncture with no imagining of hydrocephalus

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19
Q

What are the risk factors for IIH

A

obesity/ recent increase in weight

tetracycline

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20
Q

What is the function of aqueous humour

A

provides - oxygen

  • metabolites
  • HCO3 for buffering against H+ which is produced in anaerobic glycolysis of the cornea and lens
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21
Q

Where is aqueous humour produced

A

ciliary body

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22
Q

What is the ciliary body and posterior iris made up of

A

2 contrasting layers of epithelium (pigmented epithelium overlain by non-pigmented)

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23
Q

What does Carbonic anhydrase allow

A

production of HCO3

transport of HCO3 into the posterior chamber (along with Na, K, Cl and water)

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24
Q

what is the pathway of the retina

A

photoreceptors -> bipolar cells -> ganglion cells

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25
Where does horizontal cells get their input from
bipolar cells | photoreceptors
26
where does amacrine cells get their input from
bipolar cells ganglion cells other amacrine cells
27
What do photoreceptors do
transduction - change electromagnetic radiation (APs) into neural signals
28
In the dark/at rest, what happens to the Na
Na enters the outer segment and leaves via the inner segment, driven by the presence of K
29
What is the ratio of Na to K in the outer segment
Na=K
30
What is the dark current
cGMP gated Na channels are open in the dark and close in the light
31
What happens to the cell in the light
the channels on the outer segment of the photoreceptor close meaning Na can't enter so K>Na - this causes the cell to hyperpolarise (Vm becomes more -ve)
32
How is the brain able to perceive objects in the visual field
Due to the change in Na in the photoreceptors
33
Rhodopsin =
rods | made from retinal (Vit A derivative) and opsin (G protein coupled receptor)
34
where are rods present
on the discs in the outer segment of the photoreceptor
35
What does light to do the rods
changes 11-cis-rhodopsin to all-trans-rhodopsin (vitamin A)
36
what does all-trans-rhodopsin do
activates transducin which causes a molecular changed causing a decrease in cGMP - this in turn closes cGMP gated Na channels and hyperpolarisation of the cell
37
what is visual acuity
the ability to differentiate to distinct nearby points
38
How is visual acuity determined
by photoreceptor spacing and refractive power
39
What do rods do
``` see dim light achromatic (black and white) in peripheral retina high convergence high sensitivity to light low visual acuity ```
40
what do cones do
``` see daylight light chromatic (colours) in central retina (fovea) low convergence low light sensitivity high visual acuity ```
41
what is amblypoia
cortical blindness (lazy eye)
42
what can ambylopia be caused by
strabismus if not corrected in infancy
43
what is strabismus
where both eyes do not align when looking at an object
44
what is the treatment for strabismus
child has to wear a patch on their good eye for a couple of hours a day (so brain can properly develop both eyes) till they become of age to get surgery
45
What is Hebbs postulate
loss of binocularity (everything looks fuzzy)
46
How does hebbs postulate occur
when an axon is too close to another cell, it will excite that cell leaving the axon of that cell redundant
47
What are the layers of the tear film
mucin layer (non-adhesive) aqueous layer lipid layer
48
What does the blink reflex do
washes lacrimal fluid to the centre of the eye
49
Where are langerhans cells found
abundant in the corneal scleral limbus less in peripheral cornea absent in the central cornea
50
Lymphatic drainage of the eye is only found where
conjunctiva
51
The cornea and the sclera are
a tough collagen coat avascular no lymphatic drainage
52
what makes up the blood-ocular barrier
vitreous choroid retina
53
What is immune privilege
ares of the body that can tolerate an antigen without producing an inflammatory immune response
54
Which sites in the eye have immune privilege
``` cornea lens anterior chamber vitreous chamber subretinal space ```
55
what is anterior chamber associated immune deviation (ACAID)
protects the eye and visual axis from collateral damage of an immune response by suppression of a future response to infection
56
How doe ACAID work
produces CD4+ T and B cells that produce non-complement fixing Ab inhibits type 4 hypersensitivity which usually would secrete complement fixing Ab therefore, inhibits immune response
57
Where is ACAID present
cornea
58
What does ACAID do in cornea
``` means there is reduced MHC class 1 and no MHC class 2 - no blood or lymphatic vessels ```
59
What is sympathetic ophthalmia caused by
surgery/ trauma to one eye | immune (T cell mediated) response
60
what does sympathetic ophthalmia present as
bilateral granulomatous uveitis
61
What is the treatment for sympathetic ophthalmia
need to remove the damaged eye to prevent loss of both eyes
62
What is type 1 hypersensitivity and give an ocular example
immediate response mediated by IgE e.g. acute allergic conjunctivitis chemosis (oedema of conjunctiva)
63
What is type 2 hypersensitivity and given an ocular example
direct cell killing mediated by complement , NK cells and macrophages e.g. ocular cicatrical pemphigoid
64
What is type 3 hypersensitivity and given an ocular example
Immune complex mediated mediated by T, B cells and Ab e.g. autoimmune corneal melting
65
What is type 4 hypersensitivity and given an ocular example
delayed hypersensitivity mediated by Th cells e.g corneal graft rejection

Ophthalmology (8 decks)

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