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Opthalmology > Physiology > Flashcards

Flashcards in Physiology Deck (24)
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1
Q

What sites of the brain do not have a BBB

A

pinneal gland

cirumventricular organs

2
Q

Where is CSF produced

A

n the secretory epithelium of the choroid plexus

3
Q

What is contained in normal CSF

A

it is clear and colourless
contains little protein
little immunoglobulins

4
Q

What is hydrocephalus

A

accumulation of CSF in the ventricular system or around the brain
susequent enlargement of one or more ventricles and increase in CSF

5
Q

What is normal pressure hydrocephalus

A

triad of dementia, incontinence and gait disturbances

6
Q

What is idiopathic intracranial hypertension

A

condition seen in obese females usually of childbearing age
can cause papilloedmea, headaches etc
no imaging features of hydrocephalus

7
Q

What is the purpose of the aqueous humour

A

a specialised fluid that bathes the structures within the eye
procides oxygen and metabolites and contains bicarbonate

8
Q

What is the function of bicarbonate in the aqueous humour

A

buffers the protons produces in the cornea and the lens

9
Q

What are the two epithelial layers in the ciliary body and posterior surface of the iris

A

the pigment epithelium of the retina

the non pigmented epithelium layer

10
Q

What happens when photoreceptors are exposed to light

A

they hyperpolarise

they are usually depolarised

11
Q

What enables the brain tp perceive light

A

the change in sodium with light (sodium channels closed in light and open in dark)

12
Q

What is different about photoreceptors compared to other neurons

A

they are usually at a depolarised resting membrane potential of -20 compared to -70 of most cells

13
Q

What happens to sodium channels when exposed to light

A

they close

14
Q

what happes to the membrane potential with light exposure

A

hyperpolarises

15
Q

What effect does light have on the visual pigment molecules

A

light converts 11 cis retinal to all trans retinal (vit A)

16
Q

What increases your visual acuity

A

cones

17
Q

What is used to see in dim light

A

rods

18
Q

Which has more convergence -rods or cones

A

rods

19
Q

What is used to see colour

A

cones

20
Q

Where are cones and rods situated

A

rods - periphery

cones- central retina (fovea)

21
Q

What colour do short wave cones see

A

blue

22
Q

What colour do middle wave cones pick up

A

green

23
Q

What colour do long wave cones percieve

A

red

24
Q

What tumours affect the production of CSF

A

colloid cysts
Pinealoma
Ependymomas (children usually)
Choroid plexus tumours (children usually)