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Opthamology > Physiology > Flashcards

Physiology Flashcards

1
Q

Colour and components of CSF

A

clear and colourless composed mainly of water

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2
Q

what produces CSF

A

secretory epithelium of the choroid plexus in the ventricles of the brain

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3
Q

How much CSF is there and how often is it replaced?

A

there is about 150cm3 and it is replaced 3-4 times daily

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4
Q

what does the CSF supply/remove

A

supplied ions, water and amino acids

removes metabolites

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5
Q

circulation of CSF

A

produced in the choroid plexus in the ventricles, circulates in the subarachnoid space and is absorbed in the venous circulation

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6
Q

How do you obtain CSF fluid to analyse

A

lumbar puncture

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7
Q

major functions of the csf

A

1) mechanical protection- shock absorber so the brain floats in the cranial cavity
2) homeostatic function- pH of the CSF affects pulmonary ventilation and cerebral blood flow. also transports hormones
3) circulation- minor exchange for nutrients and waste products between circulation and brain tissue

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8
Q

in embryonic development what gives rise to the brain and spinal cord?

A

the neural canal cavity

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9
Q

What are choroid cells and what are they produced from?

A

Choroid cells are specialised secretory cells that produce CSF. the choroid plexus develops from cells in the walls of the ventricle.

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10
Q

How does the choroid plexus develop?

A

Developing arteries invaginate the roof of the ventricles to form the choroid fissure. the ependymal cells involved along with the artery enlarge into villi (finger like projections) and from the choroid plexus

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11
Q

Where are choroid plexuses found in the adult brain?

A

lateral ventricles and 3rd and 4th ventricle

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12
Q

What ions are transported across the epithelium from blood to CSF in CSF secretion? How does this work?

A

Na, Cl and HCO3
Depends on active Na transport across cells into the csf and the electrical gradient pulls along CL
both ions drag water via osmosis

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13
Q

Is CSF production active or passive? does it depend on arterial BP?

A

It is an active secretory process

It is NOT DIRECTLY dependent on arterial BP

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14
Q

Ion differences between blood and CSF

A

CSF has lower K, glucose and much lower protein than blood but higher Na and higher Cl

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15
Q

what allows CSF to be secreted from the ventricles?

A

Pores:
mainly the medial and lateral aperture but there are 4 in total:
interventicular foramina of Monroe (lateral ventricles to 3rd ventricle)
cerebral aqueduct of sylvius ( 3rd ventricle to 4th)
foramen of magendie (median aperture): fourth ventricle to subarachnoid space
foramen of luschka (lateral aperture) fourth ventricle to subarachnoid space

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16
Q

Production and circulation of CSF

A

CSF is formed in the choroid plexus of each lateral ventricle. it flows to the third ventricle through the interventricular foramen. more CSF is added by the choroid plexus in the ROOF of the 3rd ventrcicle. It then flows through the cerebral aqueduct into the 4th ventricle- more CSF is added by the choroid plexus in the 4th ventricle. CSF then enters the subarachmoid space through 3 opening in the roof of the 4th ventricle

17
Q

What are the 3 openings in the roof of the 4th ventricle

A

single median aperture: foramen of magendie

paired lateral aperture: foramen of luschka

18
Q

How much CSF is produced and absorbed every day

A

500- pressure and volume remains constant

19
Q

Where does CSF flow to after the ventricular system

A

CSF flows into the subarachnoid space between the arachnoid and pia mater then goes to venous circulation through arachnoid granulations into the superior sagittal sinus

20
Q

What is tighter the BBB or BCSFB

A

BBB

21
Q

What is the BBB made up of

A

capillary endothelium and its basal membrane

perivascular astrocytes

22
Q

What junctions are present at the BBB and what is their purpose?

A

tight junctions- prevents paracellular movement of molecules (eg through the intracellular space in contrast to transcellular transport where it travels through the wall)

23
Q

What are circumventricular organs and an example

A

No BBB- allow the link between the CNS and peripheral blood flow eg pineal gland

24
Q

what are colloid cysts

A

tumours arising almost always at the interventricular foramen

25
Q

what are ependymonas

A

tumours arising from ependymal cells lining ventricles

26
Q

What are the different types of ventricular haemorrhages

A

Epidural: arterial bleed between skull and dura mater
Subdural: venous bleed between the dura mater and arachnoid

27
Q

What is hydrocephalus

A

accumulation of CSF in the ventricular system (obstruction/overproduction) resulting in inc ICP

28
Q

What is idiopathic intracranial HT

A

increase in ICP with no detectable cause. Symptoms include headache and visual disturbances.

29
Q

what is papilloedema

A

Optic disc swelling due to increased intracranial pressure causing pressure in the subarachnoid space surrounding the optic nerve

30
Q

where is aqueous humour produced and does it require energy?

A

energy dependent process in the ciliary body

31
Q

Flow of aqueous humour

A

Aqueous humour is produced in the ciliary body and flows into the posterior chamber of the eye. It then flows into the anterior chamber and drains into the scleral venous sinus through the canal of schlemm.

32
Q

where is the canal of schlemm

A

At the iridocorneal angle- angle between iris and cornea

33
Q

Histology of ciliary body and posterior iris

A

a forward continuation of the pigmented epithelium of the retina (layer closest to sclera) and an inner non-pigmented epithelial layer (layer closer to retina)

34
Q

Movement of Na and CL across the ciliary body in CSF production

A

Na and Cl from plasma are taken into pigmented epithelial cells and move into non-pigmented epithelial cells of the ciliary body through gap junctions and are then transported into the posterior chamber

35
Q

Normal intraocular pressure

A

17mmHg above atmospheric

36
Q

Conc of Na Cl and bicarbonate in aquaeous compared with plasma

A

Increased conc of Na and CL and decreased conc of bicarbonate in aquaeous humour compared with plasma

37
Q

What are CA inhibitors, how do they work and what diseases do they work for?

A

carbonic anhydrase inhibitors that block the production of bicarbonate so decrease the production of aquaeous humour. They are used in glaucoma.

38
Q

Examples of CA inhibitors?

A

Dorzolamide: eye drops
acetazolamide: oral admin and also targets kidney

Opthamology (6 decks)

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