Week 1 - Physiology Flashcards
function of the choroid plexus
makes CSF - 500-600 / day
role of CSF (4)
Supplies with water + amino acids + ions
Removes metabolites
Shock absorbing
pH controls cerebral blood flow
describe how plasma becomes CSF ?
passes through the choroid plexus “dialysis”
- ion content (Na + Cl) with water is exchanged for K and glucose
what is the foramen between lateral and 3rd ventricles?
Interventricular foramen of Monroe (into the 3rd child lol)
what foramen is between 3rd and 4th ventricles?
cerebral aqueduct
how does CSF get into the venous system after being secreted into the subarachnoid space?
into the arachnoid villi of dural venous sinuses –> into the superior sagittal sinuses –> venou system
what are the three openings out of the 4th ventricle into the subarachnoid space called?
2 x foramen of luschka (l for lateral
1 x foramen of magendie
what are 2 bonuses of the BBB?
controls the bp in the brain independently to systemic - keep more stable
protect brain from common bacterial infections + toxins
name and describe 3 layers of CNS protection from outer to inner
dura mater - thick, dense, connective tissue
arachnoid mater - delicate. folds down in the longitunidal fissure
pia mater - thin fibrous layer that encloses CSF and blood vessels
brain tumour arising from ependymal cells lining the ventricles?
ependtmomas
what is an arterial bleed between skull and dura called?
epidural hematoma
what is an venous bleed between dura and arachnoid called?
subdural hematoma
what is the difference between an epidural vs. subdural hematoma?
epidural = rapid = arterial
subdural = venous = slow
what is hydrocephalus ?
accumulating CSF causing enlargement of 1 or more ventricles and increased pressure
eye sign of hydrocephalus - why?
papilloedema
optic disc swelling due to high pressure in the subarachnoid space around the optic nerve
symptoms of papilloedema ? mild –> severe
blind spot / blurred vision / obscured / loss of vision
what makes aqueous humour?
it is formed when plasma “filters” through
what are the two parts of the ciliary epithelium?
NPE (inner) - non pigmented
PE (outer)
what 2 things are covered by PE and NPE?
ciliary body and posterior surface of the iris
how do carbonic anhydrase inhibitors inhibit production of aqueous therefore decrease ocular pressure?
stop bicarbonate ion production… so Na and Cl aren’t drawn into the cell - they normally draw in more WATER
what is dorzolamide and what is it used to treat? RoA ??
Dorzolamide is a carbonic anhydrase inhibitor used to treat increased pressure (glaucoma). Given as eye drops.
What is acetazolamide and what it is used to treat? Important S/E?
Acetazolamide is a carbonic anhydrase inhibitors which decreases ocular pressure. Given orally and can affect kidneys
light signals go straight to the back (photoreceptor cells) and then are processed more as they move forward in Vertical direct transmission. What are the next two parts of “vertical connection”?
- photoreceptors
- bipolar cell
- ganglion cells
in addition to the verticle transmission, there is addisional processing from lateral connections. What are the 2 “horizontal” cells?
- horizontal cell (between photoreceptors + bipolar)
2. amacrine cells (between bipolar and ganglion)
what is the neurotransmitter that is involved in vision? (more of it in the dark)
Gluamate !
what do you need to have good acuity? (2)
high refractive power
closely spaced photoreceptrtors
what do you need to have good sensitivity (ie see in dim lighting) ?
lots of convergence
why are rods helpful to see in the dark?
lots of convergence = good sensitivity
rods are widely spread out so give good convergence
why are cones helpful to see in the light?
in the light, less convergence is needed, and acuity is more important
cones are close together so give good acuity
where in the retina are rods more densely located?
peripheral retina
where in the retina are cones more densely located?
central retina (fovea)
what type of cones see blue
short ones = short wavelength of blue
