Physiology Flashcards
what does CSF look like and what is it mainly made of?
clear and colourless, mainly water
large amounts of what in the CSF can indicate pathology
protein, blood etc
where is CSF formed and by what cells
produced by choroidal cells of choroid plexus in the lateral ventricles
where is CSF absorbed intp
venous circulation
what are the 3 main functions of CSF
1) mechanical protection and shock absorption 2) homeostatic function eg pH and hormones 3) circulation and minor exchange of nutrients and waste eg supplies water, amino acids
what is CSF analysis used for and how would you obtain a sample
for diagnosis of brain, meninges and spinal cord - obtain via lumbar puncture
in embryology, what does the CNS arise from
neural canal (week 3)
in embryology, where does the choroid plexus develop from
walls of ventricles
what is the choroid plexus made of and where are they found
made of ependymal cells and capillaries - found in the 4 ventricles of the brain
what is transported in the CSF
Na, Cl and HCO3
describe the circulation of CSF (6)
formed in choroid plexus of lateral ventricles –> flows to 3rd ventricle via inter-ventricular foramina –> 4th ventricle via cerebral aqueduct –> subarachnoid space –> circulates spinal canal –> absorbed via arachnoid granulations to venous blood
what is the function of the blood brain barrier
prevent toxins and infection entering the brain
what are 3 tumours that can arise from the ventricles, choroid plexus and CSF
colloid cysts (inter-ventricular foramen) / ependymomas (ependymal cells of choroid plexus) / choroid plexus tumours
what are 3 types of haemorrhage that can occur in the ventricles, choroid plexus and CSF
epidural (between skull and dura) / subdural (venous bleed between dura and arachnoid) / subarachnoid haemorrhage
what is hydrocephalus and what does it cause
accumulation of CSF in ventricular system or around the brain - causes and increased CSF pressure and swelling
what is idiopathic inter-cranial hypertension
increased CSF pressure but no imaging of hydrocephalus
what is papilloedema
optic disc swelling transmitted to subarachnoid space around optic nerve from raised ICP
what is aqueous humour
specialised fluid in anterior chamber that provides oxygen and metabolites for vascular components of the eye
what secretes aqueous humour
epithelial later of ciliary body
what drains aqueous humour
scleral venous sinus at iridocorneal angle
what 4 things are required for vision
pattern of object what fall onto photoreceptors in retina / light regulation / energy transduction/ reception of electrical signals by brain
what is the pathway light follows from the retina to the optic nerve
hits photoreceptor –> bipolar cells –> ganglion cells –> CNII
what do does the retina convert electromagnetic radiation into
neural signals
what are the regions of the retina
outer segment, inner segment, cell body, synaptic terminal
what is the dark current channel
opens in the dark where it is more permeable to Na and causes a depolarised membrane
what happens to levels of glutamate in the eye in the light vs dark
more in dark, less in light
what is visual acuity
ability to distinguish between 2 nearby similar points
what determines visual acuity
photoreceptor spacing and refraction
what types of photoreceptors do we have
rods and 3 types of cones
what are there more of cones or rods and which are more sensitive to light
more rods which are more sensitive to light
describe rods, convergence, spacing and visual acuity
high convergence, large spacing and decreased visual acuity
describe rods ratio to ganglion
lots of rods to one ganglion
where are rods found in the retina
periphery
what are rods ‘good’ at seeing
in dim light
describe cones: convergence, density, spacing and visual acuity
low convergence, high density, small spacing and high visual acuity
describe cones ratio to ganglion
one cone to one ganglion (very detailed vision)
where are cones found in the retina
in the fovea (central retina)
what are cones ‘good at seeing’
colour
what are the 3 types of cone and what colours do they see
short wave = blue / middle wave = green / long wave = red
