Physiology Flashcards
what is cerebrospinal fluid produced by
secretory epithelium of the choroid plexus in the cerebral ventricles
where is choroid plexus found in the adult brain
3rd, 4th and lateral ventricles
how much CSF is produced and absorbed everyday
500-600ml
where does CSF go after it’s formed in the ventricles
circulates in the subarachnoid space then absorbed into venous circulation
what does CSF do
- flows in and around the brain and spinal
cord to help cushion them from injury - supplies water, amino acids, ions
- removes metabolites
how is CSF analysis obtained
lumbar puncture
embryonic neural canal gives rise to what adult structures
- the brain’s ventricles
- the spinal cord’s central canal
what does the choroid plexus develop from
cells in the walls of the ventricles
what is an ependymal cell
type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord.
CSF secretion involves the transport of which ions across the epithelium from blood to CSF
Na+
Cl-
HCO3-
is [K+], [glucose], and [protein] higher in CSF or blood plasma
higher in blood
is [Na+] and [Cl-] higher in CSF or blood plasma
higher in CSF
CSF flows from lateral to third ventricle through two narrow openings called the ___________ _______________
interventricular foramina
journey route of the CNF
- lateral ventricles
- third ventricle
- fourth ventricle
- subarachnoid space
- arachnoid villi of dural venous sinsuses
- venous blood –> heart and lungs
what is the subarachnoid space
the cerebrospinal fluid-filled area between the arachnoid layer and the pia mater. It is part of the meningeal linings that separate the brain from the skull.
what is the main obstacle for drug delivery to the CNS
blood brain barrier
pathologies of the ventricles, choroid plexus and CSF
- tumours
- ventricular haemorrhage
- hydrocephalus
- idiopathic intracranial hypertension/ pseudotumor cerebri
what is a colloid cyst
benign growth usually located in the third ventricle and at or near the interventricular foramen
what is a epidural haematoma
arterial bleed between skull and dura
what is a subdural haematoma
venous bleed between dura and arachnoid
what is hydrocephalus
accumulation of CSF in the ventricular system or around the brain
symptoms of idiopathic intracranial hypertension
headache
visual disturbances due to papilloedema
what is papilloedema
optic disc swelling due to increased intracranial pressure transmitted to the subarachnoid space surrounding the optic nerve
visual symptoms of papilloedema
enlarged blind spot
blurring of vision
visual obscurations
loss of vision
what do carbonic anhydrase inhibitors do
reduce production of aqueous humour - used to reduce ocular pressure in glaucoma
carbonic anhydrase inhibitor examples
dorzolamide - administered as eye drops, avoiding systemic effects
acetazolomide - oral administration, also targets kidney
the aqueous humour of the posterior chamber is completely replaced in how long?
30 mins
the aqueous humour of the anterior chamber is completely replaced in how long?
120 mins
vertical pathway for signal transmission (retina)
photoreceptors —> bipolar cells —-> ganglion cells
(light is going in other direction)
what do amacrine cells in the retina do
receive input from bipolar cells and project to ganglion cells, bipolar cells and other amacrine cells
what do horizontal cells of the retina do
receive input from photoreceptors and project to other photoreceptors and biopolar cells
what are the 2 types of photoreceptors
rods and cones
which photoreceptor - seeing in dim light
rods
which photoreceptor - seeing in normal daylight
cones
is there more convergence in rods or cones
rod system
