physiology Flashcards
(47 cards)
describe CSF
clear, colourless liquid comprised mainly of water
what produces CSF
secretory epithelium of the choroid plexus located in the ventricles
what are the 3 main function of CSF
- Mechanical protection = acts as a shock-absorber
- Homeostatic functions = pH affects pulmonary ventilation and cerebral blood flow. Also transports hormones
- Circulation = medium for minor exchange of nutrients and waste between blood and brain
give a brief description of the circulation of CSF
circulates in the subarachnoid space before being absorbed into the venous circulation
what does the choroid plexus develop from
cells in the walls o the ventricles
where is the choroid plexus located
3rd, 4th, and lateral ventricles
what are choroid cells
specialised cells that produce CSF in an active process.
network of capillaries in the walls of ventricles
why can secretion of CSF occur
due to the polarised distribution of Na+, Cl-, and HCO3- in the apical or basement membrane of the epithelium cells
describe the circulation of CSF in detail
from the choroid plexuses of each lateral ventricle it then flows to the 3rd ventricle via the interventricular foramina. More CSF is added by the choroid plexus in the roof of the 3rd ventricles which then flows through the aqueduct of the midbrain into the 4th ventricle. Another choroid plexus on the 4th ventricle adds more CSF. The CSF then enters the subarachnoid space through 3 openings in the roof of the 4th ventricle before circulating in the central canal of the spinal cord
what is a ventricular haemorrhage
accumulation of blood in the ventricles
what is hydrocephalus
accumulation of CSF in the ventricle system or around the brain
what is papilloadema
optic disc swelling due to increased intracranial pressure transmitted to subarachnoid space surround the optic nerve
what is aqueous humor
specialised fluid that bathes the structures within he eye
what is the role of aqueous humour
provides O2 and metabolites while contains bicarb to buffer the H+ produced in the cornea and lens by anaerobic glycolysis
how and where is aqueous humour produced
produced by an energy decent process in the epithelial layer of the ciliary body
describe the circulation of aqueous humour
from the ciliary body it flows into the posterior then anterior chamber of the eye before draining to the scleral venous sinus via a trabecular meshwork and canal of schlemm
where is the canal of schlemm located
in the angle between the iris and cornea (iridocorneal angle)
how is HCO3- and H+ formed by epithelial cells
hydration of CO2 catalysed by carbonic anhydrase
what will carbonic anhydrase inhibitors produce
reduction in the production of aqueous humour
what 4 things are required for vision
- pattern of object must fall onto vision receptors
- amount of light entering eye must regulated
- light energy must be converted into electrical signals
- brain must receive and interpret signals
what are the 2 pathways inside the lamina, what are they involved in
direct = signal transmission
lateral connections = influence signal processing
what cells are involved in the direct pathway (from posterior to superior)
photoreceptors
bipolar cells
ganglion cells
what cells are involved in the lateral connections, what do they do?
horizontal cells = receive input from photoreceptors and projects to other photoreceptor and bipolar cells
amacrine cells = receive input from bipolar cells and project to ganglion, bipolar, and other amacrine cells
what do photoreceptors do
convert light to neural signals in a process known as transduction
