physiology Flashcards
what is cerebrospinal fluid produced by
the secretory epithelium of the choroid plexus of each lateral ventricle
where does CSF circulate
in the subarachnoid space
where is CSF absorbed
into venous circulation
3 functions of CSF
- mechanical protection - shock absorbing medium that protects brain tissue
- homeostatic function - pH affects pulmonary ventilation and cerebral blood flow, transports hormones
- circulation - medium for minor exchange of nutrients and wast products between blood and brain tissue
what is normal CSF like
contains little protein and little immunoglobulins
-clear and colourless
what is the choroid plexus
networks of capillaries in walls of ventricles
what ions does CSF secretion involve the transport of from basolateral to apical
Na+
Cl-
HCO3-
what are the ventricles of the brain
a communicating network of cavities filled with cerebrospinal fluid (CSF) and located within the brain parenchyma
what are the four ventricles connected by
CSF circulation
- formed in lateral ventricles
- flows to third ventricle through interventricular foramina
- more CSF added by choroid plexus in roof of third ventricle
- flows through aqueduct of midbrain
- into fourth ventricle
- another choroid plexus in fourth adds more CSF
- then enters subarachnoid space
- then circulates in central canal of spinal cord
how does CSF return to venous blood
through arachnoid granulations into superior sagittal sinus
what is blood supply ot the brain restricted by
the blood-brain barrier
what is hydrocephalus
accumulation of CSF in the ventricular system of around the brain
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 is the aqueous humour
a specialized fluid that bathes the structures within the eye
-provides oxygen and metabolites and contains bicarbonate
what does bicarbonate do
buffers the H+ produced in the cornea and lens by anaerobic glycolysis
where is aqueous humour produced
epithelial layer of ciliary body
what are the two layers of ciliary epithelium
pigmented and non-pigmented
what is the net movement of Cl- and Na+ through cells from interstitial fluid to aqueous humour accompanied by
water moving through ciliary epithelial cells water channels, aquaporins and through paracellular pathway down the osmotic gradient created by solute movement
which enzyme is responsible for the production of these ions
carbonic anhydrase
what must happen to see an object
- the pattern of the object must fall on the vision receptors (accommodation)
- the amount of light entering the eye must be regulated
- the energy from the waves of photons must be transduced into electrical signals
- the brain must receive and interpret the signals
where is superior visual field seen
lower cortex
where is right visual field seen
lower cortex
