Physiology of the Eye Flashcards
What are the three main functions of cerebrospinal fluid?
Mechanical protection - shock-absorbing medium that protects brain tissue
Homeostatic function - transports hormones
Circulation - medium for minor exchange of nutrients and waste products between blood and brain tissue
How is a clinical CSF analysis carried out?
Via lumbar puncture
Describe features of normal CSF.
Clear and colourless
Contains little protein
Contains little immunoglobulins
Only has 1-5 cells/ml
Which cells produce CSF?
Choroidal cells
Which ions need to be transported across the epithelium from the blood to the CSF in order for CSF to be secreted?
Sodium ions
Chloride ions
Bicarbonate ions
Hydrogen ions
Which ions are transported from the basolateral side to the apical side?
Sodium
Chloride
Is the production of CSF in the choroid plexus an active or passive process?
Active
is not directly dependent on the arterial BP
Which ventricles are connected by the Foramen of Munroe?
Lateral ventricles to third ventricle
Which ventricles are connected by the Cerebral Aqueduct of Sylvius?
Third ventricle to fourth ventricle
Which ventricles are connected by the Foramen of Magendie (median aperture) ?
Fourth ventricle to subarachnoid space
Which ventricles are connected by the Foramen of Luschka (lateral aperture) ?
Fourth ventricle to subarachnoid space
How does CSF flow to the third ventricle?
Through 2 narrow openings called the inter ventricular foramina
Which embryological structure gives rise to the adult brain’s ventricles?
Neural canal
What is the choroid plexus?
Networks of capillaries in the walls of ventricles
What is the role of the BBB?
Ensures that material between the blood and the cirulatroy system cannot exchage freely.
What is the role of the Blood-CSF-Barrier (BCSFB)?
Ensures that there is no free exchange between the blood and and the CSF.
What does the BBB consist of?
Capillary endothelium
Basal membrane
Perivascular astrocytes
Which parts of the brain do not have a BBB?
Circumventricular organs
Pineal gland
What is papilloedema?
Optic disc swelling due to increased intracranial pressure transmitted to the subarachnoid space surrounding the optic nerve.
Which structures in brain capillaries are the site of the BBB?
Endothelial cells
How can papilloedema present?
Enlarged blind spot
Blurring of vision
Visual obscurations
Loss of vision
What is the aqueous humor of the eye?
A specialised fluid that bathes the structures within the eye.
Provides oxygen and metabolites and contains bicarbonate.
What is the role of bicarbonate in the aqueous humor?
Buffers the Hydrogen ions produced in the cornea and lens by anaerobic glycolysis.
Where is aqueous humour produced?
In the endothelial layer of the ciliary body
