Flashcards in Module B-07 Deck (54)
Which are the 3 extracellular fluid compartments and the volume of each?
Where is majority of fluid of body found ?
Where is CSF found?
2)Subarachnoid space (67-117 ml)
volume of CSF
4 functions of CSF
1) Maintains Extracellular environment
2)Removes metabolites from CNS
3)regulated cerebral blood flow and pulomonary ventilation
How does CSF influence cerebral blood flow and pulmonary ventilation?
Owing to changes in its pH
What is present in high levels in CSF compared to plasma?
Cl-, Mg++ and Na+ (only slightly higher)
What is present in low levels in CSF compared to palsma
protein, glucose, K+ ,Ca++
At what levels is lumbar puncture done
L3/L4 or L4/L5
What is relevance of a lumbar puncture?
1) analysis of CSF
2) measurement of intracranial pressure
4 adverse effects of Elevated intracranial pressure (ICP)
3) Systemic hypertension
What does the Monroe-Kellie Doctrine state?
An increase in volume of one component (e.g., brain, blood, or cerebrospinal fluid) will elevate pressure (ICP) or decrease the volume of one of the other elements.
What are the 3 components of the Blood Brain Barrier
3)Capillary basement membranes
What are 2 characteristics of capillaries of the brain
lack fenestrations and have tight junctions to prevent paracellular flow (only Transcellular flow takes place)
What can pass through the BBB?
Small hydrophobic molecules, blood gases, small uncharged polar molecules,urea and glycerol
The higher the Oil/water partition coefficient the ____ (less/more) effective the transfer of the solute across the BBB
What are 2 substances moved by facilitated diffusion across the BBB
L-DOPA and Glucose
Ratio of solubility in oil versus water predicts
transcellular transfer of solutes into CNS
What transporter is used in BBB endothelial cells for glucose transport?
What transporter is used in BBB endothelial cells for L-DOPA transport?
Neutral amino acid carrier
How does glycine cross the BBB (brain to blood)
Na+-dependent cotransporter ( secondary active transport)
What can cause the tight junctions of BBB to become leaky?
1)Hypertension (high blood pressure)
3) Trauma, ischemia, inflammation or pressure
How does hyperosmolarity cause leaky endothelium
hypertonic infusions shrink endothelial cells and disable tight junction but this is reversible
Clinical use of hyperosmolarity with BBB
may permit delivery of lipid-insoluble drugs to
What differs circumventricular organs from rest of CNS
lack tight junctions in capillaries and thus lack
Name the Circumventricular organs
2) Median eminence
6) Subcommissural organ
What cells line the ventricles
Ependymal cells (group1)
What cells form the choroid plexuses?
Secretory Ependymal cells (group 2 )
where does CSF circulate?
the ventricles, the spinal canal and the entire