Module B-07 Flashcards
Which are the 3 extracellular fluid compartments and the volume of each?
1) Plasma
2) Interstitial fluid
3) CSF
Where is majority of fluid of body found ?
Intracellular 60%
Where is CSF found?
1) Intraventricular (23ml)
2) Subarachnoid space (67-117 ml)
volume of CSF
90-140ml
4 functions of CSF
1) Maintains Extracellular environment
2) Removes metabolites from CNS
3) regulated cerebral blood flow and pulomonary ventilation
4) Cushions brain
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)
1) Nausea
2) Bradycardia
3) Systemic hypertension
4) Papilledema
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
1) Endothelial cells,
2) Astrocytic endfeet
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
more
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?
GLUT-1
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)