Cerebral Vasculature and Brain Homeostasis Flashcards
Where is the Na/K ATPase located in the choroid plexus?
Apical side
Where is NCBE located in brain?
Basolateral
What is the purpose of the NCBE and Na/K atpase?
Creates transmembrane gradient that pulls water into the ventricle
What happens with Cl?
Accumulates intracellularly, forming an electrochemical gradient, then leaves cell through apically located chloride channels.
What is the overall movement of ions?
Na, Cl and HCO3 moves from blood into ventricles. Water fluxes through AQP.
What is the Na osmolarity between CSF and Serum?
Similar
CSF has a greater concentration of what compared to Serum?
Cl, CO2, H
Serum has a greater concentration of what compared to CSF?
Protein, Glucose, OH, K, Ca, Mg, HCO3.
Where is CSF reabsorbed?
arachnoid villi and pinocytosis
What is the pressure needed for absorption to occur?
Greater than 68 mm
What regulates CBF?
CO2 regulation, H+ concentration, O2 concentration and Astrocyte metabolites
What are the sympathetic neurotransmitters?
NE and NPY, alpha adrenergic receptors
What are the parasympathetic neurotransmitters?
Ach, VIP, CGRP, SP
What do sympathetics do to CBF?
Vasoconstriction when systemic CO and BP increases
Whath do parasympathetics do to CBF?
Leads to vasodilation when systemic cardiac output/BP decreases
What are the neurotransmitters of cerebral circulation?
SP, NKA, CGRP
How does ICP affect CBF?
Increased ICP decreases CBF
What is the purpose of vasoconstriction?
protects BBB and capillaries
What happens during reduced brain perfusion?
Vasomotor centers activates, systemic BP increases, blood goes to brain.
What does anemia do to CBF?
Increases
What does polycythemia do to CBF?
decreases it
What does high Pa CO2 do to CBF?
Increases it
What does very low Pa O2 do to CBF?
Increases CBF
What are the effects of acidosis on CBF?
Increases CBF
Effects of alkalosis on CBF?
Decreases CBF
Function of BBB
Maintains CSF electrolyte composition, excludes toxins, and contains neurotransmitters
Components of BBB
tight junctions, endothelial cells, basement membrane and Endfoots of Astrocytes, pericytes
What is the major energy source for the brain?
glucose
How does glucose cross the BBB?
transport proteins
Function of P-glycoprotein?
Move drugs that don’t belong that crossed BBB back into blood
Function of Na K 2Cl
transports ions from csf to blood
Function of GlutI
transports glucose from blood
Is Glut I insulin dependent or independent
insulin dependent
What is Na K 2 Cl expression tied to?
endothelin 1 and 3
What is endothelin production tied to with Na K 2 Cl?
Astrocyte signals and possibly K in CSF
Glut 3 is found on what cell?
Neurons
Glut 5 is found on what cells?
Microglia
Glut I 45 kd is found on what cells?
Astrocytes
GlutI 55 kD is found on what cells?
microvessels, choroid plexus, ependymal cells
What are the four circumventricular organs?
posterior pituitary, area postrema, organum vasculosum of the lamina terminalis, subfornical organ
Function of posterior pituitary
secretory, endocrine
Function of area postrema
sensory initiation of vomiting in response to chemotactic triggers
function of OVLT
sensory; regulation of total body water and thirst, target of Angiotensin II
Function of subfornical organ
sensory
