Cerebral vasculature and brain homeostasis

Question 1

what is the direction of water flow across a choroid plexus cell?

Answer 1

blood => ventricular lumen

Question 2

what creates the osmotic gradient carrying water from the blood to the ventricular lumen?

Answer 2

Na-K-ATPase creates electrochemical gradient for Na, which CAUSES A NET FLUX of Na, HCO3, and Cl into the ventricles

Question 3

how does Na enter the choroid plexus epithelial cells

Answer 3

Na-dependent Cl-/HCO3- exchanger (NCBE)

Question 4

what two transporters are found on the luminal side of the choroid plexus epithelial cells?

Answer 4

Na-K ATPase

aquaporin

Question 5

what ion accumulates within the choroid cell, creating a CONCENTRATION gradient

Answer 5

HCO3-

Question 6

where does the HCO3- and Cl- from within the choroid cell go?

Answer 6

into the ventricle, via apical transporters

Question 7

what ion accumulates within the choroid cell, creating AN ELECTROCHEMICAL gradient

Answer 7

Cl-

Question 8

what two values are equal in CSF and serum

Answer 8

osmolarity

Na

Question 9

is pH more acidic is the CSF or serum

Answer 9

CSF pH is more acidic (7.33)

Question 10

what two values are greater in CSF than serum

Answer 10

Cl- and CO2

Question 11

what is absorption of CSF proportional to

Answer 11

intracranial pressure (ICP)

Question 12

at what ICP does absorption of CSF STOP

Answer 12

<68 mm

Question 13

what structure absorbs CSF vis what mechanism

Answer 13

arachnoid villi via bulk flow

Question 14

increasing levels of WHAT in the blood increases cerebral blood flow?

Answer 14

CO2

Question 15

why do people have headaches after LPs

Answer 15

decreased CSF volume => break is heavier => blood vessels are more easily agitated => PAIN

Question 16

how does intracranial pressure influence cerebral blood flow

Answer 16

increased ICP osbstructs venous outflow => reduced arterial flow

Question 17

does SNS or PNS mediate autoregulation of blood flow

Answer 17

SNS!

Question 18

when BP is high, what does the SNS do to systemic vasculature

Answer 18

VASOCONSTRICT

protects capillaries and BBB

Question 19

how is systemic BP altered in the event of reduced brain perfusion

Answer 19

activation of vasomotor centers => INCREASE BP

Question 20

what are circumventricular organs

Answer 20

organs which lack BBB

Question 21

what substances passively diffuse across the BBB

Answer 21

water
nonpolar substances
CO2
O2

Question 22

what are the three cellular constituents of the BBB

Answer 22

astrocyte endfeet
pericytes
capillary endothelial cells

Question 23

how does glucose enter the brain

Answer 23

GLUT1

Question 24

is GLUT1 insulin dependent?

Answer 24

no

Question 25

what is the function of p-glycoprotein in the BBB

Answer 25

moves drugs that were able to cross the BBB back into the blood

Question 26

how is Na-K-2Cl transporter expression regulated

Answer 26

astrocyte signals => endothelin 1 and 3 => increased expression

Question 27

what glucose transporter is found on neurons

Answer 27

GLUT 3

Question 28

what glucose transporter is found on microglia

Answer 28

GLUT 5

Question 29

what are the four circumventricular organs

Answer 29

posterior pituitary
area postrema
OVLT
subfornical organ

Question 30

what is the function of area postrema?

Answer 30

initiation of vomiting

Question 31

what is the function of OVLT (orgnum vasculosum of the lamina terminalis)

Answer 31

TARGET OF ANGIOTENSIN II

regulation of total body water, thirst