General Neurophysiology

Question 1

most of the CSF is made by ___ the rest is made by whatq

Answer 1

choroid plexus

rest made by tissue that lines the ventricles and blood vessels

Question 2

2 stage process of making CSF

Answer 2

1) passive filtration of serum: plasma loses proteins and fluid filtered into space

2) HCO3, Cl, and K concentrations controlled by channels on epithelial cells
awauporins also exist

Question 3

molecules that end up in equal or near so concentrations in both plasma and CSF

Answer 3

Na+, Cl-, and HCO3

Question 4

concentration in CSF greater than plasma

Answer 4

Mg++

Co2

Question 5

concentration greater in plasma than CSF

Answer 5

K+
Ca++
protein
glucose

Question 6

absorption of CSF is proportional to _____

Answer 6

intracranial pressure

• at pressure below 68 = no absorption
• normal pressure = 112
• increased pressure causes damage to neurons

Question 7

obstructive hydrocephalus

Answer 7

obstruct ability of CSF to get to arachnoid villi

Question 8

non-obstructive hydrocephalus

Answer 8

process of absorption of CSF is impaired not the ability to get there

Question 9

how does CSF get out

Answer 9

enters arachnoid villi then the venous sinuses by bulk flow

Question 10

blood brain barrier passive diffusion molecules

Answer 10

H20, CO2, and O2

-free steroid hormones (most proteins are bound and cannot cross)

Question 11

getting energy to neurons

Answer 11

glucose is main source
-GLUT1 transporter, non insulin dependent
2 forms:
55K on capillaries
45K on astroglia

Question 12

why is the amount of glucose lower in the CSF than plasma

Answer 12

55k and 45k system can be saturated

Question 13

transporter that moves ions from CSF to blood

• expression tied to and signal from
• related to concentration of what

Answer 13

Na+/K+/2Cl-

• expression tied to endothelin 1 and 3
  
  • production tied to signal from astrocytes
  • may be related to concentration of K+ in CSF

Question 14

many drugs do cross BBB but are moved back to blood via ____ making them ineffective

Answer 14

P-glycoprotein

Question 15

BBB function

Answer 15

maintain electrolyte composition
-particularly related to K+ and Vm

protection from toxins

prevent escape of NTs

Question 16

where is an area in the brain that we want exposed to the blood and how does this occur

Answer 16

circumventricular organs

capillaries do not have tight junctions between endothelial cells

Question 17

4 regions that fall into circumventricular organ category

Answer 17

1) posterior pituitary: release hormones into blood
2) area postrema: vomiting
3 and 4) OVLT: body water/thirst/blood volume control (angiotensin)

Question 18

sympathetic innervation to cerebral circulation

Answer 18

NPY and norep
a-adrenergic receptors
leads to constriction when systemic CO/BP increases

Question 19

parasympathetic cerebral circulation

Answer 19

Ach
VIP
PHM-27

-cause vasodilation

Question 20

sensory innervation of cerebral circulation is tied to ____ and NTs released are

Answer 20

distension
Substance P
Neurokinin A
CGRP

• all cause dilation
• extremely sensitive to torsion/manipulation–>lead to pain

Question 21

what happens from a lumbar puncture and CSF loss

Answer 21

lose CSF in brain area so it is heavier and simple motion can cause pain and headache due to torsion of blood vessels

-activation of those afferents will also cause vasodilation and increased blood flow

Question 22

cerebral blood flow is under ___ control (_____ ____) dictates where in brain blood will go

Answer 22

local

oxygen consumption

Question 23

as intracranial pressure goes up venous outflow _____ leads to ___

Answer 23

is obstructed

leads to reduced arterial flow

Question 24

cerebral blood flow is strongly ____ which means what

Answer 24

autoregulated

-held constant over wide range of systemic blood pressures

Question 25

increased systemic blood pressure causes blood vessels of brain to ____ from ___

Answer 25

constrict from sympathetic stimulation

Question 26

a decrease in brain perfusion causes what

Answer 26

activate vasomotor centers and increase systemic BP

-consequence: systemic blood pressure can be driven to very high levels in order to perfuse the brain

Question 27

what might increase the intracranial pressure?

Answer 27

hydrocephalus of any variety
edema
bleeding within skull