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Flashcards in General Neurophysiology Deck (27)
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1
Q

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

A

choroid plexus

rest made by tissue that lines the ventricles and blood vessels

2
Q

2 stage process of making CSF

A

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

3
Q

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

A

Na+, Cl-, and HCO3

4
Q

concentration in CSF greater than plasma

A

Mg++

Co2

5
Q

concentration greater in plasma than CSF

A

K+
Ca++
protein
glucose

6
Q

absorption of CSF is proportional to _____

A

intracranial pressure

  • at pressure below 68 = no absorption
  • normal pressure = 112
  • increased pressure causes damage to neurons
7
Q

obstructive hydrocephalus

A

obstruct ability of CSF to get to arachnoid villi

8
Q

non-obstructive hydrocephalus

A

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

9
Q

how does CSF get out

A

enters arachnoid villi then the venous sinuses by bulk flow

10
Q

blood brain barrier passive diffusion molecules

A

H20, CO2, and O2

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

11
Q

getting energy to neurons

A
glucose is main source
-GLUT1 transporter, non insulin dependent
2 forms:
55K on capillaries
45K on astroglia
12
Q

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

A

55k and 45k system can be saturated

13
Q

transporter that moves ions from CSF to blood

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

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
14
Q

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

A

P-glycoprotein

15
Q

BBB function

A

maintain electrolyte composition
-particularly related to K+ and Vm

protection from toxins

prevent escape of NTs

16
Q

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

A

circumventricular organs

capillaries do not have tight junctions between endothelial cells

17
Q

4 regions that fall into circumventricular organ category

A

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

18
Q

sympathetic innervation to cerebral circulation

A

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

19
Q

parasympathetic cerebral circulation

A

Ach
VIP
PHM-27

-cause vasodilation

20
Q

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

A

distension
Substance P
Neurokinin A
CGRP

  • all cause dilation
  • extremely sensitive to torsion/manipulation–>lead to pain
21
Q

what happens from a lumbar puncture and CSF loss

A

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

22
Q

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

A

local

oxygen consumption

23
Q

as intracranial pressure goes up venous outflow _____ leads to ___

A

is obstructed

leads to reduced arterial flow

24
Q

cerebral blood flow is strongly ____ which means what

A

autoregulated

-held constant over wide range of systemic blood pressures

25
Q

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

A

constrict from sympathetic stimulation

26
Q

a decrease in brain perfusion causes what

A

activate vasomotor centers and increase systemic BP

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

27
Q

what might increase the intracranial pressure?

A

hydrocephalus of any variety
edema
bleeding within skull