General Neurophysiology

Question 1

______ tissue makes Cerebrospinal Fluid?

Answer 1

Choroid Plexus (makes about 50-70% 0f the CSF)
remaining CSF is made by the tissue that lines the ventricles and blood vessels

Question 2

What are the two stages of making CSF?

Answer 2

Step 1: passive filtration of serum

Step 2: HCO3, CL, and K concentrations controlled by channels on epithelial cells, aquaporins also exits

Question 3

T/F Production of CSF is constant over a wide range of intracranial pressures?

Answer 3

True

Question 4

_____, ______, and ______ are equal or nearly equal in the CSF and plasma?

Answer 4

Na+, Cl-, and HCO3

Question 5

_____ and _____ are in greater concentrations in the CSF than the plasma?

Answer 5

Mg2+ and CO2

Question 6

_____, ______,_____, and ______ are in lesser concentration in the CSF than the plasma?

Answer 6

K+, Ca2+, protein, and Glucose

Question 7

T/F CSF is recirculated.

Answer 7

False

make about 550 ml/day

Question 8

What does CFS flow through?

Answer 8

ventricles, through the different foramen

Question 9

Absorption of CSF is performed by ______ ____?

Answer 9

arachnoid villi
endothelium of sinus and the membrane on the villu have fuse; bulk flow of CFS into venous sinus is primary, pinocytosis also documented

( w/ aging the fusion of the membrane increases thus the CSF bulk flow decreasing therefore increase CFS

Question 10

Absorption of CFS is proportional to _____ _______?

Answer 10

intracranial pressure

• at pressure below 68mm CSF, no absorption
• increased pressure causes damage to neurons

Question 11

What is the role of the CSF?

Answer 11

to protect the brain (weight in air: 1400g; weight in CSF; 50 g; effect of CSF: priceless)

Question 12

_______ and _______ are the two components in the capillaries that limit exchange

Answer 12

tight junctions b/w endothelial cells and glial endfeet come in close contact with blood vessel

Question 13

_______, ________, _______, and _________ passively diffuse across the brain barrier.

Answer 13

H20, CO2, O2, free steroid hormone (most are protein bound)
lipid soluble molecule may cross

Question 14

What is the major energy source for neurons?

Answer 14

glucose (does not cross the blood barrier readily)

Question 15

How does the glucose get transport into the brain?

Answer 15

GLUT 1 transporter (not insulin-dependent) 
Two forms (45 and 55 K): 55K on capillaries, 45K on astroglia

Question 16

What transporter moves all those ions from CSF to blood?

Answer 16

Na/K/2Cl transport, expression tied to endothelin 1 and 3

Question 17

ET production tied to a signal from the ______?

Answer 17

astrocytes

may be related to [K+] CSF

Question 18

___________ transports move drugs back across the BBB?

Answer 18

p-glycoproteins (type of MDR-1: protects the compositions of the CSF)

Question 19

What is the function of the BBB?

Answer 19

protect the chemical composition of the CSF from blood-borne agents
maintain electrolyte composition (K= and membrane potentials)
protection from toxins
prevent escape of neurotransmitters

Question 20

_______ are places where the brain is exposed to the blood?

Answer 20

Circumventricular junctions (capillary dont have tight junctions; allowing for paracellular transport)

Question 21

What are the 4 circumventricular junctions?

Answer 21

The posterior pituitary ( neurohpophysis, release hormones into blood)
Area Postrema ( aka chemoattrackant tigger center) causing vomiting reflex to blood-borne pathogens
Organum vasculosum of the lamina terminalis (OVLT)
Subfornical organ (both control of body water/thirst/blood volume)

Question 22

Describe the sympathetic innervation of the Cerebral Circulation.

Answer 22

neurotransmitters: norepi, and NPY
receptors: alpha-adrenergics (vasoconstriction)
fires only when systemic BP is toooo high to protect the brains

Question 23

Describe the parasympathetic innervation of the cerebral Circulation.

Answer 23

Larger blood vessels
Ach and vasoactive intestinal polypeptide (VIP) and PHM-27
cause vasodilation

Question 24

Describe the sensory innervation of the cerebral circulation

Answer 24

sensory innervation to the distal blood vessels

Neurotransmitters: Substance P, nerokinin A, and CGRP (all cause dilation)

Question 25

The brain will be effectively ______ in the presence of reduced CSF volume.

Answer 25

heavier

may cause pain b/c of the torsion of the blood vessels

Question 26

Cerebral blood flow is under _______ control; _______ _____ dictates where in the brain the blood will go

Answer 26

local
Oxygen consumption (depended on NO)

Question 27

As intracreanial pressure increases; venous outflow _______?

Answer 27

decreases (is obstructed) resulting in reduced arterial flow

Question 28

High blood pressure causes the ________ in the brain to _______ the vasculature

Answer 28

sympathetics to vasoconstrict (this protects the capillaries in the brain from damage

Question 29

A _____ in brain perfusion will activate the vasomotor center and increase systemic BP

Answer 29

decrease

Question 30

3 cause of increased intracranial pressure?

Answer 30

hydrocephalus of any variety
edema
bleeding within the skull