Trans - Blood Brain Barrier

Question 1

perivascular sheath of pia mater around brain capillaries

Answer 1

Virchow-Robin space

Question 2

intracranial veins drain into :

Answer 2

dural sinuses

Question 3

contributes to 40% of total vascular resistance in CNS

Answer 3

penetrating parenchymal arteries

Question 4

difference of capillaries inside and outside CNS

Answer 4

outside - may be fenestrated

inside - basement membrane invested by nearly continuous layer of foot processes (astrocyte extensions)

Question 5

BBB - function

Answer 5

prevent/control entry of substance into CNS

Question 6

transport system in BBB

Answer 6

facilitated diffusion

Question 7

what type of substances can pass through BBB

Answer 7

lipid-soluble

Question 8

what junctions are in BBB

Answer 8

tight junctions

Question 9

how do substances pass through the BBB

Answer 9

substances cannot pass through intracellular spaces - they need to pass through the plasma membrane of the endothelial cells by facilitated diffusion

Question 10

transport of glucose into CNS

Answer 10

through GLUT1

Question 11

[T/F] astrocytic foot processes are important components of BBB

Answer 11

F

Question 12

[T/F] BBB fully encloses all structures in the brain

Answer 12

F

Question 13

why is the BBB less developed in some areas of the brain

Answer 13

to allow the brain to monitor blood content/flow

Question 14

where is the BBB less developed?

Answer 14

1. anterior 3rd ventricle
2. tuber cenereum (hypothalamus)
3. pineal gland
4. area postrema (in 4th ventricle near obex)

Question 15

brain is __% of body weight

Answer 15

2

Question 16

brain uses up ___% of cardiac output

Answer 16

15

Question 17

normal blood flow through brain

Answer 17

50-55 ml/100g/min

~750 ml/ min

Question 18

brain uses up ___% of O2

Answer 18

20

Question 19

normal O2 consumption

Answer 19

3.7ml/100g/min

~50ml/min

Question 20

relationship of perfusion pressure and cerebral blood flow

Answer 20

direct

Question 21

relationship of total vascular resistance and cerebral blood flow

Answer 21

inverse

Question 22

principal extracerebral factor affecting CBF

Answer 22

systemic arterial BP

Question 23

normal cerebral venous pressure is relatively ____

Answer 23

low

Question 24

CBF is (1)__________ by up to (2) _____ in anemia

Answer 24

1. increased

2. 30%

Question 25

CBF is (1)___ by up to (2)___ in polycythemia

Answer 25

1. decreased | 2. 50%

Question 26

resistance to flow is (1)_____ by arterial disease, causing (2)_______ of CBF

Answer 26

1. increased | 2. decrease

Question 27

resistance to flow is (1)_____ by pathologic anastomosis, causing (2)_______ of CBF

Answer 27

1. decreased | 2. increase

Question 28

least significant mechanism of regulating intracranial pressure

Answer 28

neurogenic

Question 29

extrinsic neurogenic signals for regulating intracranial pressure

Answer 29

1. parasympathetic 2. sympathetic 3. trigeminal nerve

Question 30

intrinsic neurogenic signals for regulating intracranial pressure

Answer 30

locus ceruleus

Question 31

fastest responding mechanism for regulating intracranial pressure

Answer 31

myogenic

Question 32

most potent mechanism for regulating intracranial pressure

Answer 32

pCO2

Question 33

mechanisms by which CO2 and O2 may act in response to pressure changes

Answer 33

1. direct to muscle --> ex. supply of oxygen causes vasoconstriction 2. indirect --> stimulation of neurogenic detector mechanisms for gas concentration or pH

Question 34

acidosis will cause:

Answer 34

vasodilation

Question 35

alkalosis will cause:

Answer 35

vasoconstriction

Question 36

myogenic response to increased pressure? why?

Answer 36

vasoconstriction --> to prevent too much blood going into the brain

Question 37

myogenic response to decreased pressure? why?

Answer 37

vasodilation --> to allow more blood to perfuse brain despite low arterial pressure

Question 38

increased pCO2 causes what? why?

Answer 38

vasodilation --> increased carbon dioxide means increased metabolism. vasodilation to allow fresh blood to perfuse the tissue and carry away waste products

Question 39

decreased pCO2 causes what? why?

Answer 39

vasoconstriction --> no need to increase flow to cope with increase in metabolic byproducts

Question 40

decreased pO2 causes what? why?

Answer 40

vasodilation --> need to increase flow to perfuse the tissue

Question 41

increased pO2 causs what? why?

Answer 41

vasconstriction --> no need for increase in flow, tissue is not hypoxic

Question 42

consequences of high intracranial pressure

Answer 42

squeezing of brain tissue --> brain damage due to mechanical injury

Question 43

consequences of low intracranial pressure

Answer 43

brain damage due to hypoperfusion

Question 44

ability of an organ to maintain its internal blood flow constant for all by the widest extremes of pressure

Answer 44

autoregulation

Question 45

in what BP range does CBF autoregulation occur

Answer 45

60-150 mmHg arterial BP

Question 46

what is the maximum BP for autoregulation of CBF

Answer 46

160mmHg

Question 47

main mechanism for autoregulation in CBF

Answer 47

myogenic

Question 48

mechanism of neurogenic autoregulation of CBF

Answer 48

influence through neurotransmitters

Question 49

strongest mechanism for autoregulation ifn CBF

Answer 49

chemical-metabolic

Question 50

chemical-metabolic autoregulation of CBF involves what:

Answer 50

CO2, O2, pH

Question 51

transient increase of CBF in regions of the brain active in certain thoughts or emotions

Answer 51

metabolic coupling of CBF

Question 52

duration of metabolic coupling of CBF

Answer 52

1-2 seconds

Question 53

overall effect of metabolic coupling of CBF on total CBF

Answer 53

minimal/negligible