Blood brain barrier Flashcards Preview

Physiology and Neuroscience > Blood brain barrier > Flashcards

Flashcards in Blood brain barrier Deck (60):
1

What can brain scans reveal?

How brain function changes in response to a task, challenge or disease

2

What does fMRI stand for?

Functional Magnetic Resonance Imaging

3

What does fMRI detect?

Does not measure brain activity directly
This imaging detects signals associated with changes in cerebral blood flow

4

What does fMRI rely on?

The coupling between neuronal activation and cerebral blood flow

5

How does fMRI indirectly measure neural activity?

When neural activity in a region increases, blood flow to that region also increases

6

How active is the brain?

Most metabolically active of all organs in the body

7

How much does the brain weigh?

Roughly 2% of total body weight

8

How much cardiac output does the brain receive?

15%

9

How much body energy does the brain consume at rest?

20%

10

What does the brain not have?

Glycogen stores

11

What does the brain require because of the lack of glycogen stores?

Constant supply of glucose and O2 for ATP metabolism

12

Why does the brain use so much energy?

Communication of neurons requires a lot of energy

13

What is the main site of energy consumption?

Synapses

14

What is energy in the synapses for?

Energy is used to reverse the movement of ions at synapses during neuronal communication

15

What do synapses rely heavily on?

Local ATP synthesis

16

What is within each synapse which suggests the synapse needs a lot of energy?

Mitochondria

17

What is the ATP used to do in the synapse?

Resetting the synapse to its normal state

18

What is required to maintain synaptic activity?

Constant supply of glucose and oxygen

19

How are glucose and oxygen delivered to the brain?

Via its blood supply in cerebral circulation

20

What are the 2 sources the brain receive its blood supply from?

Arising from the dorsal aorta
o Common carotid→ internal carotid arteries
o Subclavian artery→ vertebral arteries

21

What do the right and left vertebral arteries join to form?

Single basilar artery

22

What does the basilar artery and two internal carotid arteries form?

Circle of Willis

23

Where is the Circle of Willis located?

Base of brain

24

What part is the Circle of Willis?

Arterial ring formed from basilar artery and internal carotid arteries

25

What does the Circle of Willis give rise to?

The major cerebral arteries

26

Where do pairs of left and right cerebral arteries arise from?

Circle of Willis

27

What do pairs of left and right cerebral arteries supply?

All parts of the brain

28

What happens if one of the main carotid or vertebral arteries are blocked?

The cerebral arteries can receive through blood through Circle of Willis

29

What is each cerebral hemisphere supplied by?

Three major arteries

30

What are the three major arteries that supply each cerebral hemisphere?

Anterior Cerebral Artery
Left Middle Cerebral artery
Posterior cerebral artery

31

Where does stroke usually form?

In the middle cerebral artery

32

What are symptoms of stroke related to?

Affected area

33

Where do cerebral arteries branch?

Over the brain structures
Arteries on brain surface--> Penetrating arterioles --> capillary bed

34

What do cerebral arteries give rise to?

Penetrating arterioles then capillaries

35

How vascularised is brain tissue?

Highly vascularised

36

What does functional activation by sensory stimulation lead to?

Regional increase in the glucose metabolism in corresponding cerebral structures

37

What is the relationship between glucose use in a brain region to the blood flow in that region?

Proportional

38

What is neurovascular coupling?

Changes in neural activity cause changes in local blood flow

39

What happens with neuronal activation

Neurotransmitter release
Increase ATP consumption
Increase O2 and glucose consumption

40

What happens with neurotrasmitter release and increase in O2 and glucose consumption?

Vasoactive chemical agents cause vasodilation
Increased cerebral blood flow

41

What is neurovascular coupling the basis for?

BOLD signal detected by fMRI

42

What does fMRI measure?

Scanner measures function-related changes in blood flow

43

What does fMRI indirectly measure?

Neuronal activity

44

What cells are responsible for dilation and constriction of arterioles?

Vascular smooth muscle

45

What are responsible for dilation and constriction of capillaries?

Pericytes

46

What does the blood brain barrier (BBB) restrict?

Movement of substances into and out of the brain

47

What does the term BBB refer to?

A complex of cells that separate the brain parenchyma from the luminal contents of the cerebral vasculature

48

What are the functions of the BBB?

Protects the brain from “foreign substances” in the blood that may injure the brain
Protects the brain from hormones and neurotransmitters released in the rest of the body
Maintains a constant environment for the brain to enable normal neuronal function

49

What lines the lumen of cerebral vessels?

Endothelial cells

50

what do cerebral endothelial cells have?

Tight junctions

51

What do tight junctions in endothelial cells restrict?

Free passage of substances from the blood to the brain

52

How does glucose enter the brain?

Transport carriers for glucose facilitate its entry into the brain

53

How does O2 enter the brain?

Diffuses freely from blood to brain

54

What is the first pathway across the blood-brain barrier?

Transcellular lipophillic pathway
Lipid-soluble agents

55

What is the second way across the blood brain barrier?

Transport proteins
Glucose, amino acids, nucleosides

56

What is the third way across the blood brain barrier?

Receptor mediated endocytosis
Insulin and transferrin

57

What is the last way across the blood brain barrier?

Absorptive endocytosis
Albumin, other plasma proteins

58

Do all areas if the brain have a BBB?

No

59

Where is there no BBB?

Structures in the midline of the ventricular system collectively referred to as circumventricular organs (CVOs)

60

What are some examples of CVOs?

Pituitary gland
Median eminence
Area postrema
Preoptic recess
Paraphysis
Pineal gland
Endothelium choroid plexus