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Neurology > Neuro 5 - Central Blood Flow Regulation and Blood-Brain Barrier > Flashcards

Neuro 5 - Central Blood Flow Regulation and Blood-Brain Barrier Flashcards

1
Q

How much oxygen is supplied to the brain per minute?

A

55ml/100g of tissue/min

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2
Q

Why is there a vast surplus of glucose delivery to the brain?

A

Because the brain can only metabolise glucose

Ketone bodies can only be metabolized if shortage of glucose

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3
Q

Blood glucose below what value will lead to a loss in consciousness?

A

2mM

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4
Q

On what levels do you get regulation of cerebral blood flow?

A

Total cerebral blood flow

localised blood flow

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5
Q

Between what range in mean arterial blood pressure can autoregulation maintain a constant cerebral blood flow?

A

60-160mmHg

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6
Q

Name one important factor to do with muscle lining arterioles that allow regulation of blood flow.

A

Myogenic Mechanism - smooth muscle surrounding arterioles is stretched, contract to maintain a constant blood flow

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7
Q

What are the two types of control of cerebral blood flow regulation?

A

Neural and Chemical

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8
Q

What are the 4 types of neural control of cerebral blood flow?

A

Sympathetic - causes vasoconstriction
Parasympathetic - facial - can cause slight vasodilation
Central cortical neurons - neurons within the brain can release neurotransmitters to cause vasoconstriction
Dopaminergic neurons - produce vasoconstriction means blood goes to other areas

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9
Q

What feature do capillaries in the brain have that allow them to contract?

A

Have pericytes which are contractile cells

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10
Q

What do the dopaminergic neurons affecting cerebral blood flow?

A

Pericytes around capillaries and smooth muscle around arterioles

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11
Q

Dopaminergic neurons cause contraction of pericytes vis which receptors?

A

aminergic and serotonergic neurons

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12
Q

Which fibres innervate the main arteries in the brain?

A

Sympathetic

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13
Q

Name some chemical factors that cause an increase in blood flow to particular tissues.

A 
carbon dioxide
NO
pH
anoxia
adenosine
K+

all vasodilators

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14
Q

How does change in pH affect blood flow?

A

the lower the pH the more the vessel vasodilates

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15
Q

Describe how carbon dioxide indirectly causes vasodilation in the cerebral vessels.

A

H+ ions can’t cross BBB but carbon dioxide can
Carbon dioxide moves into smooth muscles
reacts with water to form bicarbonate and H+ ions
H+ ions cause vasodilation

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16
Q

Describe how NO causes vasodilation.

A

Nitric oxide stimulates guanylyl cyclase
converts GTP –> cGMP
cGMP causes vasodilation

17
Q

Where is CSF produced?

A

Choroid plexus

18
Q

What name is given to parts of the brain that receive blood flow like anywhere else but do not have a blood brain barrier?

A

Circumventricular organs

19
Q

Describe the passage of CSF through the ventricular system.

A 
Lateral ventricle
3rd ventricle
cerebral aqueduct
4th ventricle
subarachnoid space
20
Q

What is the volume of CSF in a normal person?

A

80-150ml

21
Q

What is the volume of CSF produced per day?

A

450ml a day

22
Q

State the 3 functions of CSF.

A

Protection
Nutrients
Transport

23
Q

Describe the structure of the blood brain barrier?

A

capillaries in the brain have endothelial cells with very tight junctions

pericytes can also contract making it more likely for molecules to leave the capillary

24
Q

What types of molecules can cross the blood brain barrier easily?

A

Lipophillic molecules

25
Q

How do water and glucose cross the BBB?

A

WATER - aquaporin molecules

GLUCOSE - GLUT1 transporters

26
Q

Name 3 circumventricular organs.

A

Median eminance
Subfornical
Organum vasculosum

27
Q

State four components that have a lower concentration in the CSF than the plasma.

A

K+
Calcium
Amino acids
Bicarbonate

28
Q

State two components have a high concentration in the CSF than the plasma?

A

Magnesium

Chloride

29
Q

How is osmolarity different between the CSF and plasma?

A

The same

30
Q

How is pH different in the CSF compared to plasma?

A

CSF is slightly more acidic.

Neurology (19 decks)

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