Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

eLCRS - 뉴로 > Neuro 5: Regulation of blood flow + Blood Brain Barrier > Flashcards

Neuro 5: Regulation of blood flow + Blood Brain Barrier Flashcards

1
Q

Give values of blood flow to the brain.

A

high at 55ml/100g tissue/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

__ seconds of CBF interruption = unconsciousness

A

4 seconds of CBF interruption = unconsciousness

after few mins –> irreversible damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are some causes of syncope?

A
  • reduced blood supply to the brain
  • low BP
  • postural changes
  • vasovagal attack
  • sudden pain
  • emotional shock
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is supply of glucose vital to the brain?

A
  • because the brain can’t store, synthesis, or utilize any other source of energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

other than glucose, but is the other source of energy?

A
  • ketones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to brain function in HYPOglycaemia?

A
  • if glucose conc <2mM

- can result in unconsciousness, coma, + death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are some symptoms of HYPOglycaemia ?

A
  • disoriented, slurred speech, impaired motor function.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the range for normal fasting levels?

A

4-6 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is the 2 mechanisms by which cerebral blood flow regulated ?

A
  1. mechanism affecting total cerebral blood flow

2. mechanisms that relate activity to requirement in specific brain regions through altering localized blood flow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is total cerebral blood flow auto regulated?

A
  • autoregulation occurs over MABP 60-160 mmHg
  • through myogenic response
  • Increase in vessel wall pressure –> causes smooth muscle contraction
    (decreasing cerebral blood flow)
  • stretch sensitive cerebral vascular smooth muscle CONTRACTS at HIGH BP
    RELAXES at LOW BP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Below the autoregulatory pressure range, what happens to the brain?

A
  • leads to compromised brain function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Above the autoregulatory pressure range, what happens to the brain?

A
  • increased blood flow –> causes swelling of brain tissue

- causes increase in intracranial pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

local brain activity determines O2 + glucose demand –> so local changes in blood supply =

A

local auto regulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 methods of local regulation of CBF ?

A
  • neural control

- chemical control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 4 neural factors that regulates CBF

A

a) Sympathetic Nerve Stimulation to main cerebral arteries –> causing vasoconstriction

b) Parasympathetic Stimulation
- -> causes slight vasodilation

c) Central Cortical Neurones –> releases a variety of vasoconstrictor neurotransmitters (e.g catecholamines)
d) Dopaminergic Neurones –> produces vasoconstriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does dopaminergic neurones help with regulation of CBF?

A
  • they innervate penetrating arterioles + pericytes around capillaries
  • and they participate in the diversion of cerebral blood –> to areas of high activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Dopamine causes contraction of pericytes via _______ and _____ receptors

A

Dopamine causes contraction of pericytes via aminergic and serotoninergic receptors

18
Q

The main arteries of the brain = innervated by

A

sympathetic fibres

19
Q

note: CNS = densely vascularized.

No neurone = more than 100um from a capillary

A

-

20
Q

List examples of chemical factors that regulates CBF

A
  • CO2
  • PH
  • Nitric Oxide
  • K+
  • Adenosine
  • Anoxia
    (vasodilators)
21
Q

Describe the graph

for the effect of pCO2 on Cerebral Blood Flow

A

CO2 has strong effect on cerebral blood flow

- sharp rise

22
Q

Describe the mechanism of cerebral arterial vasodilation by CO2

A
  • H+ ions can’t cross the BBB
    BUT
  • H+ ions can be generated in the brain
  • so CO2 can move through the BBB
  • in smooth muscle cells + neural tissue: CO2 + H2O —> HCO3- + H+ (in presence of Carbonic anhydrase)
  • so H+ produced –> PH decreases –> acts as vasodilator –> causes relaxation of smooth muscle cells –> causes increase in Blood Flow
23
Q

How is CSF produced?

A
  • CSF = produced by the choroid plexus
  • capillaries are surrounded by ependymal cells (tight junctions)
  • ependymal cells secrete molecules into the ventricles
  • to make CSF
24
Q

The ventricles, aqueducts + canals of brain = lined with ________ cells

A

The ventricles, aqueducts + canals of brain = lined with ependymal cells

25
Q

What are circumventricular organs ?

A
  • structures in the brain that receive blood flow as usual BUT doesn’t have BBB
  • they have fenestrated capillaries
  • so it lies OUTSIDE the BBB
26
Q

Describe the path of CSF

A
  • lateral ventricles
  • 3rd ventricle
  • cerebral aqueduct
  • 4th ventricle
  • subarachnoid space
27
Q

What is the volume of CSF?

What is volume of CSF formed per day?

A

Volume of CSF = 80 - 150 ml

Volume of CSF formed per day = 450 ml/day

28
Q

What are 3 functions of CSF?

A
  • physical protection
  • nutrition of neurones
  • transport of molecules
29
Q

How does the composition of plasma + CSF differ?

A

CSF has :

  • less protein
  • less K+
  • less CO3-
  • less Ca2+
  • more Mg2+
  • more Cl-

PH = slightly more acidic

30
Q

CSF has less protein.

Why is this important clinically?

A

when extracting CSF

presence of protein in CSF –> indicative of an issue

31
Q

compare differences between peripheral + BBB capillaries.

A

PERIPHERAL capillaries:
- has SPARSE pericyte coverage

BBB capillaries:

  • has DENSE pedicure coverage
  • covered with “endfeet” from astrocytes
32
Q

Why does BBB capillary have very tight junctions?

A
  • allows BBB to control exchange of substance through memb transporters
  • Blood-borne infectious agents –> have reduced entry into CNS tissue
33
Q

What type of molecules can cross BBB relatively easily (e.g alcohol + anesthetics)

how?

A
  • lipophilic molecules

- through diffusion down conc gradients

34
Q

Give examples of 3 Circumventricular organs (CVO)

A
  • Median eminence region of hypothalamus
  • subfornical organ (SFO)
  • OVLT
35
Q

Antihistamines + BBB

A

old histamines could cross BBB

anthistamines make you drowsy

nowadays, antihistamines can’t cross BBB
–> so you feel less drowsy

36
Q

What are pericytes?

A

cells that wrap around capillaries

37
Q

what is the purpose of the capillaries in choroid plexus being leaky
but cells around them having tight junction ?

A
  • allows control of production of CSF
38
Q

What is the normal volume of CSF

A
  • around 80 - 150 ml
39
Q

What types of molecules can’t usually cross the BBB?

A

amino acids, glucose, toxins etc.

40
Q

How does glucose enter CSF –> and eventually the brain?

A

via GLUT 1 transporter

41
Q

When might BBB break down?

A
  • inflammation
  • trauma
  • infection
  • stroke
42
Q

Describe how manipulation of the BBB allows treatment for Parkinson’s Disease .

A

treatment for parkinson = raise levels of dopamine in brain
- dopamine can’t cross BBB
but
L-DOPA CAN via an amino acid transporter

–> a.acid transporter thinks L DOPA is an amino acid
and is converted to dopamine in the brain

but LDOPA is converted to dopamine peripherally so
carbidopa is coadministered with L DOPA
so now L DOPA isn’t converted to dopamine OUTSIDE of the brain

eLCRS - 뉴로 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions