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Semester 3 > Case 5 - blood supply to the brain and ischaemia > Flashcards

Case 5 - blood supply to the brain and ischaemia Flashcards

1
Q

stroke is what number in the leading cause of death tables

A

2nd leading cause of deaths worldwide

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2
Q

how much of body weight is the brain

A

2-3%

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3
Q

how much of the cardiac output does the brain receive

A

15%

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4
Q

How much of the body’s glucose and oxygen does the brain receive

A

20% of the oxygen and 25% of glucose

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5
Q

what is the furthest distance from a blood supply capillary is a neurone

A

20-30 micrometres

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6
Q

what are the two pairs of arteries that supply the brain

A

the internal carotid arteries (anterior) and the vertebral arteries (posterior)

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7
Q

the anterior cerebral artery is a branch of which artery

A

the internal carotid artery

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8
Q

what does occulsion of the anterior cerebral artery cause

A

paralysis and sensory loss in contralateral leg and perineum

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9
Q

what is the largest branch of the internal carotid artery

A

the middle cerebral artery

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10
Q

where does the middle cerebral artery pass though

A

the lateral sulcus and travels along the lateral surface of the frontal and parietal lobes

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11
Q

what is the most common site for a stroke

A

the middle cerebral artery

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12
Q

what would occlusion of the middle cerebral artery cause

A

contralateral paralysis - mostky in lower face and in the arm
general somatosensory deficits
speech deficits (aphasia) if dominant hemisphere is affected

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13
Q

where does the basilar artery run

A

forward in midline on ventral surface of the pons

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14
Q

what are the branches of the basilar artery

A

anterior inferior cerebellar, pontine and superior cerebellar

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15
Q

where does the basilar artery divide nd what does it divide into

A

at rostral end of the midbrain and the posterior cerebral arteries

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16
Q

what happens if there is occlusion of the basilar artery

A

coma - followed by death due to respiratory failure

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17
Q

where does the posterior cerebral artery run

A

curves around. the midbrain and reaches medial surface of the cerebral hemisphere

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18
Q

what are the important branches of the posterior cerebral artery

A

cortical branches supply the visual cortex, posterior chroiodal and posterior communicating

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19
Q

what does occlusion of the posterior cerebral artery lead to

A

blindness

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20
Q

what does the circle of willis form

A

an anastomoses

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21
Q

why are anastomoses not sufficient

A

due to narrowing of large vessels and communicating arteries because of vascular disease

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22
Q

functional consequences of stroke diagram

A
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23
Q

what are the series of events in an ischaemic stroke

A
  • lack of blood supply
  • energy failure - no ATP made
  • anoxic depolarisation of cell membranes, excitotoxicity, oxisdative stress, necrosis
  • peri-infarct depolarisation, calcium overload, mitochondrial damage
  • inflammation and programmed cell death
24
Q

progression of an intracerebral haemorrhage

A
  • rupture of a blood vessel
  • blood leaking into the brain causes disruption to the tissue, physically will displace tissue in the Brin
  • increase in inter cranial pressure
  • reduce blood flow - secondary ischaemia
  • midline shift in extreme causes
25
Q

what is the primary region of damage to the brain referred to as

A

the core

26
Q

what is the main characteristic of the core

A

this is where blood supply is reduced to dramatically low levels which is less than 20% of normal flow

27
Q

what is the penumbral region

A

an area with reduced blood flow, but not as severe as the core.

28
Q

how much of normal blood flow is there in the penumbral region

A

20-50% normal flow

29
Q

how do neurones behave in the penumbral region

A

they are still functionally active

30
Q

what does the core have that the penumbra does not

A

dead tissue

31
Q

penumbra characteristics

A
  • vulnerable tissue
  • surrounding regions
  • blood supply compromised but not cut off
  • cells under threat but not dead
  • potential for rescue
  • must start treatment early
  • can become core when the core expands and kills this as the core releases toxins
32
Q

what does a CT show

A

only the core and dead tissue

33
Q

what is the key, major excitatory transmitter in the brain

A

glutamate

34
Q

what does glutamate produce

A

downstream signals

35
Q

what happens if you have glucose in excess

A

it overwhelms the synapse, and glucose is taken back up unto the presynaptic terminals or by glial cells

36
Q

what happens to the process of glucose reuptake in stroke

A

this process is overwhelmed because of the loss of energy and the glutamate builds up and it spills over and begins to activate other types of glutamate subtype receptors which lead to cell death though downstream mechanisms

37
Q

what happens when there is a collapse of membrane patents

A

release of degenerative oxidative stress

38
Q

what is degenerative oxidative stress driven by

A

changes in the mitochondria

39
Q

what happens in oxidative stress

A

the mitochondria membranes will collapse
this will release free radicals and reactive oxygen species e.g hydrogen peroxide
this is then acted upon by free radicals such as superoxide
these free radicals which are extremely toxic, will lead to changes within the cell which leads to oxidation of proteins, perioxidation of lipids and cell death

40
Q

what drives inflammation

A

oxidative stress

41
Q

what is the term used to describe the relationship between coagulation cascades and inflammation processes

A

thrombi-inflammation

42
Q

what happens when the tight junctions in the brain are broken down

A

there will be exposure of the underlying basement membrane. this leads to the release of Von Willibrand factor which will bind platelets, these platelets will then bind fibrin and neutrophils and will form a clot in the vessel itself

43
Q

what are released by dying neurones

A

damage associated molecular patterns

44
Q

what happens to these DAMPs

A

these are recognised by the microglia, innate lymphocytes and infiltrated myeloid cells

45
Q

what does this cause s

A

stero-inflammation

46
Q

what does stero-inflammation lead to

A

leads to the up regulation and productions of chemokine and cytokines e.g IL-1B
pro-inflammatory lymphocytes and anti inflammatory lymphocytes are thought to both contrubre to dementia

47
Q

characteristics of IL-1

A
  • pro inflammatory cytokine
  • neonatal onset- multisystem inflammatory disease
  • rheumatoid arthertiiss
  • released by brain cells in response to injury
  • 2 ligands - alpha and beta
  • both released as precursor molecules
48
Q

what is anakinra

A

an IL-1 receptor antagonist that blocks the biologic activity of IL1. it is naturally occurring

49
Q

what are the two processes in recovery of stroke in the brain

A

neurogenesis and angiogenesis

50
Q

what is brain plasticity

A

when other areas adopt or take over the function that wasn’t done before

51
Q

why is inflammation important

A

stem cells release inflammatory substances

52
Q

what are the three brain/nerve stimulations

A
  • directly
  • transcranial
  • vagus nerve stimulation
53
Q

what are the problems with tPA

A

currently only a small proportion of patients treated as need to be given early and stroke services need to be optimal for this to happen

there is an increased risk of haemorrhage

incomplete re-canalisation and high (27%) re occlusion rate

repercussion itself can be detrimental as results in infammatio and oxidative stress

54
Q

percentage of stroke patients treated in the UK

A

12%

55
Q

what is the initial event in a stroke

A

excitotoxic insult resulting in a necrotic core infarct

followed by inflammatory and oxidative events leading to delayed, penumbral cell death

56
Q

what are the 3 regenerative processes

A

plasticity, angiogenesis, neurogenesis

Semester 3 (94 decks)

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