Blood supply Flashcards

1
Q

What % of the following does the brain use

a) Cardiac output
b) total body oxygen
c) total body glucose

A

a) 15%
b) 20%
c) 25%

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2
Q

What is average brain blood flow

A

46ml/100g/min

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3
Q

How many seconds of anoxia lead to unconciousness

A

20

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4
Q

Describe structure of arteries in the brain

A

Thin walled so easily blocked distorted or ruptured

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5
Q

Describe structure of veins in the brain

A

Thin walled so no muscles or elasticity to help return

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6
Q

What causes increased flow to the brain

A

Increased CO2

Reduced 02

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7
Q

What % change in CO2 is needed to double blood flow to the brain

A

70

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8
Q

Which arteries provide cerebral blood flow and in what proportion

A

80% from carotids

20% from vertebrals

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9
Q

2 common variations of the circle of willis

A

One posterior communicating small, one large

Anterior communicating large

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10
Q

What artery do striate come off and what do they supply

A

Internal capsule, lentiform nucleus etc

Come off middle cerebral

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11
Q

What artery supplies majority of lateral surface of brain

A

Middle cerebral artery

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12
Q

What does the basilar artery supply

A

Pons and cerebellum

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13
Q

What does the posterior cerebral artery supply

A

Inferior and medial aspects of temporal and occipital cortex
Thalamus and posterior internal capsule
Midbrain

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14
Q

What does the vertebral artery supply

A

Spinal cord

Dorsal medulla of brainstem (PICA)

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15
Q

Where do superficial cerebral veins cross

A

Subarachnoid space

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16
Q

What is the function of arachnoid granulations

A

Allow CSF to flow into venous blood of sinuses but prevent backflow of blood into sub arachnoid space

17
Q

Causes of ischaemic strokes

A

Atherosclerosis

Embolism

18
Q

Causes of cerebral haemorrhage

A

Trauma

Spontaneous (haemorrhagic shock)

19
Q

What happens in an MCA stroke, dominant hemisphere

A

Global aphasia

Sensorimotor loss on contralateral face, upper limb and trunk

20
Q

What happens in an MCA stroke non dominant hemisphere

A

Neglect syndrome

21
Q

What happens in a stroke that affects ACA

A

Contralateral sensorimotor loss below waist
Urinary incontinence
Personality defects

22
Q

What happens in a stroke that affects PCA

A

Contralateral homonymous hemianopsia
Reading and writing defects
Impaired memory

23
Q

What is transient ischaemic attack

A

Temporary loss of brain function <30 minutes

24
Q

What are TIA symptoms if it affects anterior circulation

A

Motor weakness
Hemi-sensory loss
Dysarthria
Transient monocular blindness

25
Q

What are TIA symptoms if it affects posterior circulation

A

Vertigo
Diplopia
Ataxia
Amnesia

26
Q

How does extra/ epi dural haematoma present?

A

May present with lucid period immediately after trauma followed by unconciousness

27
Q

Symptoms of epidural bleed (explain them)

A
  • Blood collects in compresses intracranial structures
  • Compress cranial nerve III
  • Weakness of extremities on opposite side of lesion
  • Loss of visual field opposite to the lesion
28
Q

Symptoms of subarachnoid haemotoma

A

Severe headache
Vomiting
Confusion
Lowered level of conciousness

29
Q

What can be seen on CT scan of subarachnoid haemotoma

A

White signal diffuse over sulci on both sides

30
Q

Name the 3 forms of cerebral aneurysms

A

Saccular
Fusiform
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