Structure and Function - Week 1 Blood Supply to the Brain Flashcards

1
Q

What are the properties of the brain (2)

A

High metabolic demand:
- Consumes 20% of total energy supply

Body mass
- Brain – 2% of the body mass

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2
Q

Why is blood supply important to the brain? (3)

A

Neurons don’t store glucose
Loss of blood flow
- 10 sec = Loss of consciousness
- 20 sec = cessation of electrical activity
- 4-8 min = neuronal death

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3
Q

Describe cerebral blood flow and metabolism (4)

A

50ml/100gm/min on avg

Grey matter higher, white matter lower

CBF determined by balance between arterial blood pressure and intracranial pressure

Hypothermia is neuroprotective – better neurological recovery

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4
Q

Describe the basic circuit (5)

A

Aorta —> Arteries —> Arterioles —> Capillaries —> Venules —> Veins —> Vena cava —> Right atrium —> Right ventricle —> Pulmonary artery —> Lung capillary bed —> Pulmonary vein —> Left atrium —> Left ventricle —> Aorta

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5
Q

Which arteries arise from the aortic arch? (2)

A

Left and right subclavian artery

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6
Q

Which artery supplies blood to the brain? (1)

A

Internal carotid artery

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7
Q

How do the arteries enter the brain? (1)

A

Through carotid canal

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7
Q

What does the external carotid artery supply? (1)

A

Face muscles

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8
Q

What is the carotid sinus? (4)

A

Area of bifuraction of external and internal carotid artery
Slight bulge
Has special cells in wall of artery
Senses blood pressure and any changes in blood pressure will trigger feedback loops to return blood pressure back to normal

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9
Q

Which artery supplies to the posterior brain? (1)

A

Basilar artery

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10
Q

What are the basilar artery branches? (2)

A

Anterior inferior cerebellar arteries (AICA)
Superior cerebellar arteries (SCA)
Pontine arteries

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11
Q

What are the branches of vertebral artery? (3)

A

Anterior spinal arteries (ASA)
Posterior spinal arteries (PSA)
Posterior inferior cerebellar arteries (PICA)

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12
Q

What joins the internal carotid and basilar arteries? (1)

A

Circle of Willis

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13
Q

Anterior circulation is fed by what? (1)

A

Carotid artery

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14
Q

Posterior circulation is fed by what? (1)

A

Basilar artery

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15
Q

What happens if there is a blockage in an artery (occlusion)? (2)

A

Quality of pressure changes

The other circulation compensates for the the other to maintain blood supply to the brain (posterior compensates for anterior or anterior compensates for posterior)

15
Q

Why is there an equality of pressure ? (1)

A

No mixing of anterior and posterior circulations

16
Q

What happens if there is an occlusion in the circle of willis? (1)

A

Stops blood supply to the brain

17
Q

Describe venous outflow (4)

A

Deep veins > superficial veins > venous sinuses > jugular

18
Q

How do veins leave the brain? (1)

A

Through internal jugular vein

19
Q

What happens if the internal jugular vein is blocked? (2)

A

Start to choke a person/the blood supply
Can stop inflow of air into the lungs

20
Q

What are the large veins called? (1)

A

Sinus

21
Q

Describe anterior cerebral artery (5)

A

Smaller branch
Arises at right angles from internal carotid artery
Sits on medial surface of the brain
Supplies majority of corpus callosum

22
Q

Middle cerebral artery (3)

A

Lateral surface of the brain
75-80% of blood of anterior circulation
Individual differences in parietal supply

23
Q

Posterial cerebral artery (3)

A

Medial and inferior surface of temporal lobe
Occipital
1/5th of corpus callosum (posterior)

24
Q

Supply to deep structures (3)

A

Perforating arteries
All three arteries give off deep branches
Right angles to main branch

25
Q

What are watershed zones? (3)

A

Territories at the border of 2 supply zones
Lowest blood supply
Vulnerable to ischemia or hypoxia

26
Q

Why is there a blood brain barrier? (1)

A

Neurons require stable environment

27
Q

What are the three types of fluids in the brain? (6)

A

Blood - carried into the brain through arterial system
Cerebrospinal fluid - nourishing fluid that fills the ventricles of the brain and between the membranes
Interstitial fluid - neural cells float around in this

28
Q

What is the neuromuscular unit? (3)

A

Muscles cells surrounding the arterioles are very closely packed - tight junctions
Forms the blood brain barrier

29
Q

What are tight junctions responsible for? (1)

A

Responsible for implementing rules of entry for substances from the blood into interstitial fluid

30
Q

What is the cerebrospinal fluid (3)

A

Carries nutritious molecules required for upkeep of neuronal tissue
Generated in choroid plexus
Absorbed back into the system

31
Q

Rules of entry (3)

A

Lipid soluble molecules
Microorganisms are not permitted
Drug entry is limited

32
Q

Exception to the rules of entry (2)

A

Circumventricular organs
3rd and 4th ventricle

33
Q

What abnormalities can occur in the brain? (3)

A

Stenosis
Aneurysm
Arteriovenous malformation

34
Q

What is a stenosis? (1)

A

Narrowing of inside of a blood vessel

35
Q

What is an aneurysm? (1)

A

Dilatation of artery wall

36
Q

What is Arteriovenous malformation? (3)

A

Progressive reduction in size of vessels carrying blood the brain
Shunting of smallest vessel/arteries
Circulation drawn away from brain tissue and blood drawn from veins to arteries

37
Q
A