Regional Circulation - Cerebral

Question 1

At what point can arrest of the circulation lead to irreversible damage to the brain?

Answer 1

Unconsciousness = Arrest of circulation for 5s

Irreversible damage = 3 mins

Question 2

The normal cerebral blood flow in an adult is

Answer 2

750 to 900 ml/min for the entire brain.

Question 3

What percentage of cardiac output is cerebral blood flow?

Answer 3

15

Question 4

Average perfusion for CBF

Answer 4

50 to 65 milliliters per 100 grams of brain tissue per minute

Question 5

Hypermia in the brain

Answer 5

Too much blood in the brain can raise intercranial pressure

Question 6

Ischemia in the brain

Answer 6

Inadequate blood supply results in tissue death

Question 7

Blood supply to the brain is normally divided into

Answer 7

Anterior and posterior segments

Question 8

How many arteries supply the brain?

Answer 8

4

Question 9

Which arteries supply the brain?

Answer 9

2 internal carotid arteries on the anterior side

2 vertebral arteries on the posterior

Question 10

What is the circle of Willis?

Answer 10

A circulatory anastomosis that supplies blood to the brain and surrounding structures. It is the origin of six large vessels supplying the cerebral cortex

Question 11

Where is the circle of Willis located?

Answer 11

The base of the brain

Question 12

The circle of Willis is named after

Answer 12

Thomas Willis, an English physician who discovered it and then published his findings in his 1664

Question 13

The vertebral arteries unite to form…

Answer 13

… Basilar artery

Question 14

The main function of the circle of Willis is to…

Answer 14

… provide a collateral blood flow between the anterior and posterior arterial systems of the brain.

Question 15

Structures that make up the circle of Willis

Answer 15

Anterior cerebral artery (L,R)
Anterior communicating artery
Internal carotid artery (L,R)
Posterior communicating artery (L,R)
Posterior cerebral artery (L,R)
Basilar artery

Question 16

Extra importance of the circle of Willis

Answer 16

If one part of the circle becomes blocked or stenosed or one of the arteries supplying the circle is blocked or narrowed, blood flow from all the vessels can preserve cerebral perfusion to avoid symptoms of ischemia

Question 17

There is no crossing of circulation on the left and right sides of the brain. True or false?

Answer 17

True

Question 18

Is the pressure on the left and right sides of the brain equal or not?

Answer 18

It is

Question 19

In normal adult the brain weighs…

Answer 19

1400 gm

Question 20

In children, CBF is…

Answer 20

…double the adult value and it falls to the adult level at puberty.

Question 21

Measurement of CBF is based on

Answer 21

Fick’s principle

Question 22

What are the methods of regulation of CBF?

Answer 22

Intrinsic

Extrinsic

Question 23

Intrinsic regulation of CBF

Answer 23

Cerebral vessels change blood flow through them by altering their diameters in autoregulation.

Question 24

Relationship between cerebral blood vessels and systemic blood pressure

Answer 24

They constrict when blood pressure is raised and dilates when it is lowered

Question 25

Extrinsic mechanisms of CBF regulation

Answer 25

Chemical
Nervous
Mechanical

All external to the brain tissue

Question 26

Brain tissue and CSF are compressible while the blood vessels are incompressible. True or false?

Answer 26

False. It’s the other way around.

Question 27

What is the major source of energy in the brain?

Answer 27

Glucose, and sometimes amino acids during starvation.

Question 28

Fainting is usually caused by…

Answer 28

…changes in ABP

Question 29

Stroke occurs when…

Answer 29

…the blood supply to a part of the brain is blocked as a result of high BP causing the vessels to constrict, resulting in the death of an area within the brain.

Question 30

If smaller vessels constrict during a stroke, the result is…

Answer 30

…disability and loss of some bodily function

Question 31

Types of stroke

Answer 31

Thrombotic
Haemorrhagic
Embolic

Question 32

Thrombotic stroke

Answer 32

Stroke due to the blockage of an artery leading to or in the brain by a bloodclot.

Question 33

Haemorrhagic stroke

Answer 33

Stroke due to bleeding from a ruptured blood vessel, usually a consequence of hypertension.

Question 34

Embolic stroke

Answer 34

Stroke due to the formation of a blood clot in a vessel away from the brain. The clot is carried in the bloodstream until it lodges in an artery leading to or in the brain

Question 35

Dementia results from

Answer 35

repeated episodes of small strokes which produce progressive damage to the brain over a period of time.

Question 36

The main clinical feature of dementia is…

Answer 36

…a gradual loss of memory and intellectual capacity. Loss of motor function in the limbs and incontinence can also occur.

Question 37

The blood brain barrier means…

Answer 37

…a selective permeability of the cerebral capillaries

Question 38

The blood brain barrier is due to…

Answer 38

• Absence of slit pores and tight junctions between capillary endothelial cells
• Lack of vesicular transport mechanism
• End-feet of the astrocytes cells.

Question 39

The blood-brain barrier is highly permeable to…

Answer 39

…water, O2, CO2, and lipid soluble substances as alcohol and anesthetics.

Question 40

The blood-brain barrier is impermeable to…

Answer 40

…plasma proteins, cholesterol or bile pigments.

Question 41

Functions of the blood-brain barrier

Answer 41

i) Protection of the brain from endogenous and exogenous toxins
ii) Maintenance of the local environment of the neurons in the CSF constant
iii) Preventing the escape of local neurotransmitters into the general circulation.