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Block 5 (Basic Neuroscience) > (Lecture 7) Cerebral Blood Flow and Cerebral Metabolism > Flashcards

(Lecture 7) Cerebral Blood Flow and Cerebral Metabolism Flashcards

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1
Q

What occurs after 10 seconds of brain ischemia?

A

Loss of consciousness

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2
Q

A condition wherein there is not enough blood flow to the brain.

A

Brain ischemia

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3
Q

How long does brain ischemia have to prevail before brain electrical activity ceases?

A

20 seconds

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4
Q

True or false: irreversible brain damage usually begins after 30 secs.

A

False. After a few minutes

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5
Q

The brain is very dependent on what type of metabolic process?

A

Oxidative glycolysis

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6
Q

How are blood vessels arranged in the CNS?

A

In a meshwork (particularly in gray matter). From the surface going inside.

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7
Q

What are the vessels that supply the cerebral blood flow.

A
  1. &2. Two carotid arteries

3. &4. Two vertebral arteries.

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8
Q

Large vessels that merge to form the circle of Willis

A

L,R vertebral arteries and L,R internal carotid arteries (4 in total)

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9
Q

Arteries arising from the Circle of Willis travel along the surface of the brain and give rise to what arteries?

A

Pial arteries

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10
Q

Pial arteries branch out into smaller vessels called:

A

Penetrating arteries and arterioles

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11
Q

The penetrating vessels are separated SLIGHTLY from the brain tissue by:

A

Virchow-Robin space

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12
Q

Virchow-Robin space is an extension of:

A

Subarachnoid space

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13
Q

It is where the exchange of nutrients, oxygen, CO2, and metabolites occur.

A

Capillaries

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14
Q

Capillaries branch out from these structures. Also, these are penetrating vessels that dove down into the brain tissue.

A

Intracerebral arterioles

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15
Q

Enumerate the sequence of vessels that supply blood into the brain.

A
  1. (Four large arteries (2 internal carotid arteries and 2 vertebral arteries)
  2. Circle of Willis
  3. Arteries travelling around the brain surface
  4. Pial arteries
  5. Penetrating arteries
  6. Penetrating arterioles
  7. Intracerebral arterioles
  8. Capillaries
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16
Q

Normal blood flow through the brain.

A

50-65 ml /100 grams brain tissue/min

OR

750-900 ml/min for the entire brain

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17
Q

The brain constitutes about how much of body weight?

A

2%

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18
Q

The brain receives how much of the resting cardiac output?

A

15%

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19
Q

Metabolic factors that are believed to contribute to cerebral blood flow regulation.

A
  1. CO2 concentration
  2. O2 concentration
  3. H+ concentration
  4. Substances released from astrocytes
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20
Q

These are specialized non-neuronal cells that appear to couple beuronal activity with local blood flow regulation

A

Astrocytes

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21
Q

A localized dilatation in the internal carotid artery near the bifurcation of the common carotid artery.

A

Carotid sinus

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22
Q

The internal carotid artery divides into two vessels which form the anterior circulation that supplies the forebrain.

A

Anterior and middle cerebral arteries

23
Q

Connects the two anterior cerebral artery.

A

Anteriir communicating artery

24
Q

Position of the anterior cerebral artery in reference to the optic nerve.

A

Medially superior

25
Q

Largest branch of the internal carotid artery.

A

Middle cerebral artery.

26
Q

Runs laterally in the lateral cerebral sulcus.

A

Medial

cerebral artery

27
Q

Supplies all the motor area of the brain except the leg area.

A

Middle cerebral artery

28
Q

Arteries that branch out from the middle cerebral arteries.

A

Lenticulostriate arteries

29
Q

Lenticulostriate arteries supoly which parts of the brain?

A
  1. Basal ganglia

2. Thalamus

30
Q

Increased H+ conc. leads to:

A

Depression of neuronal activity. (Greatly)

31
Q

Physiologic compensation in response to the increased H+ conc. in cerebral blood flow.

A

Increased cerebral blood flow.

32
Q

Other substances aside from CO2 which increase brain tissue acidity.

A

Pyruvic acid, lactic acid, and other tissue metabolic products.

33
Q

Normal rate of oxygen utilization by the brain tissue.

A

3.5 (+/- 0.2) ml O2 per 100 grams of brain tissue per minute

34
Q

Oxygen deficiency triggers:

A

Vasodilation (thus returning cerebral blood flow back to normal)

35
Q

Normal value of cerebral tissue partial pressure of O2.

A

35 - 40 mmHg

36
Q

Cerebral tissue partial pressure at which cerebral blood flow begins to increase.

A

Below 30 mmHg

37
Q

PO2 value at which brain function becomes deranged.

A

Below 20 mmHg (even coma can occur)

38
Q

Gray matter astrocytes are also known as:

A

Protoplasmic astrocytes

39
Q

T/F: Cerebral blood flow autoregulation protects the brain from fluctuations in arterial pressure changes.

A

True

40
Q

Constant rate of cerebral blood flow is regulated in this range of mean arterial pressure.

A

60-140 mmHg

41
Q

What happens when mean arterial pressure falls below 60mmHg?

A

Cerebral blood flow becomes severely decreased

42
Q

T/F: Cerebral blood flow autoregulation mechanism can override the nervous effects.

A

True. (Mild to moderate stimulation of the sympathetic nerves that innervate the cerebral circulatory system causes little change in cerebral blood flow)

43
Q

How is cerebral stroke prevented during engagement in strenous activities?

A

Sympathetic nervous system stimulates large and intermediate sized arteries to constrict thereby preventing high pressure from reaching the smaller blood vessels.

44
Q

The overall metabolic rate of the brain is gray matter is how many times greater than that of white matter?

A

4x

45
Q

Support the brain capillaries and prevent relatively excessive leakage of fluid.

A

Glial feet (Also provide physical support to prevent over stretching of capillaries in case of high capillary pressure)

46
Q

T/F. Hypertensive people have a much thinner small arteriole walls.

A

False (Thicker)

47
Q

These thickened arteriolar walls are constricted most of the time. Why?

A

To prevent transmission of high pressure to capillaries.

48
Q

The major need for metabolism in neurons is due to:

A

The need to pump Na and Ca ions to the outside of the neuronal membranes and K ions to the interior.

49
Q

During high levels of brain activity, neuronal metabolism can increase as much as:

A

100 to 150 %

50
Q

T/F. The brain is capable of much anaerobic metabolism.

A

FALSE. The brain is highly metabolic and need a second-by-second delivery of oxygen from blood.

51
Q

MAJOR, MAJOR source of energy used by brain cells.

A

Glucose

52
Q

Trivia:

A

Glucose must also be delivered sec-by-sec from the capillary blood

53
Q

T/F: Transport of glucose into the neurons through the cell membrane is not dependent on insulin.

A

True

54
Q

Why can over treatment of insulin lead to psychosis and mental imbalance?

A

Because blood glucose level falls extremely due to transport of all the glucose into insulin-sensitive tissues (non-neural cells) leaving no more glucose for neurons

Block 5 (Basic Neuroscience) (3 decks)

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