Cerebral Circulation

Question 1

What is the total cerebral blood flow?

Answer 1

750 mL/min

Question 2

Approximately what percent of body weight is the brain?

Answer 2

2%

Question 3

What percent of resting CO will the brain get?

Answer 3

13-14%

Question 4

How long does it take for lack of cerebral blood flow to induce fainting?

Answer 4

5 seconds

Question 5

Cerebral blood flow under what value (mL/min) will cause irreversible brain damage?

Answer 5

10 mL/min

Question 6

At what CBF value does cerebral impairment begin? Flat line EEG?

Answer 6

20-25 mL/min; 15-20 mL/min

Question 7

What is the flow to the grey matter in mL/min/100g? White matter?

Answer 7

60-80; 20

Question 8

The brain consumes what percentage of resting oxygen?

Answer 8

20%

Question 9

What is the%O2 extraction in the brain?

Answer 9

30% extraction

Question 10

What percent of body’s glucose is used by the brain at rest?

Answer 10

50%

Question 11

How does the brain autoregulate cerebral blood flow?

Answer 11

Changes in resistance (vasodilation/ vasoconstriction)

Question 12

What is the effect of arterial PCO2 on cerebral blood flow?

Answer 12

Small increases in PCO2 result in large increases in CBF

Question 13

What is the effect of increasing ventilation on cerebral arteriole radius?

Answer 13

Vasocontriction

Question 14

Neurometabolism is especially effective at regulating what kind of blood flow?

Answer 14

Regional blood flow

Question 15

What metabolites stimulate vasoconstriction?

Answer 15

H+, K+, adenosine, CO2,

Question 16

What is flow-metabolism coupling?

Answer 16

Increased blood flow to active tissue

Question 17

What types of cells are included in the neurovascular unit?

Answer 17

Endothelial, pericytes, astrocytes

Question 18

What is the ratio of pericytes to endothelial cells?

Answer 18

1:03

Question 19

How does glutamate mediate vasodilation?

Answer 19

Glutamate binds to NMDA receptors on neurons, allowing for calcium influx which activates nitric oxide synthase, producing NO and causing vasodilation

Question 20

True or False: SNS stimulation is not necessary to maintain proper cerebral blood flow?

Answer 20

FALSE

Question 21

What is the strongest extrinsic activator of the cardiovascular system?

Answer 21

Cerebral ischemia

Question 22

What is Cushing’s Reflex?

Answer 22

A physiological nervous system response to an increase in intra-cranial pressure

Question 23

What is Cushing’s Triad?

Answer 23

Hypertension, Brandycardia, slow-irregular breathing

Question 24

What structures create the brain-blood barrier?

Answer 24

Cerebral endothelial cells in the capillaries have continuous tight junctions with end/foot of an astrocyte surrounding the capillary

Question 25

What is the clinical use of mannitol? What is the basis of its action?

Answer 25

Can be used as an oncotic agent to draw water out of the brain; carbohydrate that cannot cross BBB- oncotic agent

Question 26

True or False: The blood brain barrier is has an equal permeability throughout the brain?

Answer 26

FALSE

Question 27

What compounds can the brain use for energy?

Answer 27

Glucose and ketone bodies

Question 28

What is the most important glucose carrier in the brain?

Answer 28

GLUT1

Question 29

What is the aproximate volume of CSF?

Answer 29

100-160 mL

Question 30

What produces cerebrospinal fluid?

Answer 30

Choroid plexus

Question 31

How much CSF is made daily?

Answer 31

400-600 mL

Question 32

What are the functions of CSF?

Answer 32

Buoyancy, Shock absorption, intracerebral transport

Question 33

Where does the CSF circulate throughout the brain?

Answer 33

Subarachnoid space

Question 34

Where is CSF reabsorbed into the venous system?

Answer 34

Arachnoid villi (granulations) into the superior sagittal sinus

Question 35

What is the relationship between cerebrospinal fluid and extracellular fluid?

Answer 35

They are in communication/equilibrium with one another