Lp 11

Question 1

-brain is highly metabolic
-blood supply to brain accounts for ~20% of total BVol
*brain tissue accounts for ~20% of body weight
-20% of O2 taken in by the lungs goes to brain

Answer 1

Arterial supply

Question 2

O2 is vital:
-15 sec without o2=
6-9 minutes without o2=

Answer 2

-LOC
-severe irreversible tissue damage

Question 3

Arteries delivering oxygenated blood to brain:

Answer 3

-R & L vertebral arteries
R & L internal carotid arteries
-circle of Willis

Question 4

-emerge from subclavian as
-enter brain via foremen magnum
-supply brain stem, cerebellum, occipital lobe & parts of thalamus

Answer 4

Vertebral arteries

Question 5

-enter through carotid canal
-supply remaining structures; esp. cerebral hemispheres

Answer 5

Internal carotid aa

Question 6

-formed by communicating aa
-anastomoses of anterior & posterior cerebral aa (branches of carotid)

Answer 6

Circle of Willis

Question 7

Factors affecting BF to/within the brain?

Answer 7

-physiological:
*carotid sinus P
*blood (o2) & (co2)
*CSF P

-pathological:
*exception: hemangioma
*arterial obstructive disease
*drugs

Others: anemia; hyperthyroidism & polycythemia; hypothyroidism

Question 8

Venous drainage affected by?

Answer 8

-veins
*dural sinuses
*meningeal vv of dura
*diploic vv (in spongy bone of skull)

Question 9

-circulates in ventricles
-formed by choroid plexuses & ependymal cells

Answer 9

Cerebrospinal fluid (CSF)

Question 10

-blood capillaries enclosed in ependymal lining
-suspended from roofs of ventricles

Answer 10

Choroid plexuses

Question 11

Fxns of CSF

Answer 11

-supportive & protective
-maintains chemical environment
-CSF circulation

Question 12

-protective
-formed by endothelial cells
-highly selective

Answer 12

Blood brain barrier

Question 13

No blood brain barrier in?

Answer 13

-vomiting center
-hypothalamus
-not completely formed in babies
-trauma/ infection increase permeability of BBB