Clinical Significance of the Blood Brain Barrier

Question 1

How do capillary endothelial cells in brain and spinal cord differ to those in peripheral tissues?

Answer 1

Brain/spinal cord: tight junctions of high electrical resistance –> provides effective barrier against molecules except water and gases

Periphery: have gaps –> water, ions and molecules up to large protein size can easily diffuse through capillary endothelial cells

Question 2

What is the general name for areas of brain that don’t have a Blood Brain Barrier?

Answer 2

Circumventricular organs

Question 3

What 3 areas make up the circumventricular organs

Answer 3

1. Area postrema:
2. Posterior pituitary gland:
3. Median eminence of hypothalamus:

Question 4

what 2 functions does the area postrema have

Answer 4

a chemoreceptive area that –>

• mediates water balance and homeostatic functions
• senses toxins in blood & triggers nausea/vomiting

Question 5

what is function of the posterior pituitary gland

Answer 5

• allows passage of hormones (eg oxytocin) into circulation

Question 6

what is the fucntion of the median eminence of the hypothalamus

Answer 6

• Connects hypothalamus to pituitary gland
• the lack of a barrier allows secretion of regulatory hormones into bloodstream

Question 7

they are tightly packed

By how many nm are neurons and Astroctyes separated by?

Answer 7

20 nm

Question 8

What % of brain volume is Brain EX. Fluid

Answer 8

20%

Question 9

What are the 4 functions of the blood brain barrier

Answer 9

1. Maintains brain homeostasis & optimal conditions for neuronal function
2. Protects brain from surging fluctuations in plasma ion concentrations
3. Restricts entrance of potentially harmful macromolecules (eg albumin or prothrombin) from environment/diet
4. Allows selective transport of essential nutrients into brain