What do you think about BBB?
BBB is a strong wall between the blood and brain fluid which give protection for brain from inside injuries. -Why? Because the blood may be filled with wastes and some foreign bodies so this barrier will not allow anything to enter the brain. ----- We can found BBB in all capillaries inside the brain (except in some regions) -why? Because in those regions some substances are secreted in the blood that should pass easily to the brain. For example: hypothalamus and the hormones that secret it. ----- * IMPORTANT * We should know that capillaries in our bodies differ than in the brain. -How? Normal blood vessel wall made of endothelial cell and between these cells there is pores that permit substances to diffuse out of capillaries, but in brain blood vessels these pores is closed tightly by tight junction and surrounded bu glial cells which make BBB. ----- Transport properties: -Highly permeable to water, CO2, O2 and most lipid soluble substances. -slightly permeable to electrolytes such as sodium, chloride and potassium. - totally impermeable to plasma proteins and most non lipid soluble large organic molecules -glucose transport isotype-1 (Glut1) -Amino acid carrier systems -Metabolic BBB enzyme systems
