BBB

• Paul Ehrich, in the 19th Century, injected dye into the mouse bloodstream, and the dye infiltrated all tissues except the brain and spinal cord.
• The Blood Brain Barrier (BBB) is a protective barrier that separates the brain from the bloodstream.
• The BBB is composed of three layers: the endothelium, the basement membrane, and the pia mater.
• The endothelium is the inner layer of the BBB, and it is responsible for controlling the transport of substances into and out of the brain.
• The basement membrane is the middle layer of the BBB, and it is responsible for maintaining the structure of the BBB.
• The pia mater is the outer layer of the BBB, and it is responsible for protecting the brain from damage.
• The BBB allows small uncharged molecules like oxygen and carbon dioxide to pass through freely, but it blocks fat-soluble molecules like vitamins A and D, drugs affecting the brain, and illegal drugs.
• Fat-soluble molecules dissolve in the fats of the membrane, and the BBB uses special protein channels to allow the passage of glucose, amino acids, purines, choline, some vitamins, and iron.
• Active transport is a protein-mediated process that expends energy to pump chemicals from the blood to the brain.
• The BBB is compromised when there is no blood flow in the brain.