Protection & Support of the Brain: Blood-Brain Barrier (BBB)

where is the BBB NOT present

- choroid plexus - hypothalamus - pineal gland

capillaries forming the BBB exhibit 3 structural differences from other capillaries

1. endothelial cells contain tight junctions (prevent the passage of materials between cells), so most substances must move through the endothelial cells & their movement is controlled by membrane transport processes 2. capillary wall is made more substantial by a thickened basement membrane that restricts the passage of substances from the blood into the brain 3. capillaries forming the BBB are wrapped in the perivascular feet of astrocytes, which form the outermost portion of the BBB

what is the function of the blood-brain barrier?

help prevent transport of harmful substances from the blood into the brain that could negatively affect brain function

lipid-soluble molecules cross plasma membranes by simple diffusion, so lipid-soluble molecules such as ____________, ____________, & some anesthetics can diffuse across the _________________ plasma membranes, past the blood-brain barrier & into the ______________ ___________ of the CNS to reach the brain neurons

nicotine, alcohol endothelial interstitial fluid

composition of the blood-brain barrier

specialized capillaries surrounded by astrocytes - capillaries typically composed of endothelial lining resting on a basement

Blood-Brain Barrier (BBB)

structure formed by capillary endothelial cells & astrocytes that regulates what can enter the interstitial fluid in the brain

true or false: The BBB acts as a gatekeeper to control which materials pass from the blood into the brain

true

true or false: drugs such as cocaine & methamphetamine can damage the BBB

true