Blood Brain Barrier (BBB) Flashcards
What is the BBB ?
A highly selective semipermeable membrane barrier that separates the blood from the brain
What is the cellular composition of the BBB ?
Tight Junction
Endothelial cells
Basement membrane
Capillary forms 95% of BBB. TRUE or FALSE
TRUE
What is the function of Tight junction in BBB ?
Prevents solute movement b/wn endothelial cells
Astrocyte foot processes secrete paracrines that form tight junctions. TRUE or FALSE
TRUE
Tight junction of BBB is composed of Integral membrane proteins ad Cytoplasmic accessory proteins. TRUE or FALSE
TRUE
Give examples of Integral membrane proteins
Claudin
Occludin
Junctional adhesion molecule
Give examples of Cytoplasmic accessory proteins
Cingulin Zonula Occludens (ZO)
Identify differences between BBB and Capillaries of Peripheral Organs
- BBB;
contains more tight junctions
has higher tight junction resistance (>1000)
has abundant amount of mitochondria (mitochondria is rare in capillaries of PO)
has no clefts (unlike capillaries of PO)
highly selective transport
Deficient vesicular transport (abundant in Capillaries of PO)
Rare pinocytic vesicles (abundant in capillaries of PO)
Name the blood CSF barrier
Choroid plexus
State functions of CSF
- Provides mechanical protection
- maintains stable extracellular environment for the brain
- removes some waste product
- Nutrition
BBB is not a wall. TRUE or FALSE
TRUE
Name BBB transport mechanisms
- Passive diffusion
- ABC transport efflux
- Solute carriers (SLC)
- Transcytosis (Receptor or Adsorptive mediated)
- Mononuclear cell migration
Water is able pass into the brain. TRUE or FALSE
FALSE. Water can’t enter the brain because it’s charged
Give examples of substances that can pass through the BBB
- Glucose
- Lactate
- Amino acids
Give examples of molecules transported via receptor mediated transcytosis (RMT)
- Insulin
- Erythropoietin (EPO)
- Transferrin
Give examples of molecule(s) transported via adsorptive mediated transcytosis (AMT)
Albumin
Albumin is the most common protein in the blood. TRUE or FALSE
TRUE
Describe properties of molecules that can enter the brain
- Small
- Lipid soluble
- Low charge
State the function(s) of the BBB
- Protects brain from foreign substances of the blood
- Protects brain from hormones and neurotransmitters
- Transports nutrients into the brain
- Moves toxins out of the brain
- Maintains constant environment for the brain
- Essential for normal brain functions
The BBB is permeable to small, lipophilic molecules (up to 400Da). TRUE or FALSE
TRUE
Larger molecules are transported across BBB only via Active transport system. TRUE or FALSE
TRUE
A large proportion of drugs cannot cross the BBB. TRUE or FALSE
TRUE
Drug efflux systems (P-gly-coprotein -P-gp) pump drug back out of cells. TRUE or FALSE
TRUE