Blood Brain barrier Flashcards
Where is the BBB located?
In the blood capillary
What are the cellular components of the BBB?
- Endothelial cell
- Pericyte
- Astrocyte
What does the preicyte do?
-They are contractile cells that wrap around the endothelial cells that line the capillaries and venules
The pericyte and astrocytes wrap around the barrier making it tight. TRUE OR FALSE?
TRUE
The capillaries form 95% of the BBB. TRUE OR FALSE?
TRUE
What does the endothelial cell line?
They line the capillaries
What are endothelial cells surrounded by?
- Collagen
- Fibronectin
- Laminin
What does the astrocyte foot processes secrete?
-Paracrines that promote tight junction formation
Tight junctions do not prevent solute movement between endothelial cells. TRUE OR FALSE?
FALSE
What two types of proetins are found in a tight junction?
- Intergral membrane proteins
- Cytoplasmic accessory proteins
LIst the differences between Intergral membrane proteins and Cytoplasmic accessory proteins
Intergral membrane proteins:
- Claudin
- Occludin
- Junctional adhesion molecule
Cytoplasmic accessory proteins
- Zonula occludens
- Cingulin
What is the function of arachnoid cells?
Helps keep the content of the central nervous system stabilized (i.e prevent movement)
How much CSF is in the brain?
100-160ml
How much CSF does the brain produce per day?
500ml
What is the rate of CSF replacement?
about 4 times
What the functions for CSF?
- Provide mechanical protection
- Maintain a stable extracellular environment for the brain
- Removes some waste products
- Nutrition
- Convey messages / hormone releasing factors/NT
What are the different types of transport mechanism that occur in the BBB?
- Passive diffusion
- ABC transporter efflux
- Solute carriers SLC
- Transcytosis receptor mediated adsorptive mediated
- Mononuclear cell migration
What type of molecules are transported across the different types of transport mechanism?
-Passive diffusion (lipid soluble/non polar molecules) -ABC transporter efflux (lipid soluble/non polar molecules and conjugates) -Solute carriers SLC (Glucose/AAs/Nucleosides) -Transcytosis receptor mediated adsorptive mediated (Transferrin/lipoproteins/insulin/IgG) - Mononuclear cell migration (Cationised albumin/histone)
Drugs/Molecules that are more lipohilic will have greater permeability tthan drugs that are more hydrophilic. TRUE OR FALSE?
TRUE
Which of these, glucose, lactate, essential AAs or organic anion transporter cannot cross into the blood but can cross into the brain?
organic anion transporter
What is transcytosis?
Endocytosis + Exocytosis
Give examples of receptor mediated transcytosis?
Transferrin
Insulin
Erythropoietin
Give an example of an adsorptive mediated transcytosis?
Albumin
What type of molecules are not permitted to enter into the brain?
- Large molecules
- Low lipid soluble molecules
- High electrical charge
What are the functions of the BBB?
- Protects the brain from foreign substances in the blood that may cause injury to the brain
- Protects the brain from hormones and NT in the rest of the body
- Transports nutrients into the brain
- Move out toxins of the brain
- Maintains a constant environment for the brain
- Essential for brain normal functions
The BBB is permeable to small and lipophilic molecules. TRUE OR FALSE/
TRUE
Larger molecules are not transported across unless there is an active transport system available. TRUE OR FALSE/
TRUE
What occurs in efflux drug systems and give an example?
Drugs are pumped back out of cells
e.g P-gly-coprotein-p-gp
A large proportion of drugs can cross the BBB. TRUE OR FALSE?
FALSE
What are the strategies of delivering drugs to the brain?
Go through: -the use of endogenous system -disturbing the BBB -Produgs Go behind: -Intraventricular/intrathecal route -olfactory pathway -interstitial delivery
