its about blood brain barrier

1. Blood brain barrier

2. BBB
• The blood-brain barrier (BBB) is a
membrane that controls the passage of
substances from the blood into the central
nervous system.
• It is a physical barrier between the local
blood vessels and most parts of the
central nervous system itself, and stops
many substances from travelling across it.
• The BBB is permeable to alcohol, and
some heavy metals can cross the blood-
brain barrier as well.

3. BBB

4. BBB

5. BBB

6. BBB
• Physiology
• In the brain, endothelial cells are packed much
tighter together, due to the existence of zonula
occludens (tight junctions) between them,
blocking the passage of most molecules.
• The blood-brain barrier blocks all molecules
except those that cross cell membranes by means
of lipid solubility (such as oxygen, carbon dioxide,
ethanol, and steroid hormones) and those that are
allowed in by specific transport systems (such as
sugars and some amino acids).
• Substances with a molecular weight higher than
500 daltons generally cannot cross

7. BBB Physiology
• Many drugs are unable to pass the barrier, since
98 percent of them are heavier than 500 daltons.
• hormones generally do not penetrate the brain
from the blood, except at the 'circumventricular
organs
• The blood-brain barrier is an effective way to
protect the brain from common infections.
• as antibodies are too large to cross the blood-
brain barrier, infections of the brain when they
do occur can be very serious and difficult to
treat.

8. BBB break
• The BBB can be broken down by:
• Hypertension (high blood pressure): high blood
pressure opens the BBB
• Development: the BBB is not fully formed at birth.
• Hyperosmolitity: a high concentration of a substance
in the blood can open the BBB.
• Microwaves: exposure to microwaves can open the
BBB.
• Radiation: exposure to radiation can open the BBB.
• Infection: exposure to infectious agents can open
the BBB.
• Trauma, Ischemia, Inflammation, Pressure: injury to
the brain can open the BBB.

9. Drug Delivery and the Blood-Brain Barrier
The BBB is permeable to small and lipophilic
(fat-loving) molecules (up to 800 atomic mass
units), but larger molecules are not transported
across unless there is an active transport system
available
• Thus this is one of the stumbling blocks for drug
delivery
• An additional problem is the very effective drug
efflux systems (P-gly-coprotein – P-gp ), which
pump the drug back out of cells.

10. drug delivery across BBB