Your brain is highly susceptible to damage and disease from material that might be circulating around in the blood. The blood brain barrier (BBB) is designed to guard against these brain damaging substances from reaching it.
How this is achieved is via unique capillaries. Capillaries everywhere else in your body are lined with endothelial tissue cells that have small spaces between them which allows for relative free movement of stuff in and out.
However, the capillaries leading to your brain don’t have these openings. Instead, the endothelial cells are sealed together, creating a tight fit for which brain damaging chemicals and pathogens cannot breach.
Also, these brain capillary cells are surrounded by astrocytes. These cells are involved in the selection of which substances are allowed to pass.
Your BBB has a couple important functions:
- maintenance of brain homeostasis
- protection against “foreign substances” that may cause brain damage
- protection against hormone & neurotransmitter influence that’s vital for the rest of the body
Lipid-soluble substances can pass readily into your brain, such as:
Whereas, some of the material that cannot get by the blood brain barrier or can only enter very slowly are:
- many drugs
- radioactive ions
- most antibiotics
- chemical compounds
- disease causing organisms ~ virus, bacteria
Unfortunately, it’s the BBB’s tight guard preventing many beneficial drugs from reaching their brain damaging targets for treatment.
Various neurological diseases can change the permeability of the BBB. Some of the health and environmental conditions that can affect your blood brain barrier are:
- multiple sclerosis
- hepatic encephalopathy
- infections ~ meningitis, encephalitis
- high concentration of a substance in your blood
Bacterial infections of the brain are often very serious. Although, the blood brain barrier is very effective in guarding against many common bacteria, once infected the antibodies, sent out to battle them, and antibiotics are too large to cross the BBB. Thus, bacteremia needs to treated ASAP.