I Brake for Blood-Brain Barriers
Your brain is an elitist. Don’t make excuses. It’s just the way it is—and it’s a good thing.
Here’s what I mean—your brain, like the rest of your body, needs oxygen. And like the rest of your body, your brain gets oxygen from your blood. But here’s the rub—there’s a lot of junk floating around in your blood. Take a sample of your blood and you’ll find all sorts of things—hormones, ions (charged particles), metals and the like all hanging out and taking a dip in the blood stream. For the rest of your body, this junk either serves a purpose or is usually fairly benign. The functioning of your nervous system, however, is reliant on the chemical super-sensitivity of your neural cells, so we can’t have just any chemicals entering your nervous system willy-nilly or things would go to pieces. Hence the blood-brain barrier. Here’s how it works:
Throughout most of your body, capillary walls are full of small openings that allow particles to diffuse in and out of the blood stream. In the nervous system, these holes are sealed up, and the cells of the capillary walls are connected through what are called “tight junctions” (see diagram). Tight junctions keep particles from freely traveling from inside the capillary to outside the capillary and vice-a-versa. The only way particles can move across the capillary wall is if they go directly through the cells that make up the capillary walls cells, and those cells are picky about what they let through. When the blood-brain barrier is tight and working, your brain function is protected from all the rubbish in your blood. When the blood-brain barrier breaks down, neural function suffers. In fact, the breaking down of the blood-brain barrier is associated with a number of neuropathological conditions such as multiple sclerosis, AIDS, childhood lead poisoning and perhaps even Alzheimer’s.
- You’ll have to use your imagination with this diagram–the blue cells are the cells of a capillary wall. Tight junctions form a seal between the cells of the capillary wall and keep all the riffraff in the blood out of the nearby nervous system.
So if your blood-brain barrier is working today, give it three cheers. It’s a silent but vital friend. Brake for blood-brain barriers—after all, most things all ready do.
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