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CrateDane t1_j8sm4jy wrote

Neurons, especially in the CNS (brain/spinal cord), are quite sensitive, and are usually kept in a sheltered environment separated from the blood by the blood-brain barrier. Astrocytes and other glial cells provide a controlled environment for the neurons. They do take nutrients from the blood, but they act as a filter to only let through the right things and in the concentrations that neurons prefer.

Even in other tissues, blood isn't usually supposed to leave the blood vessels, and can cause trouble if it does. Perhaps the easiest to understand is coagulation - if everything's clotted up, that will disrupt whatever else is supposed to be happening in that tissue. There are also immune molecules which tend to get activated and cause inflammation when outside blood vessels. Inflammation generally interferes with regular tissue function, and CNS neurons are particularly sensitive to it.

Blood also contains higher concentrations of stuff like iron that would damage neurons.

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jimb2 t1_j8ufwkf wrote

Also, pooled non-circulation blood is an infection risk. "Bacteria love blood."

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edjumication t1_j8utkn6 wrote

I know this isn't a perfect analogy, but I'm imagining like how fuel and air power the combustion in an engine, but you wouldn't want it in the oil system.

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deepeddit t1_j8vfj51 wrote

Can blood/brain barrier be breached by bacterial infection thus damaging the brain? I am asking this because someone close to me was recently treated for sepsis and infection on spine, left the hospital but is now investigated for dementia due to saviour symptoms that started during the infection? Just wondering 🤔

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utterlyuncool t1_j8vovv1 wrote

Yes it can. During any infection of the CNS the blood brain barrier becomes more porous for everything, and people experience CNS symptoms. If the infection destroyed some neurons, those don't grow back. CNS neuronal damage is permanent.

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LibertarianAtheist_ t1_j8x1kic wrote

>If the infection destroyed some neurons, those don't grow back. CNS neuronal damage is permanent.

I still wonder why I had (and have) worse motor distance latency than sensor distance latency at the test my neurologist did before EMG, which is called "Nerve Conduction Study". Abnormal values. The EMG results were ok.

He asked me if I was exposed to toxins as a I child.

Initially I thought: maybe rapid development during puberty contributed to the stretching of nerves affecting those just like stretch marks? But then why would it only affect motor speed and not sensor?

Probably it has something to do with what you wrote. Irreversible damage/death of neurons due to childhood illnesses or something. Why motor and not sensor is an open question, could be different parts of the CNS affected.

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Bax_Cadarn t1_j8udy5w wrote

I would like a neurologist/immunologist to correct me if I'm wrong but. Isn't the biggest reason is that while differenciating leukocytes reacting with brain's molecules aren't destroyed the same way ones reacting with other irgans are? So basically they see a foreign material and attack it?

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WormRabbit t1_j8vu6qa wrote

What is the blood-brain barrier physically made of? If I opened a head, what would it look like?

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CrateDane t1_j8w281q wrote

There are thin cells called pericytes wrapped around the small blood vessels, and around that you have extensions of astrocyte cells. The barrier is too small to see with the naked eye.

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