blood brain barrier water oxygen alcohol passage

The blood–brain barrier is selective, not sealed

The blood–brain barrier blocks many substances from moving easily from the blood into the brain, but it is not completely sealed. Water, oxygen and carbon dioxide can cross it, as can many fat-soluble substances, including alcohol and some anesthetics.

A tiny excess of matter was enough to build the universe we see

≈1 in 100 million

The early universe contained almost equal amounts of matter and antimatter. When the two destroyed each other, only a tiny excess of matter remained—about one surviving particle for every 100 million original matter particles. That small leftover became the matter around us today.

Animals depend on microbes for vitamin B12

Vitamin B12 is produced naturally by certain bacteria and archaea, not by animals or plants. Animals obtain it through their diets or relationships with microorganisms. Humans get B12 mainly from animal-derived foods, fortified products or supplements. A vitamin essential to human health ultimately originates in microbial metabolism.

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blood brain barrier water oxygen alcohol passage

The blood–brain barrier is selective, not sealed

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