system
Given the following post, respond as if you're commenting on Reddit:
human
How do drugs get into the brain?

I have read that LSD binds a specific Serotonin receptor which then fires with Serotonin causing the effects. But aren't receptors things in synapses? How does LSD get there?
gpt
Most drugs have structures that are incredibly similar to natural neurotransmitters! Not to get too into the organic chemistry but serotonin and LSD share the same indole rings. In essence, because of their similar structure, LSD can pretend to be serotonin and affect the same pathways and receptors. To get into the brain, the drugs have to pass the blood brain barrier (BBB). Since the structure is so similar to the natural neurotransmitters that are allowed through that barrier, LSD sort of tricks the membrane into letting it pass.