Where drugs act: the brain's regions
Gives you the geography: which region controls breathing, movement, reward and mood — so a drug's effects map to places.
Where this fitsConnects to 2 · Unlocks 2
- Connects to
- Dopamine: receptor families, clearance and pathways — Dopamine pathways run between these regions (VTA → nucleus accumbens, substantia nigra → striatum).
- Primary effects and side effects — Side effects often come from the same target in a different region.
- Unlocks
- The neuron and the action potential — Zoom from regions into the cells that make them up.
- Dopamine: receptor families, clearance and pathways — You'll need the VTA, nucleus accumbens and substantia nigra for dopamine pathways.
Walk through
Hindbrain — life support
The brain stem controls breathing, heart rate, blood pressure, digestion and sleep–wake cycles. Inhibiting breathing is the major fatal overdose risk (opioids — but not cannabis). The cerebellum coordinates balance and movement; inhibiting it causes ataxia, as with alcohol.
Analogy and worked example
Analogy: The brain is like a city. The hindbrain is the power plant and water works (stop them and everything fails). The midbrain's VTA is a dispatch office sending 'this is worth it' messages to the limbic neighborhood. The basal ganglia are the traffic system for movement. The cortex is city hall, planning ahead.
Why can an opioid overdose kill, while a large dose of cannabis usually doesn't?
- Ask which region controls the life-critical function at risk: breathing → brain stem (hindbrain).
Tip: the ← and → keys move through the lesson.
Full lesson: CNS/PNS and brain regions