Building blocks
Isoprene
Terpenes are repeating C5H8 units stacked into 10, 15, 20, 30, or 40 carbon frames
Shape
Those stacks can be simple chains or folded rings
THC path
Key enzymatic steps toward THC run through terpene pathways
Bonds
Terpenes can attach to other molecules and change how tissues respond to them
How they meet THC
Own signal
Some terpenes may occupy brain receptor sites and change output on their own
Weak CB1
A few, such as thujone from wormwood, bind CB1 only weakly
Gates
Others change membrane or blood-brain barrier leakiness, letting more or less THC through
Mood chemistry
Some shift serotonin or dopamine handling. Mixed oils can add or cancel each other
How many, and where
Count
More than 100 terpenes have been named in cannabis, plus many close variants
Smoke share
About 10 to 30 percent of smoke resin can be terpenes
Same glands
They are made in trichomes, the same glands that make THC
Cousins
Hops and black pepper carry overlapping terpene sets. Hemp and high-THC cannabis do too
What changes the profile
Evaporation
Many terpenes leave the plant at temperatures as low as 75 F (24 C)
Morning test
The same plant often smells stronger at the end of the dark period than after a bright day
Ripening
Odor usually gets louder and sometimes shifts as buds finish
Soil and feed
The same variety can make different oil amounts, and maybe different oils, in different media