The main psychoactive component of marijuana is tetrahydrocannabinol (THC). What are the effects of this chemical on the human body and mind? Understanding the science behind THC’s impacts helps cannabis consumers use more mindfully and safely. THC elicits most of its effects in the body and brain by binding with cannabinoid receptors.
These receptors make up part of the larger endocannabinoid system (ECS), which is involved in regulating various physiological processes related to appetite, pain sensation, mood, and more. The ECS produces its endogenous cannabinoid molecules called endocannabinoids. THC has a similar molecular structure, which allows it to stimulate cannabinoid receptors just like natural endocannabinoids would. Since THC is much stronger and more long-lasting, it throws the entire ECS out of balance, leading to the widely-recognized cannabis “high”.
How THC enters the brain?
When cannabis is smoked, THC quickly diffuses into the bloodstream through lung tissue and starts circulating throughout the body. It crosses the blood-brain barrier a membrane that filters substances going to and from the brain and accesses the central nervous system within seconds to minutes of inhalation. Oral ingestion leads to slower absorption over 30 minutes to 2 hours as the compound travels through the digestive system first. No matter how it gets into the system, THC eventually reaches the brain, where it triggers systemic changes by activating cannabinoid receptors in various brain regions.
Effects on brain regions and processes
When THC is administered in moderate or high doses, cannabinoid receptors in multiple brain regions are overstimulated, causing different effects.
- Prefrontal cortex – Impaired attention, decision-making, planning
- Hippocampus – Altered memory formation and perception of time
- Cerebellum – Reduced motor coordination and balance
- Basal ganglia – Pleasure, appetite stimulation
what is thc? THC also stimulates the brain’s dopamine system leading to euphoric and rewarding sensations. At the same time, it changes neurotransmitter release and neuronal firing patterns throughout the brain suppressing normal communication pathways. These combined impacts alter sensory perception, cognition, movements, emotions, and consciousness and cause other classic cannabis intoxication signs like heightened sociability and creativity, laughing fits, sedation, lethargy, distorted perception of space and time, increased heart rate, and more.
Effects on the body
Along with getting users “stoned”, THC induces many physical effects through widespread activation of the endocannabinoid system.
- Increased appetite – CB1 receptor stimulation triggers hunger signals
- Relaxation of smooth muscles – reduces gut motility, uterine contractions
- Analgesia – interferes with pain transmission pathways
- Improved sleep – modulates sleep-wake cycle through circadian mechanisms
- Enhanced senses – CB1 stimulation heightens sight, smell, taste, touch, and hearing
The brain attempts to adapt to constant THC stimulation by reducing natural cannabinoid receptor activity through a process called downregulation. This dampening of the ECS leads to tolerance, needing more consumption to achieve the same effects. When high concentrations suddenly drop due to stopping intake, it leaves an endocannabinoid deficiency. As more regions explore legalization, implementing harm reduction education and consumer protections will enable society to capture cannabis’ potential benefits while minimizing risks linked with irresponsible THC exposures.
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