Cannabis is a chemical compound found in the flowers, leaves or extracts of cannabis plant known as marijuana. Smoking marijuana releases psychoactive chemical (tetrahydrocannabinol), which is absorbed into the bloodstream via lungs.
This causes both psychological and physiological effects on the human body.
Effects of cannabis generally range from 10 minutes to 8 hours, depending on the potency of the dose and personal tolerance to the drug's various effects.-(1)
When THC enters the blood stream and reaches the brain, it binds to cannabinoid receptors. Brain regions in which cannabinoid receptors are very abundant are the basal ganglia, associated with movement control; the cerebellum, associated with body movement coordination; the hippocampus, associated with learning, memory, and stress control; the cerebral cortex, associated with higher cognitive functions.-(2)
Acute effects include euphoria, anxiety, Increased heart rate, dry mouth, reddening of the eyes, a reduction in intra-ocular pressure, muscle relaxation and a sensation of cold or hot hands and feet-(3)
Risk for schizophrenia, bipolar disorder and major depression.(4,5)
A study in the academic journal, Cancer Epidemiology, Biomarkers & Prevention, demonstrated that a marijuana cigarette deposits four times the amount of tar in the human respiratory tract than a tobacco cigarette.
Several experiments on animal and human tissue have demonstrated a disruption of short-term memory formation, -(8)
Sources: 1. http://www.erowid.org/plants/cannabis/cannabis_effects.shtml 2. http://www.sciencedirect.com/science/article/pii/S0163725897820013 3. http://web4health.info/en/answers/add-cannabis-physical.htm 4. http://onlinelibrary.wiley.com/doi/10.1111/j.1369-1600.2008.00106.x/abstract;jsessionid=DDBB7D254B3218E650074A1D0E6A1F58.d03t01 5. http://www.sciencedirect.com/science/article/pii/S0303720708000658 6.