Ganja. It has effects on the nervous system and the immunity systems. Its the nervous systems effects that are most problematic as there is no separation between the beneficial (like nausea, appetite etc.) effects and the harmful (craving, addiction, misuse, high, reward center stimulation) effects. Better not to start using this.
Ganja. Nervous system.
Brain & Lungs. Using cannabis causes distorted perceptions, impaired coordination, difficulty with thinking and problem solving, and problems with learning and memory. Used chronically, marijuana's adverse effects can impact learning & memory for days or weeks after the drug wears off. +addiction potential. Also, lung irritation -- marijuana smoke contains more carcinogenic compounds than plain cigarettes.