1. The drawing of the Homunculus refers to the visual representation of the brain map which marches the parts of the body to the area of the brain that control them. Scientists map the brain by stimulating the sensory or the motor cortex with a weak electric current. The stimulation usually produce corresponding movement or tingling sensation in the affected part of the body. The area of the brain which are devoted to each body part is represented in the homocunlus based on the largeness of the structure.
2.On the homunculus, some areas such as the lips, hands and feet are drawn larger than other areas such as arms and the legs. This is because, part of the body such as the lips, hands and feet are specialized structures which are used for making small, precisely controlled movements while the other parts such as the arms and the legs usually make large and less precise movements.
I would explain the bad things smoking does to you and your body. Since he's still a bit young I'd be easy with him. I would probably tell a trusted adult as well.
