The respiratory and circulatory systems bring oxygen and nutrients to the cells. The respiratory and circulatory systems work together to maintain homeostasis. The respiratory system moves gases into and out of the blood.
Sand dunes or desert pavement
Mass is what you would measure in kilograms
Nicotine, once in the brain, will work specifically on nicotinic receptors in the brain. However, there is a common "addiction" pathway in the brain that pretty much all addictive substances go through.
