Nicotine affects the human body in many different ways because it binds permanently and blocks the action of dozens of different types of enzymes.

An excerpt from the article 15 facts about nicotine

In small doses, it has a stimulating effect on the body, causing increased secretion of adrenaline. As a result, you may experience relief from stress, decreased appetite, improved learning ability, arousal, and greater activity. Increased heart rate, dilated pupils, increased heart rate, and increased blood pressure are observed. In some cases, at low dosages, nicotine can stimulate the brain and nervous system, as well as improve concentration and memory. Small doses of nicotine release dopamine in our body, which is called the happiness hormone.