Dopamine is a chemical released by neurons to send signals to other nerve cells. the brain includes several distinct dopamine pathways, one of which plays a major role in reward motivated behavior.
smoking is a habit, in a habit there is the cue, routine, and reward. with smoking the cue can be different things, most commonly stress or anxiety. the routine how you react to those cues, the reward is the chemical 'triggers' that are pulled inside you're brain leaving you feeling calm, happy, or relieved, etc.
Positron Emission Tomography scan of the brain of cocaine addicts showed that the drug affects how the brain use glucose. Cocaine users' brain cannot use glucose efficiently and there are also reduced metabolic activity in other areas of the brain.
The energy<span> from </span>sunlight is stored<span> in the chemical bonds of </span>molecules<span>. ..... </span>during<span> day, CO2 slowly used to make glucose while stomata are closed ... purpose is to produce ATP(</span>energy stored<span> in chemical </span>bonds of sugar<span>) and breakdown.</span>