Commonly called breathing which is air moved into and out of the lungs. During inspiration and expiration so the gases there are continually changed and refreshed. External respiration. Oxygen diffuses from the lungs to the blood and carbon dioxide diffuses from the blood to the lungs. exchange between external environment (alveoli) & blood*. Transport of respiratory gases. oxygen is transported from the lungs to the tissue cells to the lungs. **THE cardiovascular system accomplishes this transport using blood as the transporting fluid. Internal respiration. oxygen diffuses from the blood to tissue cells, and carbon dioxide diffuses from tissue cells to blood.
While strong stimulants (such as cocaine) can cause seizures, the milder stimulant effects of nicotine and caffeine don't seem to impact on seizure frequency (except with extreme excess use).
The first effects of nicotine withdrawal will be felt within 6 hours of having your last cigarette. However the peak time for these nicotine withdrawal side effects will be the second and third day post-smoking cessation. From then on depending on the factors I mentioned earlier on, nicotine withdrawal will begin to diminish over a 2 â 3 week period. So in effect, you could say on average that nicotine withdrawal will last about 3 weeks. However, it could be shorter in some people and in heavy smokers who have smoked for 20 years or longer, the nicotine withdrawal could last for up to 2 months. So you now have a rough idea of how long nicotine withdrawal does last. Most people will fall in between those withdrawal timelines.