How does nicotine lead to decreased oxygenation and increased heart rate?

Nicotine leads to decreased oxygenation and increased heart rate primarily through its effect on the cardiovascular system. When nicotine is introduced into the body, it activates the sympathetic nervous system, resulting in vasoconstriction. This narrowing of blood vessels reduces blood flow, which can lead to decreased delivery of oxygen to tissues. In response to this diminished oxygen supply, the heart compensates by increasing its rate to circulate blood more effectively, attempting to meet the body's oxygen demands despite the impaired circulation.

The interplay between reduced blood flow due to vasoconstriction and the increased heart rate resulting from the body's compensatory mechanisms is central to understanding how nicotine negatively impacts oxygenation. This response indicates a greater workload on the heart, leading to potential strain and further complications, such as cardiovascular disease over time.