Quick Answer. The effects of caffeine start within 10 minutes after it is consumed, according to ScienceDaily. However, caffeine requires 45 minutes to reach its maximum concentration in the blood. Continue Reading.
The heart, blood, and blood vessels are the three structural elements that ... These nutrients enter the bloodstream by passing through the walls of the intestine.he heart, blood, and blood vessels are the three structural elements that ... These nutrients enter the bloodstream by passing through the walls of the intestine.
Report Abuse. Almost all the body's nutrients are absorbed into the bloodstream through the small intestine, which has three sub-divisions: the Duodenum, the Jejunum and the Ileum. (Most absorption occurs in the Jejunum, or middle section).