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.
When food is digested, it is absorbed into the blood from the small intestine walls. From there the blood is drained into the hepatic portal vein. The hepatic portal vein then â¦ goes to the liver. The blood in this vein is very rich in nutrients.he energy is used by the entire body. The heart also uses it to pump blood around the body. This is the connection between the digestive and circulatory system. The small intestine contains many blood vessels which absorb the nutrients from the food into the blood.