Video Transcript
Consider this picture of key nutrients in fruits and vegetables. After digestion, vitamin C from strawberry and kiwi juice is provided to the body
through blank. (A) Lacteal vessels, (B) the lymphatic system, (C) the hepatic portal vein, or (D)
the superior vena cava.
This question concerns the absorption and transport of a specific vitamin that is
vital to maintaining a healthy diet, vitamin C. Let’s discuss some differences between vitamin A and vitamin C in order to answer our
question correctly. Vitamin C is water-soluble, which means that it can dissolve in water and can
therefore be easily transported in the human body dissolved in blood plasma, which
is 90 percent water. On the other hand, vitamin A is insoluble in water, which changes how it is absorbed
in the digestive tract and transported through the body.
Vitamins, which are found in the food we eat, are mostly absorbed in the small
intestine after this food has been digested, or broken down, into smaller
molecules. Molecules like vitamins that are not soluble in water, such as vitamin A, are
absorbed directly into vessels called lacteals, which belong to the lymphatic
system. They are eventually emptied into a large blood vessel called the superior vena cava,
which delivers them to the heart.
We know that vitamin C, which this question concerns, is soluble in water. So it is not transported via the lymphatic system but instead by the circulatory
system, dissolved in blood plasma. Therefore, the lacteal vessels, lymphatic system, and superior vena cava are not the
correct answers to this question as they transport vitamins that are not soluble in
water.
In contrast, water-soluble vitamins like vitamin C are absorbed from the small
intestine directly into blood capillaries. The capillaries form part of the circulatory system, which carries their contents
through a larger blood vessel called the hepatic portal vein to the liver. The blood containing the water-soluble vitamins will then be delivered via a vessel
called the inferior vena cava to the heart. The heart can then pump blood containing all the vitamins, whether they are soluble
in water or not, to all the cells of the body.
As we are looking specifically at vitamin C, which is soluble in water and therefore
transported from the small intestine via the capillaries to the liver, we can deduce
the vessel that is responsible for delivering it to the body cells. After digestion, vitamin C from strawberry and kiwi juice is provided to the body
through (C) the hepatic portal vein.
