What is the movement of digested food substances through the walls of the small intestine into the blood or lacteal called?

• A. Absorbtion
• B. Digestion
• C. Assimilation
• D. Ingestion

Answer: (A)

Absorption is the process by which digested nutrients pass through the wall of the small intestine into the bloodstream or into the lacteals of the lymphatic system. Once digestion has broken down large food molecules into smaller ones, these nutrients must cross the intestinal lining to be carried to cells throughout the body. Glucose, amino acids, and minerals mainly enter the blood, while fats are absorbed into lacteals and then join the bloodstream via the lymphatic system. This is different from digestion, which is breaking down food; from assimilation, which is using nutrients by body cells; and from ingestion, which is simply taking food into the digestive system. Note that the common spelling is absorption, not absorbtion.