ACTIVITY 1: The Food Journey
-
How does the food change in consistency and form?
- In order for our food to be effectively digested and absorbed, it must first undergo a transformation in consistency and shape known as ingestion, which involves putting food into the alimentary canal through the mouth. There, the food is chewed and combined with saliva, which has enzymes that start to break down the food's carbohydrates, expand its surface area, and enable the production of a bolus that is an appropriate size. After food is broken up and physically churned to expose more of its surface area to digestive fluids, it exits the mouth as an acidic "soup" known as chyme; this process is initiated by the tongue and pharyngeal muscles. Once food has been digested, it enters the circulation and is absorbed, mostly in the small intestine, where its nutrients are put to use. The last stage of digestion, defecation, is the removal of undigested elements from the body as feces. -
How could the body absorb the nutrients from the foods we eat?
- The duodenum, jejunum, and, ileum, which is coated with millions of finger-like projections called villi and microvilli that are linked to a network of capillaries, are where nutrients are primarily absorbed. There, the mucosa's epithelial cells absorb the majority of nutrients from the alimentary canal's lumen into the circulation (the epithelial tissue is specialized for absorption). Lacteals absorb lipids, which are then carried to the circulation by lymphatic arteries (the subclavian veins near the heart). Nutrients enter the bloodstream in this way.