The nutrients extracted from the food you eat are absorbed into the blood stream
ID: 3517300 • Letter: T
Question
The nutrients extracted from the food you eat are absorbed into the blood stream through the walls of your small intestines. If you examined the interior of the tube of the small intestines, you would find that it was folded, and if you looked with a microscope at the layer of cells lining the hollow center, you'd find that this layer was shaped into millions and millions of small hairs (called vili). And if you looked even closer, you'd discover that the exposed surface of every cell on those small hairs was formed into even tinier hairs called microvili. Explain all of this elaboration of the interior surface of the small intestines.
Explanation / Answer
The small intestine absorbs almost 90% of nutrients from the food we consume.
The interior walls of the small intestine are tightly wrinkled into projections called circular folds that greatly increase their surface area. Microscopic examination of the mucosa reveals that the mucosal cells are organized into finger-like projections the villi, which further increase the surface area. Each square inch of mucosa contains around 20,000 villi. The cells on the surface of the mucosa (epithelial cells)also contain finger-like projections of their cell membranes known as microvilli, which further increase the surface area of the small intestine. It is estimated that there are around 130 billion microvilli per square inch in the mucosa of the small intestine. All of these wrinkles and projections help to greatly increase the amount of contact between the cells of the mucosa and chyme to maximize the absorption of vital nutrients.Villi are small, finger-like projections that extend into the lumen of the small intestine. Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border.