explain how sugars, amino acids, and lipids are absorbed from the lumen of the small intestine?

Answer 1

The small intestine is the site where most of the nutrients from ingested food are absorbed. It is covered in wrinkles which are called plicae circulara. These are considered permanent folds in the wall of the organ. They are distinct from rugae which are considered non-permanent or temporary fold which allow for distention and contraction.

From the Plicae circulara project microscopic finger-like pieces of tissue called villi.

The purpose of these wrinkles and projections is to increase surface area for absorption of nutrients. Each villus is covered in microvilli, which increase the surface area manyfold. Each villus contains a lacteal and capillaries. The lacteal absorbs the digested fat into the lymphatic system which will eventually drain into the circulatory system. The capillaries absorb all other digested nutrients.

The surface of the cells on the microvilli are covered with a brush border of proteins which helps to catch a molecule-thin layer of water within itself. This layer, called the "unstirred water layer," has a number of functions in absorption of nutrients.

The digestion of proteins into peptides and amino acids principally occurs in the stomach but some also occurs in the small intestine. The small intestine is where the most chemical digestion takes place:

peptides are degraded into amino acids
lipids (fats) are degraded into fatty acids and glycerol
carbohydrates are degraded into simple sugars (e.g., glucose)

Answer 2

The intestinal mucosa is greatly folded. The folds are called villi. The whole intestinal linnig is richly supplied with blood capillaries. The digested food called as chyle contains simple sugars like glucose, amino acids, minerals, fatty acids and glycerol ,water etc. All micromolecules except fatty acids and glycerol are absorbed by the blood capillaries by simple diffusion. Thus sugars, amino acids etc make directly their way into blood. The fattyacid and glycerol molecules are not taken by blood. They are absorbed by Lacteals------lymphatic vessels. The lacteals carry lipid particles in the lymph circulation but finally these lipid particles are poured into the blood stream in the body.

Answer 3

should be in your text bk, but:
sugars and amino acids are absorbed by the cells lining the small intestine by diffusion and active uptake. these then pass into the blood stream and then on to wherever else. lipids are absorbed the same way but go into a different tube in the microvilli as they are too big to go diresctly into the blood. the cells are micro villi.

Answer 4

Here's some hints to add to what you already know:
You want to mention diffusion and active transport.
Lipids can pass through plasma membranes into cells.
Water soluble molecules (amino acids and sugars) can't pass through the plasma membrane so they need to use channels and pores to enter the cell.
Think about surface area (look up villi).

Answer 5

Part of doing homework is doing your research. Try reading your textbooks, or an encyclopedia.

Answer 6

Damn, i think i might fail Home ec. and Biology....
I really should know that kinda crap....

O.K. Just found out from my biology teacher... by diffusion and active transport. (!?!)

Answer 7

It should be right there in your textbook

Answer 8

No! Sorry! I don't know!