Mechanisms of Digestion and Absorption (Nursing)

00:01 So now let's talk about the mechanisms of digestion and absorption of the different biomolecules.

00:09 Recall that digestion is going to break down our ingested foods into their chemical building blocks and it is only these molecules that are actually small enough to be absorbed through the wall of the small intestine.

00:26 Digestion is a catabolic process that is going to break down these macromolecules down into monomers.

00:35 These monomers are then small enough to be absorbed through the wall of the intestine.

00:42 There are intrinsic and accessory gland enzymes that are involved in digestion.

00:48 And these enzymes are going to carry out a chemical reaction known as hydrolysis.

00:54 And hydrolysis water is added in order to break down chemical bonds.

01:02 So first looking at absorption.

01:05 Absorption is a process of moving a substance from the lumen of the gut into the body.

01:12 Because of tight junctions between the cells, molecules cannot pass between cells and must rather pass through the cells.

01:23 Materials will enter the cells through the apical membrane of these cells or the lumen side and exit through the basolateral membrane or the blood side.

01:36 Lipid molecules can be absorbed passively through the membrane, but most polar molecules have to be absorbed by active transport.

01:46 Most of our nutrients are absorbed before the kind reaches the last part of the small intestine or the ileum.