Digestion
Enzymes
Other random facts
Absorption
More random facts
Carbohydrases
Amylase - They break down starch into maltose. They are produced in salivary glands and the pancreas and are active in the ileum and the mouth.
Lipase - They break down lipids and produce monoglycerides, glycerol and fatty acids. They are produced in the pancreas and are active in the Ileum.
Maltase - They break down maltose into two glucose molecules. They are produced in the ileum and are active in the ileum (they are bound to the ileum walls, meaning that they can be used again).
Sucrase - They break down sucrose into a glucose and a fructose molecule. They are produced in the ileum and are active in the ileum (they are bound to the ileum walls, meaning that they can be used again).
Lactose - They break down lactose into a glucose molecule and a galactose molecule. They are produced in the ileum and are active in the ileum (they are bound to the ileum walls, meaning that they can be used again).
Proteases
Dipeptidase - They break down dipeptides into amino acids. They are produced in the stomach, pancreas and the ileum. They are found in the stomach and bound to the ileum wall (so that they can be used again).
Endopeptidase - They break down central peptide bonds to produce smaller polypeptides. They are produced in the stomach and are active in the stomach.
Exopeptidase - They break down terminal peptide bonds to produce dipeptides and amino acids. They are produced in the stomach and are active in the stomach.
Lipids
Bile salts are produced by the liver, and emulsify the lipids, causing them to form smaller droplets.
Since the lipids are in smaller droplets, there is a larger surface area for the enzyme lipase to act on.
This means that the formation of monoglycerides and fatty acids greatly increases.
When formed, the monoglycerides and fatty acids stick with the bile salts to form small structures called miscelles. Micelles help the products of lipid digestion to be absorbed by moving them towards the epithelium and then releasing them.
Monosaccharides - monosaccharides like glucose are absorbed through the process of co-transportation. Sodium travels out of the cell through the process of active transport, leaving a low concentration of sodium in the cell. Through a co-transporter protein, the glucose then diffuses into the cell with sodium.
Amino acids are absorbed in the same way that glucose is.
Bile doesn't contain enzymes.
Carbohydrases act on glycosidic bonds, proteases act on peptide bonds and lipases act on ester bonds.
Bile is an alkaline meaning it neutralises stomach acid, denaturing proteases, but providing the optimum pH for intestinal/pancreatic enzymes.
Foods move down the oesphagus through the process of peristalsis.
The ileum has walls made from epithelial cells, that are arranged in villi to increase surface area for absorption.
The epithelial cells have microvilli on them to increase area for absorption even further.
The gall bladder is where bile is stored.
The colon is where water is absorbed.
The ileum has one cell thick walls, providing a smaller diffusion distance.
Chemical digestion is done with chemicals (enzymes), whereas physical digestion is done physically (churning).