Digestion and Absorption Flashcards
What is amylase?
A digestive enzyme that catalyses the conversion of starch into maltose
Where is amylase produced?
The salivary glands and the pancreas
What are membrane-bound disaccharides?
Enzymes that are attached too the cell membranes of epithelial cells lining the ileum. They help break down disaccharides into monosaccharides
What is lipase?
Lipase enzymes catalyse the breakdown of lipids into monoglycerides and fatty acids by hydrolysing the ester bond
Where are lipases made?
The pancreas
What are bile salts?
They are produced by the liver and emulsify lipids
How do bile salts help in the break down of lipids?
Bile salts emulsify lipids into small droplets which increases the surface area for lipases to work on. Once the lipid has been broken down, the monoglycerides and fatty acids stick with bile salts to form micelles
What are proteases?
Enzymes that catalyse the breakdown of proteins into amino acids by hydrolysing the peptide bonds
What are endopeptidases?
They hydrolyse the peptide bonds within a protein
Give examples of endopeptidases?
Trypsin and chymotrypsin - synthesised in the pancreas and secreted in the small intestine.
What are exopeptidase?
They hydrolyse the peptide bonds at the end of proteins
Give examples of exopeptidases
Dipeptidases - work specifically on dipeptides. They are located in the cell-surface membrane of epithelial cells in the small intestine
How are monosaccharides absorbed across the ileum epithelium into the bloodstream?
Glucose is absorbed by active transport alongside sodium ions via a co-transporter protein. Fructose is absorbed via facilitated diffusion through different transporter protein
How are monoglycerides and fatty acids absorbed across the ileum epithelium into the bloodstream?
Micelles help to move them towards the epithelium. Because micelles constantly break up and reform they release monoglycerides and fatty acids, allowing they, to be absorbed - they can diffuse directly across the epithelial cell membrane
How are amino acids absorbed across the ileum epithelium into the bloodstream?
Via co-transport in a similar way to glucose and galactose
