5. Digestion Flashcards
What is digestion
The process by which the larger molecules in the food are hydrolysed into smaller more soluble molecules that can be absorbed by the body
What is the function of the salivary glands
Secrete saliva - a mixture of amylase and water and ions
To digest starch into maltose
What is the function of the pancrease
Produces pancreatic juice - a mixture of enzymes in an alkaline solution, including amylase for release into small intestine
What is the function of the small intestine
Main area of secretion of digestive enzymes and absorption of products
What happens to carbohydrates during starch digestion
Carbohydrase breaks starch up into maltose and then glucose
What happens in starch digestion in the mouth
Begins in the mouth
Salivary glands secret saliva - contains amylase
Catalyses the hydrolysis of starch into maltose
What happens in starch digestion in the small intestine lumen
Duodenum
Pancreatic amylase secreted from the pancreas
Catalyses the hydrolysis of any undigested starch molecules into maltose
What happens to starch digestion on the small intestine membrane
Maltase in the cell membrane of small intestine cells hydrolyse maltose to glucose which is small enough to absorb through the small intestine
How are proteins digestied
Peptidase enzymes hydrolyse proteins into amino acids. Starts in the stomach and then the small intestine
What do exopeptidases do
Hydrolyse peptide bonds between the terminal amino acids to release dipeptides or single amino acids.
Some are produced by the pancreas and some by the small intestine wall
What do endopeptidases do
Hydolyse peptide bonds between amino acids in the central region of the protein forming smaller peptide molecules
Enzymes produced by stomach and pancreas
What do dipeptidases do
Hydolyse peptide bonds holding two amino acids.
Enzymes are membrane bound on the small intestine membrane
What happens in lipid digestion
Starts at duodenum and ends in ileum
Hydrolysed by lipase enzymes produced in pancreas
Hydolyses ester bonds in triglycerides to form fatty acids and glycerol and sometimes monoglycerides
What is the process of lipid digestion
Lipids combine with bile salts produced by the liver = emulsification
Increases surface area so digestion of lipase increases
What is co-transport
Amino acids and glucose are absorbed with Na+ ions.
Specific co-transport carrier proteins take both molecules into the cytoplasm together.
Na+ and glucose have a complementary shape to the binding site on the protein.
Sodium ions then activley pumped through into blood
