5 - Digestion Flashcards
Define the term ‘digestion’
Process by which large molecules in food are hydrolysed into smaller more soluble molecules that can be absorbed by the body
Name the components of the digestive system
Oesophagus, salivary glands, liver, stomach, pancreas, small intestine, large intestine, rectum
State the function of the salivary glands
Secrete salive - mixture of amylase, water and ions
State the function of the pancreas
Produces panreactric juice - mixture of enzymes in alkaline solution - amylase, proteases, lipases - for release into small intestine
State the function of the small intestine
Digestion complete by enzymes + bile(liver). Absorption of products of digestion occurs here
How is starch digested in the mouth
Salivary glands secrete salica which contains amylase.
Hydrolyses starch ——> maltose
How is starch digested in the small intestine lumen
Pancreatic amylase hydrolyses any undigested starch to maltose
Where is maltase found and what is it’s function?
Brush border of small intestine
Maltase hydrolyses maltose —–> glucose
Describe the function of exopeptidases
Hydrolyses peptidse bonds between terminal amino acids
Describe the functiond of endopeptidases
Hydrolyses peptide bonds between amino acids in the central region of the protein
Describe the function of dipeptidases
Hydrolyses peptide bonds holding two amino acids of a dipeptide
Which molecules are absorbed in the gut via co-transport?
Amino acids and monosaccharides (e.g. glucose) with Na+ ions
How does a co-transport protein recognise sodium ions and glucose molecules but nothing else?
Na+ and glucose have complementary shape to binding site on the protein, which has a specific tertiary structure
Describe the absorption of glucose (same for amino acids)
From the gut into epithelial cells via active transport - co-transport with Na+ ions.
From epithelial cells into blood via facilitated diffusion
Describe the absorption of lipids
Lipase hydrolyses lipids into fatty acids + glycerol
Emulsification with bile slats of fatty acids + glycerolto micelles
Simple diffusion of micelles into epithelial cells
Triglycerides in epithelial cells into chylomicrons
Chylomicrons packaged into vesicles by golgi then exocytosis into blood
