OESWTE: Digestion and absorption Flashcards
Where is amylase produced?
- Salivary glands
- Pancreas
What disaccharide is starch made from?
Maltose
Where does the digestion of lipids occur?
Small intestine
Explain how lipids are digested:
- Lipids mix with bile salts and are emulsified
- Lipid micelles are hydrolysed by lipase.
- Fatty acids and monoglycerides are a product.
Where is endopeptidase produced?
- Stomach
- Small intestine
Where is dipeptidase produced?
- Stomach
- Small intestine
- Epithelial cell
By what process are amino acids absorbed into the blood?
Co-transport
By what process are monosaccharides absorbed into the blood?
Co-transport
Where does absorption of nutrients occur in mammals?
Ileum
Explain how the ileum is adapted for absorption:
- Ileum wall is covered in villi = thin walls = network of capillaries
In a hydrolysis reaction what are carbohydrates broken down into?
Disaccharides then monosaccharides
In a hydrolysis reaction what are lipids broken down into?
Fatty acids and monoglycerides
In a hydrolysis reaction what are proteins broken down into?
Amino acids
What does amylase digest?
Starch
What is starch made up of?
Two polysaccharides each made from long chains of alpha-glucose molecules
How does amylase digest starch?
- Catalyses hydrolysis reactions that break the glycosidic bonds
- Maltose is produced.
Where does the pancreas release amylase to?
Small intestine.
What are membrane-bound disaccharides?
Enzymes that are attached to the cell membranes of epithelial cells lining the ileum.
What is the role of membrane-bound disaccharides?
Help to break down disaccharides into monosaccharides.
How do membrane-bound disaccharides break down disaccharides into monosaccharides?
Hydrolyse glycosidic bonds.
What does lipase digest?
Lipids
How does lipase digest lipids?
Ester bonds are hydrolysed.
Where is lipase produced?
Pancreas
Where are bile salts produced?
Liver
What is the role of bile salts?
Emulsify lipids
How do lipids being emulsified allow for faster digestion?
Formation of micelles greatly increases the surface area of lipid that the lipase can digest.
Role of endopeptidases:
Hydrolyse peptide bonds and single amino acids at the end of protein molecules.
What are dipeptideases?
Exopeptidases that work specifically on dipeptides.
Role of dipeptidases:
Seperate the two amino acids that make up a dipeptide by hydrolysing the peptide bond between them.
Where are dipeptidases often located?
Cell-surface membrane of the epithelial cells in the small intestine.
How is glucose absorbed across the ileum epithelium into the bloodstream?
Absorbed by active transport with sodium ions via a co-transporter protein.
How do micelles help to move monoglycerides and fatty acids towards the epithelium?
- Micelles break up and reform,
- Releases monoglycerides and fatty acids, allowing them to be absorbed.
Why can monoglycerides and fatty acids diffuse directly across the epithelial cell membrane?
They are lipid-soluble.
How are proteins absorbed across the ileum epithelium into the bloodstream?
- Sodium ions are actively transported out of the epithelial cells into the ileum.
- They then diffuse back into epithelial cells through sodium-dependent transporter proteins, carrying the amino acids with them.
