digestion and absorption Flashcards
What three things can be digested in mammals?
- carbohydrates
- proteins
- Lipids
What is the process of the digestion of carbohydrates?
- It begins in the mouth
- Continues in the duodenum
- Completed in the ileum.
How many enzymes does carbohydrates need to hydrolyses them into monosaccharides?
Carbohydrates required more than one enzyme to hydrolyze them into monosaccharides such as amylase and membrane - bound disaccharidases.
What is the function of amylase in the digestion of carbohydrates?
Amylase is produced by the pancreas and salivary glands. It hydrolyses polysaccharides into the disaccharide maltose by hydrolysing the glycosidic bonds.
What are the membrane - bound disaccharides that are involved in the digestion of carbohydrates and what is their function?
Sucrase and lactase are the membrane - bound enzymes that hydrolyse sucrose and lactose into monosaccharides.
How many enzymes are involved in the digestion of proteins?
Three enzymes that can be used to hydrolyse proteins ( large polymer molecules) are :
- endopeptidases
- exopeptidases
- membrane -bound dipeptidases
What is the function of endopeptidases?
An enzyme that is involved in the digestion of proteins - it hydrolyses peptide bonds between amino acids in the middle of a polymer chain).
What is the function of exopeptidases?
An enzyme that is involved in the digestion of proteins - it hydrolyses peptide bonds between amino acids at the end of a polymer chain.
What is the function of a membrane - bound dipeptidases?
An enzyme involved in the digestion of proteins - it hydrolyses peptide bonds between two amino acids.
What is the process for the digestion of proteins?
Protein digestion starts in the stomach, continues in the duodenum and is fully digested in the ileum.
What are lipids digested by?
They are digested by lipase and the action of bile salts.
Where is lipase produced and what is its function?
Lipase is produced in the pancreas and it can hydrolyse the ester bond in triglycerides to form the monosaccharides and fatty acids.
Where is bile salts are produced and what is its function?
Bile salts are produced in the liver and can emulsify lipids to form tiny droplets, micelles. This increases the surface area for lipase to act on.
What 2 stages does digestion lipids involve?
- Physical ( emulsification and micelle formation )
- Chemical ( lipase )
What is the physical stage that involves the digestion of lipids?
Physical ( emulsification and micelle formation).
- Lipids are coated in bile salts to create an emulsion
- Many small droplets of liquid provides a larger surface area to enable the faster hydrolysis action by lipase