digestion and absorption of carbohydrates, lipids, and proteins. Flashcards
where does the digestion of carbohydrates take place in?
in the mouth and in the small intestine.
explain the whle process of starch ( carbohydrates) being digested.
- Salivary glands produce the enzyme salivary amylase, which hydrolises the glycosidic bond of starch, thus turning it into maltose.
Any remaining starch molecules, pass intot he small intestine, where they get hydrolised by pancreatic amylase.
in the lumen of the ileum, cells in the epithelial lining produce maltase ( membrane-bound disaccharidase)
This maltase, then hydrolises the glycosidic bonds of maltose into glucose
Where can sucrose mainly be found?
in fruits.
describe how sucrose can be hydrolised.
- It is hydrolised in the lumen of the ileum( small intestine), by sucrase ( membrane bound disacharide).
what is sucrose hydrolised into?
it is hydrolised into glucose and fructose.
describe how Lactose can be hydrolised.
it is hydrolised in the lumen of the small intestine, by lactase ( membrane bound disaccharide).
where can lactose be found?
in dairy products.
what is lactose hydrolised into?
glucose and galactose.
describe the digestion of lipids.
it takes place in the small intestine.
Firstly, it mixes with bile salts( produced by the liver), in order to undergo emulsification.
The lipids then form micelles.
the micelles are then hydrolised by lipases ( enzymes secreted by pancreas).
Micelles then become glycerol and fatty acids.
where are bile salts produced?
In the liver.
Where is lipase produced?
in the pancreas.
where does the digestion of proteins occur?
It begins in the stomach.
Although most protein digestion, happens in the small intestine.
What are the 3 types of protease?
endopeptidase, exopeptidase, and dipeptidase.
describe how a protein is digested.
1.endopeptidase ( found in both stomach and small intestine) hydrolises peptide bonds in the central region of a protein molecule, in order to produce polypeptides.
2.exopeptidase ( found in the small intestine) then hydrolises peptide bonds at the end of polypeptide chains, to create dipeptides.
3. membrane bound dipeptidase enzyme ( found in intestine epithelial cells), hydrolises dipeptides into amino-acids.
Describe the full mechanism of absorption for micelles.
- Micelles move to the surface of epithelial cells, where they eventually break down , to release MONOGLYCERIDES, and FATTY ACIDS.
- since these are non-polar, they diffuse into the epithelial cells.
- once in the cell, the endoplasmic reticulum, then turn monoglucerides and fatty acids, into triglycerides.
- these then raavel to the golgi apparatus, whjere they get packaged into lipoproteins.
- these lypoproteins then move out of the epithelial cells, into the lyphatic capillaries, VIA EXOCYTOSIS.
- once in the blood stream, the lipoproteins get hydrolised back into triglycerides.
