Digestion And Absorption

Question 1

Carbohydrate digestion

Answer 1

carbohydrates are consumed in food through the mouth
salivary glands release amylase which breaks starch into disaccharide, maltose- by hydrolising the glycosidic bonds.
salts also released by salivary glands to maintain a neutral pH.
stomach contains hydrichloric acid denaturing the amylase prventing further hydrolysis.
the food is then passed into the small intestine which contains pancreatic juices containing pancreatic amylase. this continues the hydrolysis of remaining starch into maltose.
the epithelial lining of the ileum contains maltase which hydrolyses the maltose into alpha glucose.

Question 2

Lipids

Answer 2

Lipase enzymes catalyse the breakdown of lipids into fatty acids and monoglyverides
This involves the hydrolysis of the ester bonds in lipids
Lipsses are made in pancreas and secreted into the small intestine where they act
Bile salts are released by the liver and emulsify lipids this causes the lipids to form small droplets which increases the surface area for lipases to work on.
Once broken down by lipases the monoglyverides and fatty acids stick with the bile salts to form micelles which help.the products of digestion to be absorbed

Question 3

Proteins

Answer 3

Endopeptidases- act to hydrolyse peptide bonds from the inside within a protein
Exopeptidases- hydrolysis peptide bonds on the ends of a protein and remove single amino acids
Dipeptidases- exopeptidases the specifically work on dipeptides separating the two amino acids by hydrolysis of the peptide bond between them.

Question 4

Absorption of products of digestion - monosaccharides

Answer 4

Monosaccharides- glucose absorbed with sodium ions by a cotransporter
Galactose absorbed in the same way with the same co transporter
Fructose absorbed via facilitated diffusion

Question 5

Monoglycerides and fatty acids

Answer 5

Micelles help move them towards the epithelium
Because they constantly break up and reform they can release the monoglycerides and fatty acids
Allowing them to be absorbed monoglycerides and fatty acids are lipid soluble so can move across the epithelial cell membrane