Exchange - Digestion And Absorption

Question 1

What types of enzymes are needed to break down carbohydrates?

Answer 1

1. Amylase
2. Maltase

Question 2

Which enzyme breaks down maltose and where is it found?

Answer 2

• Maltase
• Produced in epithelium cells of small intestine

Question 3

Which enzyme breaks down lactose and where is it found?

Answer 3

• lactase
• produced in epithelial cells in small intestine
• found in walls of small intestine

Question 4

What enzyme breaks down sucrose and where is it found

Answer 4

• sucrase
• found in walls of small intestine

Question 5

Where is sucrase produced?

Answer 5

• produced in epithelial cells in small intestine

Question 6

What reaction breaks down polysaccharides and disaccharides into their monosaccharides?

Answer 6

Hydrolysis

Question 7

Describe how monosaccharides are absorbed into the blood from the lumen of the small intestine

Answer 7

1. Na+ is actively transported to blood from epithelial cell using ATP
2. Na+ concentration gradient is created from lumen into epithelial cell
3. Glucose/ monosaccharide and Na+ are co transported across membrane via facilitated diffusion involving specific carrier protein
4. Glucose/ monosaccharide is transported from epithelial cell into the blood via facilitated diffusion down a concentration gradient

Question 8

Which enzyme breaks down lipids and where is this produced?

Answer 8

• Lipase
• Produced in the pancreas
• Found in the lumen of the small intestine

Question 9

Why are bile salts useful?

Answer 9

• They emulsify lipids
• This increases surface area to volume ratio for lipase to work
• This leads to faster rate of hydrolysis

Question 10

Explain how products of lipid digestion are absorbed

Answer 10

1. Micelles carry monoglycerides and fatty acids to the epithelium of the small intestine
2. At cell surface membrane micelles break down
3. Monoglycerides and fatty acids diffuse into epithelial cells
4. Ester bonds are formed / esterification in smooth endoplasmic reticulum
5. Chylomicrons are formed inside the Golgi apparatus
6. Exocytosis occurs from epithelial cells
7. Chylomicrons are transported from the intestine by the lymph in the lacteal

Question 11

Describe the action of exopeptidases

Answer 11

• hydrolyse peptide bonds from the ends of a protein molecule
• hydrolyse one dipeptide to 2 amino acids

Question 12

Describe the action of endopeptidases

Answer 12

• hydrolyse peptide bonds within a protein molecule
• creates more ends for exopeptidase to hydrolyse

Question 13

Where is exopeptidase produced?

Answer 13

• produced in the pancreas
• found in the lumen of the ileum

Question 14

Where is endopeptidase produced?

Answer 14

• Produced in the pancreas and the stomach
• Found in the stomach and the lumen

Question 15

What is a dipeptidase?

Answer 15

Enzymes that work specifically on dipeptides

Question 16

Where are dipeptidases typically found?

Answer 16

Located in the cell surface membrane of epithelial cells in the small intestine