Lipid Digestion

Question 1

How are lipids digested

Answer 1

Lipids are digested by lipase (produced in the pancreas) into fatty acids and glycerol. The ester bond found in triglycerides is hydrolysed.​

Question 2

How is the surface area of lipids increased to aid lipase action

Answer 2

Lipids are split into micelles by bile salts produced by the liver. This is called emulsification.

Question 3

Why do vitamins and minerals not require digestion?

Answer 3

They are small molecules, so can pass through the intestinal lining without being broken down further

Question 4

List the adaptations of the ilium for absorption of the products of digestion. Explain the purpose of each adaptation​

Answer 4

Folded to form villi 1mm long​ - Increase surface area for diffusion​

Thin wall of epithelial cells​ - Reduce diffusion distance​

Rich network of capillaries​ - Maintain a steep diffusion gradient​

Villi possess microvilli​ - Increase surface area for diffusion​

Question 5

What is the first step of lipid digestion

Answer 5

Bile salts emulsify triglycerides into droplets called micelles.​ The monoglycerides and fatty acids remain associated with the micelle.​

Question 6

What is the second step of lipid digestion

Answer 6

Micelles meet the ilium wall and break down releasing the monoglycerides and fatty acids.​ These are non polar and move by diffusion into epithelial cells.​

Question 7

What is the third step of lipid digestion

Answer 7

monoglycerides and fatty acids are transported to the endoplasmic reticulum where they recombine to form triglycerides.​

Question 8

What is the fourth step of lipid digestion

Answer 8

triglycerides move to the Golgi apparatus and associate with cholesterol and lipoprotein to form structures called chylomicrons.​

Question 9

What is the fifth step of lipid digestion

Answer 9

Chylomicrons move out of cells by exocytosis and move into lacteals found in the lymphatic system​