Lipid Digestion and Absorption

Question 1

Sites of Lipid Digestion

Answer 1

Mouth, stomach, small intestine

Question 2

Lipid Mouth Mechanical Digestion

Answer 2

Mastication and emulsification (breaks down big lipid droplets to small ones)

Question 3

Lipid Mouth Chemical Digestion

Answer 3

Lingual lipase. Hydrolases medium and long chain triglycerides (products: diglycerides, mono-glycerides and fatty acids)

Question 4

2 enzymes that act in stomach

Answer 4

Lingual and gastric lipase (chief cells in stomach). Acid stable. Hydrolyses ester bonds in medium and long chain triglycerides (products diacylglycerides and fatty acids)

Question 5

mechanical digestion in intestine

Answer 5

emulsification. Increase surface area of droplets. Peristalsis and bile salts (detergents)

Question 6

Pancreatic Chemical Digestion

Answer 6

pancreatic lipase and pancreatic co-enzymes. Hydrolyses bonds monoglycerol and fatty acids

Question 7

Cholesterol Esterase

Answer 7

Hydrolyses cholesteryl esters to cholesterol and fatty acids

Question 8

Phospholipase A2

Answer 8

phospholipid to lyso-phospholipid by removing 1 fatty acid. Require bile salts

Question 9

Lysophospholipase

Answer 9

Removes remaining fatty acids at C1. Glycerlphosphoryl base, excreted or absorbed

Question 10

Lipid Digestion at Brush Border

Answer 10

Micelle

Question 11

Mixed micelle outline

Answer 11

Micelle (externally hydrophilic, internally lipophilic) made of bile salts, free fatty acids, phosphipids, 2-monoglycerol and free cholesterol (lipid digestion products). Digest long fatty acid chaind (medium and small don’t need it). HYdrphilic outer layer is formed by bile salts’ detergent properties

Question 12

Fate of free fatty acids and monoglycerides

Answer 12

Absorbed into smooth endoplasmic reticulum, synthesise triglyceride. Grouped with choloresteol esters, free cholesterol, phospholipidsand vitamins to form chylomicrons. Move to golgi apparatus tomove across basolateral membrane

Question 13

How chylomicrons move in golgi apparatus

Answer 13

Move into exocytotic vessels. Move to basolateral aspect of enterocyte membrane vesticles fuse with enterocyte membrane. Exocytosis pushes chylomicrons into extracellular space near lymph

Question 14

Absorption of fat soluble substances depend on

Answer 14

Bile salts, normal pancreatic function and normal intestinal cells

Question 15

What % of dietary fat is utilised

Answer 15

95%

Question 16

What % starch is digested efficently

Answer 16

70-90 %

Question 17

Keratin and cellulose % digested

Answer 17

0%