Lipid Digestion

Question 1

What are the 4 most predominant dietary lipids?

Answer 1

TAG’s, Phospholipids, Cholesterol and Fat-soluble Vitamins.

Question 2

Where does digestion begin?

Answer 2

In the oral cavity, where lipids are exposed to lingual lipases.

Question 3

What secretes lingual lipases?

Answer 3

Serous glands.

Question 4

Serous glands.

Answer 4

Salivary glands located on both sides of oral cavity towards back of tongue.

Question 5

Lingual Lipases

Answer 5

Generate non-esterfied FA from dietary fats through lipolysis.

Question 6

Esterfication

Answer 6

Formation of esters from reactions between acids and alcohols.

Question 7

Esters

Answer 7

Organic compounds that react with water to produce alcohols/in/organic acids.

Question 8

Alcohol

Answer 8

An organic compond containing hydroxyl groups.

Question 9

Acids

Answer 9

Chemicals that form hydrogen ions in solutions.

Question 10

Where are ester bonds fond in lipids?

Answer 10

Between FA and glycerol.

Question 11

What are non-esterfied FA?

Answer 11

Molecules isolated from glycerol, released by lipase action.

Question 12

What does lipase convert TAGS to after ester hydrolysis?

Answer 12

Diacylglycerols or Monoacylglycerols with free FA

Question 13

What does phospholipid ester hydrolysis yield?

Answer 13

FFA and lysophospholipids.

Question 14

What does cholesterol ester hydrolysis yield?

Answer 14

Cholesterol and FFA.

Question 15

Cholesterol Ester

Answer 15

A cholesterol with a fatty acid bound by ester bonds.

Question 16

What two ways do Enterocytes use to uptake MAG and FFA?

Answer 16

Diffusion and Protein-mediated transport.

Question 17

When does enterocyte diffusion occur?

Answer 17

When luminal FFA concentration exceeds intracellular.

Question 18

What happens to FFA when they enter enterocytes?

Answer 18

Processing in various organelles via FA binding proteins.

Question 19

What protein is used for cholesterol uptake into enterocytes?

Answer 19

Niemann-Pick C1-like 1.

Question 20

What do Niemann-Pick C1-like 1. form in the PM?

Answer 20

Lipid rafts.

Question 21

Process of cholesterol enterocyte uptake by Niemann-Pick C1-like 1….

Answer 21

Cholesterol binds NTD binding site, exposing CTD, with interacts with proteins facilitating clathrin recruitment.

Question 22

What happens after cholesterol interaction with Niemann-Pick C1-like 1.?

Answer 22

Internalised, transporting to endocytic compartments, releasing and transporting to other organelles.

Question 23

What happens to MAG in the ER?

Answer 23

Esterfied with FFA by enzymes, forming DAGS that can be used to synthesize phospholipids.

Question 24

What happens to cholesterol in the ER?

Answer 24

They are esterfied.

Question 25

Why are MAG and CHOL esterfied in the ER after enterocyte absorption?

Answer 25

Favours entry of more hydrolysed intraluminal products, due to reduced intracellular concentraitons.

Question 26

What happens to newly synthesised ER lipids?

Answer 26

Form cytosolic lipid droplets which can be either stored or secreted.

Question 27

Lipid Droplets

Answer 27

Intracellular organelles specialise in energy storage in the form of TAGS and sterol esters.

Question 28

General structure of Lipid Droplets?

Answer 28

They have a phospholipid monolayer, with a core of triglycerides and cholesterol esters.

Question 29

What happens to lipid droplets in fasting states?

Answer 29

Mobilised and secreted from enterocytes.

Question 30

What does lipid droplet mobilisation require?

Answer 30

TAG hydrolysis with FA mobilisation to ER for TAG re-synthesis, followed by secretion with lipoproteins.

Question 31

What happens to ER synthesised lipids proceeding lipid droplet mobilisation?

Answer 31

Packaged into chylomicrons.

Question 32

Structure of CM?

Answer 32

Phospholipid monolayer, surrounded by ALP B48, with a TAG and cholesteryl ester core.

Question 33

What happens to CM after their assembly?

Answer 33

Released from basolateral side, entering general circulation at the thoracic duct.