Lecture 51- Digestion And Absorption Of Lipids; Absorption Of Vitamins And Minerals Flashcards
What are the three main lipids?
Triglycerides (glycerol + 3 fatty acids)
Cholesterol
Phospholipids
How are lipids provided in diet for domestic animals?
Oils of vegetable or marine origin
Animal fats (tallow, lard, grease)
Dietary lipids must be solubilized in the ________ for digestion and absorption.
Small intestine
What is the function the stomach churning?
Churning breaks lipids into small droplets to increase surface area for enzymes
Mixes lipids, initiates enzymatic digestion
What does gastric lipase do?
Hydrolysis 10% of ingested TAG into glycerol + FFAs
What does the stomach slowly empty into the SI?
Chyme
How does the small intestine digest lipids?
- BILE SALTS EMULSIFY LIPIDS
- PANCREATIC ENZYMES DIGEST DIFFERENT LIPIDS
What does lipase + collapse allow?
Collapse binds to lipase and allows it to digest at lipid-water interface
What does cholesterol ester hydrolase do?
Hydrolyzes cholesterol ester -> free cholesterol + FA + releases glycerol from triglycerides
What is phospholipase A2 activated by?
Trypsin
What does phospholipase A2 hydrolyze?
It hydrolzyes phospholipids into lysolecithin + FA
What do bile salts solubilize products with SI lumen as _______.
Micelles
What does the core of the micelle contain? What is it surrounded by?
Contains products
Surrounded by bile salts
What does NOT diffuse into the enterocyte?
Bile salt
Re-estrified lipids + apoproteins = ________
Chylomicron
What is a chylomicron made up of?
Have cholesterol + TG in core, phospholipids + apoproteins around outside
Need to solubilize for absorption
What are lymphatic capillaries?
Chylomicrons can move between endothelial cells of lymphatic capillaries enter the blood at the thoracic duct
What are the five steps for the absorption of lipids?
- Bile salts solubilize products within SI lumen as micelles (except glycerol)
- Micelles diffuse to brush-border membrane of enterocyte, products released and diffuse into cell
- Products are re-sterilized inside enterocyte to form original compounds
- Re-sterilized lipids are packaged with apoproteins to form chylmoicrons
- Chylmicrons packaged in secretory vesicles and exocytosed across basolateral membrane into lymphatic capillaries
What is NOT solubilized within SI lumen as micelle?
Glycerol
What are 6 abnormalities of lipid digestion and absorption?
- Pancreatic insufficiency
- Acidity of duodenal contents
- Deficiency of bile salt
- Bacterial overgrowth
- Decreased intestinal cells for absorption
- Failure to synthesize apoproteins
What is the pH optimum for lipase?
6
When does a tumor arise?
When there is an over production of gastrin
What is ileal resection ?
No bile salt recycling
What does a lack of Apo B causes ?
Abetalipoproteinemia
Chhylomicrons dont form and cant transport entothyroctes -> lymph