Lecture 14 Fat digestion monogastric Flashcards
Name the classifications of Lipids:
1- Glycolipids
2-Phosphoglycerides
3-Steroids
4-Eicosanoids
Whats fats and oils known as?
Triglycerides
How many carbons do the 2 essential fatty acids have?
18
What is denoting different types of fatty acids?
the “R”
Name Triglycerides:
C, H, O
Compare triglycerides compared to carbohydrates ?
- Many more carbons and hydrogens
compared to CHO - More energy compared to CHO
- All contain glycerol and 3 fatty acids
- Fatty acids 4-24 carbons long
- 16 and 18 most common
- Saturated or unsaturated double bonds
How many glyceride backbone, how many fatty acids in it?
3
Whats the major lipid class in concentrates
-triglycerides (grains)
Whats the main lipid storage form in animal tissue?
Triglycerides
What are triglycerides?
Diverse range of fatty acids
Whats a major lipid class youd find in forages?
Glycolipids
Whats the plasma membrane components?
- Glycoproteins and glycolipids are
proteins/lipids with short chain
carbohydrates attached on the
extracellular side of the membrane.
What are galactolipids a type of?
Glycolipids
What is the structure of the galactolipids?
Glycerol backbone, 2 fatty acids and one or two galactose
Whats the name of the 2 essential fatty acids?
Linoleic acid
Linolenic acid
Whats the structure of Linoleic acid?
18;2
Whats the structure of Linolenic acid?
18;3
Give an example of Linoleic acid?
Soyabean meal
Give an example of Linolenic acid?
Linseed oil
Wheres the position of the double bonds in linoleic acid?
9,12
Wheres the position of the double bonds in linolenic acid?
9,12,15
What is the denoting different types of fatty acids?
the “R” group (where its placed)
What connects a glycerol to a fatty acid? (glycerol back bone)
An ester bond
What do triglycerides have more of compared to carbohydrates?
-More carbons and hydrogens
-More energy
What are triglycerides made up of?
A glycerol and 3 fatty acids
How many carbons long are triglycerides?
4-24 carbons long
What are the most common types of fatty acids(how many carbons?)
16 and 18 most common
What can fatty acids be? (2 classes)
-Saturated
-Unsaturated (Double bonds)
Name the major lipid class in concentrates?(grains)
Triglycerides
Whats the major lipid storage form in animals tissues?
Triglycerides
List the classifications of lipids
-Fats and Oils (Triglycerides)
-Glycolipids
-Phosphoglycerates
-Steroids
-Eicosanoids
What are glycoproteins and glycolipids?
They are proteins/lipids with short chain carbohydrates attached on the extracellular side of the membrane
What are galactolipids? whats there composition ?
a type of glycolipids.
-Glycerol backbone, 2 fatty acids and 1 or 2 galactose.
Name a major lipid in forages?
Galactolipids
What are Galactolipids rich in?
Linolenic acid (18;3)
What’s the role of phospholipids?
Important biological roles :
1-Cell membrane structure, integrity and transport properties
2-Intracellular signalling; hormone transduction
What are all membranes?
All membranes are phospholipid bilayers with embedded proteins
What do steroid compounds look like?
Multi-ring structure
What are good things to know about steroids?
-Insoluable in water
-Present in both plant and animal foods
Is steroids a meaningful dietary constituent?
No there not a meaningful dietary constituent in most animals diets
What is a major sterol in cholesterol?
Steroids (however cholesterol is only found in animal products)
Where is cholesterol manufactured?
In the liver
What are essential fatty acids?
fatty acids that the body cannot make enough of to meet the body’s needs
What are precursors for longer chain fatty acids?
Linoleic
a-Linolenic
Whats the challenges with monogastric digestion? (2)
– Lipids are not water soluble
– Triglycerides too large to be absorbed
What’s the digestive solution of monogastric digestion of fatty acids?
– Triglycerides mix with bile and pancreatic secretions
* Emulsification and digestion
Where does lipid digestion occurs?
1-Mouth
2-Stomach
3-Small Intestine
What type of digestion occurs in the mouth?
Lingual lipase
Not very important for mature and growing animals.
Important for neonates and rodents
What type of digestion occurs in the stomach?
Gastric lipase
* Little to none
* Churning creates a course lipid emulsion
* Fat slows the release of food from the stomach
What type of digestion occurs in the small intestine?
Pancreatic lipase
* Performs 90% of all lipid digestion
* Primarily performs hydrolysis
* Mix bile salts to convert coarse emulsion into micelles
A bit about fat digestion:
*Fats do not dissolve in water; instead,
they tend to congeal together
*This separation of lipid and water
reduces the effectiveness of fat-
digesting enzymes, which are known as lipases
*Bile solves the problem
*It is attracted to fat and water
*Bile molecules therefore place
themselves in between the fat and water
*Fat remains suspended in water
*Also called emulsification
Do fats dissolve in water?
*Fats do not dissolve in water; instead,
they tend to congeal together
What does the separation of liquid and water reduce the effectiveness of?
Of a fat digesting enzymes known as lipases
What solves the problem of the “separation of lipid and water
reduces the effectiveness of fat-
digesting enzymes, which are known
as lipases”?
Bile
What is bile attracted to?
fat and water
Where does bile place itself when its going to do its job?
In between fat and water
Where does fat remain in water?
Suspended
What’s this process known as that was just explained?
Emulsification
Where bile produced and stored?
Produced in liver
Stored in the gallbladder
Whats the animal that has the exception of when it comes to bile being produced and stored?
Except in horses
What type of a solution is bile and what is it composed of?(4)
Alkaline solution
Composed of:
-Bile salts
-Cholesterol
-Lecithin
-Bilirubin
Name what is responsible for fat emulsification:
Bile (Detergent action)
What is emulsification dependent on?
is the dispersion of one phase into another in fine particles
What does the emulsification of fats allow to happen?
Allows high surface area for the fatty particles and increases the rate of any chemical reaction
What’s an example of fat emulsification?
Emulsification in milk in which its finely divided fat particles are dispersed in water containing proteins
Whats the process of Lipid digestion (3)
1-Bile salts emulsify lipids
2-Pancreatic lipase acts on triglycerides
– Triglycerides> 2 monoglyceride + 2 fatty acids
3-Pancreatic colipase
– Activated by trypsin
– Interacts with triglyceride and pancreatic lipase
* Displaces bile to allow recycling
* Improves activity of pancreatic lipase
Where is Pancreatic Colipase secreted from?
Secreted from pancreas as
procolipase
What activates pancreatic colipase?
Activated (cleaved) by trypsin
What does pancreatic colipase anchor?
Anchors lipase to the micelle
Whats the ratio for colipase to lipase?
(1:1) ratio
What is Lipase?
a globular protein unable to penetrate surface of lipid particles (can only reach surface molecules)
What pH is pancreatic lipase activated at?
pH 7
How much pancreatic lipase is hydrolysed by what % dietary fat?
80%
What is Colipase ?
A co-factor of protein , it anchors lipase to lipid particles
Is triglycerides soluble in micelles?
No its insoluble in micelles
Is Lipolysis products soluble in micelles?
Soluble in Micelles
What can sometimes occur in gallbladder?
Gallstones
What are the 2 VERY important secretions that are ESSENTIAL for digestion of triglycerides
1) Bile salts
2) Pancreatic Lipase
Whats the role of pancreatic lipase?
Removes 2 fatty acids from
triglycerides leaving a monoglyceride
What’s the process of lipid absorption?
- Mixed micelles move to the intestinal
epithelium (enterocytes) and release
contents near cell - The bile salts are re-absorbed further
down the gastrointestinal tract (in the
ileum), transported to the liver, and finally recycled and secreted back into the digestive tract
What occurs in the enterocyte when lipid absorption is occurring?
- Newly formed triglycerides accumulate as ‘lipid droplets’ at the endoplasmic reticulum
– Coated with a protein layer - Stabilizes lipids for transport in lymph and blood (aqueous environment)
- Protein layer is needed to allow the lipid to be soluble in plasma
– Glycerol and short chain fatty acids directly enter mesenteric blood
What are the protein-coated lipid droplets called when lipid digestion is occurring?
Chylomicrons
What are chylomicrons used for?
– particles for transport of lipids to liver & adipocytes
Whats the average composition of chylomicrons?
-TG = 84%
-Cholesterol = 8%
-PL= 8%
-Apolipoproteins= 2%
Where are lipid absorption (Chylomicrons) absorbed from?
Chylomicrons absorbed from enterocytes into lacteals (lymph vessels)
– Ultimately enter blood via thoracic duct
* Most long chain fatty acids absorbed into lymphatic system
Whats the exception of lipid absorption (Chylomicrons)?
Poultry
What are blood lipids transported as?
Lipoproteins
Explain the overview of fatty acid uptake:
- Short- and medium-chain fatty acids
– Enter portal blood directly from enterocytes
– Bound to albumin in blood - Albumin–FFA complex
– Oxidized in liver or elongated and used for
triglyceride formation - Long-chain fatty acids
– Form chylomicrons
– Drain into the lymphatics via the lacteal in
mammals (no lacteal in avian small intestinal villi)
– Enter bloodstream at the thoracic duct - Upstream from liver
- Slow entry into the blood
