Lecture 14 Fat digestion monogastric Flashcards
1
Q
Name the classifications of Lipids:
A
1- Glycolipids
2-Phosphoglycerides
3-Steroids
4-Eicosanoids
2
Q
Whats fats and oils known as?
A
Triglycerides
3
Q
How many carbons do the 2 essential fatty acids have?
A
18
4
Q
What is denoting different types of fatty acids?
A
the “R”
5
Q
Name Triglycerides:
A
C, H, O
6
Q
Compare triglycerides compared to carbohydrates ?
A
- 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
7
Q
How many glyceride backbone, how many fatty acids in it?
A
3
8
Q
Whats the major lipid class in concentrates
A
-triglycerides (grains)
9
Q
Whats the main lipid storage form in animal tissue?
A
Triglycerides
10
Q
What are triglycerides?
A
Diverse range of fatty acids
11
Q
Whats a major lipid class youd find in forages?
A
Glycolipids
12
Q
Whats the plasma membrane components?
A
- Glycoproteins and glycolipids are
proteins/lipids with short chain
carbohydrates attached on the
extracellular side of the membrane.
13
Q
What are galactolipids a type of?
A
Glycolipids
14
Q
What is the structure of the galactolipids?
A
Glycerol backbone, 2 fatty acids and one or two galactose
15
Q
Whats the name of the 2 essential fatty acids?
A
Linoleic acid
Linolenic acid
16
Q
Whats the structure of Linoleic acid?
A
18;2
17
Q
Whats the structure of Linolenic acid?
A
18;3
18
Q
Give an example of Linoleic acid?
A
Soyabean meal
19
Q
Give an example of Linolenic acid?
A
Linseed oil
20
Q
Wheres the position of the double bonds in linoleic acid?
A
9,12
21
Q
Wheres the position of the double bonds in linolenic acid?
A
9,12,15
22
Q
What is the denoting different types of fatty acids?
A
the “R” group (where its placed)
23
Q
What connects a glycerol to a fatty acid? (glycerol back bone)
A
An ester bond
24
Q
What do triglycerides have more of compared to carbohydrates?
A
-More carbons and hydrogens
-More energy
25
What are triglycerides made up of?
A glycerol and 3 fatty acids
26
How many carbons long are triglycerides?
4-24 carbons long
27
What are the most common types of fatty acids(how many carbons?)
16 and 18 most common
28
What can fatty acids be? (2 classes)
-Saturated
-Unsaturated (Double bonds)
29
Name the major lipid class in concentrates?(grains)
Triglycerides
30
Whats the major lipid storage form in animals tissues?
Triglycerides
31
List the classifications of lipids
-Fats and Oils (Triglycerides)
-Glycolipids
-Phosphoglycerates
-Steroids
-Eicosanoids
32
What are glycoproteins and glycolipids?
They are proteins/lipids with short chain carbohydrates attached on the extracellular side of the membrane
33
What are galactolipids? whats there composition ?
a type of glycolipids.
-Glycerol backbone, 2 fatty acids and 1 or 2 galactose.
34
Name a major lipid in forages?
Galactolipids
35
What are Galactolipids rich in?
Linolenic acid (18;3)
36
What's the role of phospholipids?
Important biological roles :
1-Cell membrane structure, integrity and transport properties
2-Intracellular signalling; hormone transduction
37
What are all membranes?
All membranes are phospholipid bilayers with embedded proteins
38
What do steroid compounds look like?
Multi-ring structure
39
What are good things to know about steroids?
-Insoluable in water
-Present in both plant and animal foods
40
Is steroids a meaningful dietary constituent?
No there not a meaningful dietary constituent in most animals diets
41
What is a major sterol in cholesterol?
Steroids (however cholesterol is only found in animal products)
42
Where is cholesterol manufactured?
In the liver
43
What are essential fatty acids?
fatty acids that the body cannot make enough of to meet the body’s needs
44
What are precursors for longer chain fatty acids?
Linoleic
a-Linolenic
45
Whats the challenges with monogastric digestion? (2)
– Lipids are not water soluble
– Triglycerides too large to be absorbed
46
What's the digestive solution of monogastric digestion of fatty acids?
– Triglycerides mix with bile and pancreatic secretions
* Emulsification and digestion
47
Where does lipid digestion occurs?
1-Mouth
2-Stomach
3-Small Intestine
48
What type of digestion occurs in the mouth?
Lingual lipase
Not very important for mature and growing animals.
Important for neonates and rodents
49
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
50
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
51
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
52
Do fats dissolve in water?
*Fats do not dissolve in water; instead,
they tend to congeal together
53
What does the separation of liquid and water reduce the effectiveness of?
Of a fat digesting enzymes known as lipases
54
What solves the problem of the "separation of lipid and water
reduces the effectiveness of fat-
digesting enzymes, which are known
as lipases"?
Bile
55
What is bile attracted to?
fat and water
56
Where does bile place itself when its going to do its job?
In between fat and water
57
Where does fat remain in water?
Suspended
58
What's this process known as that was just explained?
Emulsification
59
Where bile produced and stored?
Produced in liver
Stored in the gallbladder
60
Whats the animal that has the exception of when it comes to bile being produced and stored?
Except in horses
61
What type of a solution is bile and what is it composed of?(4)
Alkaline solution
Composed of:
-Bile salts
-Cholesterol
-Lecithin
-Bilirubin
62
Name what is responsible for fat emulsification:
Bile (Detergent action)
63
What is emulsification dependent on?
is the dispersion of one phase into another in fine particles
64
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
65
What's an example of fat emulsification?
Emulsification in milk in which its finely divided fat particles are dispersed in water containing proteins
66
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
67
Where is Pancreatic Colipase secreted from?
Secreted from pancreas as
procolipase
68
What activates pancreatic colipase?
Activated (cleaved) by trypsin
69
What does pancreatic colipase anchor?
Anchors lipase to the micelle
70
Whats the ratio for colipase to lipase?
(1:1) ratio
71
What is Lipase?
a globular protein unable to penetrate surface of lipid particles (can only reach surface molecules)
72
What pH is pancreatic lipase activated at?
pH 7
73
How much pancreatic lipase is hydrolysed by what % dietary fat?
80%
74
What is Colipase ?
A co-factor of protein , it anchors lipase to lipid particles
75
Is triglycerides soluble in micelles?
No its insoluble in micelles
76
Is Lipolysis products soluble in micelles?
Soluble in Micelles
77
What can sometimes occur in gallbladder?
Gallstones
78
What are the 2 VERY important secretions that are ESSENTIAL for digestion of triglycerides
1) Bile salts
2) Pancreatic Lipase
79
Whats the role of pancreatic lipase?
Removes 2 fatty acids from
triglycerides leaving a monoglyceride
80
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
81
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
82
What are the protein-coated lipid droplets called when lipid digestion is occurring?
Chylomicrons
83
What are chylomicrons used for?
– particles for transport of lipids to liver & adipocytes
84
Whats the average composition of chylomicrons?
-TG = 84%
-Cholesterol = 8%
-PL= 8%
-Apolipoproteins= 2%
85
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
86
Whats the exception of lipid absorption (Chylomicrons)?
Poultry
87
What are blood lipids transported as?
Lipoproteins
88
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
