Chapter 10 Flashcards
Digestion
The breakdown of large molecules to simpler, smaller chemical compounds that can be absorbed
Digestion is the…?
Preparation for absorption.
It’s complete when molecules are small enough to be absorbed.
The digestion of food is accomplished by which three methods?
Physical or mechanical, chemical and enzymatic
What is the physical or mechanical action of digestion?
Chewing (mastication)
Grinding in the GI Tract (Avians)
Omassum - ruminants
Digestive turbulence
What is the chemical action of digestion?
HCL will be produced and start or initiate the digestion of proteins in the stomach
Bile acids or salts will be produced by the liver and will cause lipid digestion and absorption
What is the enzymatic action of digestion?
Primary! Most important!
Proteins - all enzymes are proteins
Specific substrates (lactase for lactose, etc)
Narrow pH (2, 7-7.5) stomach then SI
Cofactors are needed (minerals and vitamins)
Function by hydrolysis via use of water
Absorption
A set of processes that result in passage of small molecules from lumen of gut through cells of GI tract to bloodstream
The three intestinal modifications that increase surface area are?
Folds - 3x
Villi - 30x
Microvilli (brush border) - 600x
What are the different types of absorption?
Passive Diffusion
Active Transport
Facilitated Diffusion
Phagocytosis
Passive Diffusion
Passage of substance from lumen into intestinal cell due to concentration gradient
Move from a high concentration in the lumen to a low concentration to the cell
No energy required
Active Transport
Important for many amino acids and nutrients
Absorption from lumen to intestinal cell against a concentration gradient
Low concentration in the lumen to high concentration in the cell
Requires a carrier protein and energy
The carrier protein will interact with the substrate and “pump” the substance to the cell
Facilitated Diffusion
Similar to active and passive.
Similar to active except it’s not moving against a concentration gradient and no energy is required
High [C] in the lumen and Low [C] in the cell
A carrier protein is required and will interact with the substrate to move the substance
Phagocytosis
Is unlike any other absorption.
Absorption when part of villi cell breaks off and engulfs a nutrient.
No digestion is required. Only absorption of large molecules; antibodies formed shortly after birth.
24 - 48 hr process after this the gut closure process starts.
Very important in livestock and new born mammals due to transfer for globulin found in the colostrum in the mom and newborn.
Colostrum is the first form of milk
Steps of Digestion
Prehension Mastication Salivation Swallowing Stomach SI LI Dedication Urination
