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Digestion
Chemical and physical breakdown of foods into smaller and simpler particles
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Absorption
passage of molecules from the gi tract through the mucosal cells in to blood or lymph systems.
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What is the purpose of the GI tract? does digestion = absoprtion
- - assimilation of nutrients
- - exclusion of unnecessary or harmful substances (not everything we consume is good for us)
- - some nutrients can be digested but not absorped.
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Comparative nutrition. What is comon in digestion in animals
- - All have common elements, principals and processes of digestive physiology. All animals have similiar processes.
- - All intake of food through the mouth, digestion of feed, absorption of nutrients, transport of absorbed nutritents to the site of metabolism, excretion of waste products, ultimate goal is maitenace.
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What is digested from feed? What are they used for?
proteins - polypeptide to peptides and amino acids. Animal will use amimo acids to create protieins
starches- sugars absorped and used for energy
structural carbohydrates (fibers) -
triglyerides - fatty acids, mono and digylcerols. Broken down by the enzyme lipase.
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What nutrients are absorped?
- - Mono and diglyerides (lipids)
- - sugars (starches and structural CHO)
- -peptides and amino acids (proteins)
- -vitamins, minerals, and water
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What is the ultimate goal of eating food?
Maitenance
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Nurtirents beyond the level of maintenace can?
support growth, reproduction, movement, depostion of stored nutrients (reserves)
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Difference among species in digestive physiology is due to degree? How do they differ?
eating - specialized mouth structures. type of teeth (grinding cutting), presence/absence of teeth.
digestive tract. diet is based on digestive physiology. Structures, functions from the start of the digestive tract to the end.
absorption of nutrients. - transports and other mechanisms
metabolism of nutrients. - maintenace, production/work.
excretion of waste products.
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How are animals different in removing wastes.
- - Feeces, typically stuff not used by the animal
- - Urine, excetion of excess nitrogen.
- Ureotelic (urea, mammals), is the inbewteen. takes a fair bit of energy and water.
- Uricotelic (uric acid), birds and land reptiles. Doesnt take very much water but does take lots of energy to go to uric acid
- Ammonotelic (ammonia), fish. Needs lots of water (is very toxic) depends on how much water, can be acid.
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Classification based on the structures present. What are the 3 types of classifications. Provide an example
- -Monogastric (chicken)
- - Non ruminant (or monogastic) herbivorie (have very high diets and fibre)
- - Ruminant (have specialized able to use fibre effeciently, cows)
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Classification based on type of diet. Examples. Are these classifications strict
- Herbivore plants (sheep, deer)
- Carnivoire (moslty meat, bobcat)
- Omnivorie (meat/plants, humans and pigs have GI tract for both meats and plants)
No can be somewhat blurry
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Mongastrics. Examples. Description
- - Pig, fowl, dog, mink, fish and monkeys.
- - Simplest digestive system
- -limited capacity (volume to body size)
- - limited/variable microbial action
- -limited fibre digestion
- -adapted to highly digestable diets (grains, digestible plant material)
- see pic 3 lecture
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Non ruminant herbivore. Examples. despcriptions
- -horse, rabbit, guinea pig, hamster
- -feeding requirements bewteen monogastric and ruminant.
- -functional ceccum.
- -large intestine plus ceccum conatin microbes (fibre digestion produces VFA's leads to energy, microbes also lead to vitamin B synthesis)
- -fermentation occurs after much of the absorptive sections of the GI tract
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Horses... Good hind gut fermenters?
Horses provide a good enviro for microbes to survive and ferment. Known as hind gut fermenters. Thats why they can eat hay and such.
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Ruminant. Examples. descriptions.
- -cattle, sheep, bison, deer, and elk
- -mouth, no upper incisor or canine teeth
- -four stomach compartments (rumen where most of the fermentation happens, reticulum, omasum, abomasum)
- -more space greater volume. 9x digestive capacity of the human
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What are the microorganism in a cow? How many? What do they do? What is the relationship? How is it different then in a non ruminant herbivorie
- Bacteria - 25-80 billion
- protozoa - 200,000 - 5,000,000 /ml
allows digestion of fibre - production of VFAs, also able to produce vitamin B's and essential amino acids
Symbiotic relationship.
fermentation takes place before absorptive surfces
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See diagrams of stomachs on page 4
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Why does man have a small ratio of intestinal: body length? and cows a long
humans have 10:1. shows that we are omnivoires. Shows that we eat meat which is quite easy to break down/absorb. Compared to cattle 20:1 have a large intestinal because it is harder to break down plants
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Body Lenght: gut length in Erbivories? Why such low ratios?
- Ostrich 1:13
- Rhea 1:8
- Chicken 1:4
- Emu 1:4
- Cassowary 1:3
birds neeed to have effiecient DT. They have reverse parstalosis so are able to move food back and forth over the DT
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