Chemical and physical breakdown of foods into smaller and simpler particles
passage of molecules from the gi tract through the mucosal cells in to blood or lymph systems.
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.
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.
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.
What nutrients are absorped?
- - Mono and diglyerides (lipids)
- - sugars (starches and structural CHO)
- -peptides and amino acids (proteins)
- -vitamins, minerals, and water
What is the ultimate goal of eating food?
Nurtirents beyond the level of maintenace can?
support growth, reproduction, movement, depostion of stored nutrients (reserves)
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.
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.
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)
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
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
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
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.
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
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
fermentation takes place before absorptive surfces
See diagrams of stomachs on page 4
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
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