Digestive System Flashcards
what are the 7 parts of the gastrointestinal tract (in order)
- mouth
- esophagus
- stomach
- small intestine
- large intestin e
- caecum
- rectum
what does the GI tract refer to
the digestive tract
what does the digestive system refer to
digestive system refers to the GI tract and associated organs (liver, pancreas, gallbladder)
what is solubility
determining whether something is soluble within the aqueous environment of the digestive tract
what is digestibility
determining whether the host organism has the enzymes necessary to digest CHO
what is fermentability
determining whether gut bacteria has the enzymes necessary to break down CHO
what are the example organisms that dont have a caecum
human, pig, cat, dog
what are the key features of a simple system w/o a caecum?
- monogastric
- non-functional caecum
- suited for a dense, low fibre diet
how long is the human gut?
16 feet
what digestive process occurs within the oral cavity?
- food is chewed
- food is mixed with saliva
what digestive processes occur in the stomach
- food becomes chyme
- gastric glands secrete gastric juice (h2O, electrolytes, HCL, enzymes)
what is the gastric juice made of
water, electrolytes, HCL, and enzymes
what are the four regions of the stomach
cardia, funds, body, antrum
what is the volume of the stomach
empty: 50mL
full: 1.5L
what is the pH of the stomach
2
what digestive processes occur in the small intestine?
- main site for nutrient digestion and absorption
- chyme acidity is neutralized by pancreatic juice
- food is digested by pancreatic juice and bile acids
what is pancreatic juice
bicarbonate
what are the three parts of the small intestine?
duodenum
jejunum
ileum
what is the surface area of the small intestine
30m2
within the small intestine, what is the intestinal motility controlled by
intestinal motility is controlled by longitudinal and circular muscles
what digestive processes occur in the large intestine
- site of fermentation
- production of short chair fatty acids (volatile fatty acids)
- site for water absorption
what gives the small intestine such a large surface area
- kerckring folds
- vili (and crypts)
- microvilli
transport mechanism used for various nutrients depends on what three factors?
- solubility
- concentration gradient
- molecular size
how much bacteria is generally in the large intestine
10^12/g content
why are bacteria important
-fermentation of non-digestible CHO (CHO fermentation produces many compounds ie- lactate)
what are three examples of animals with a simple system with a functional caecum
horse, rabbit, hamster
what are the key features of simple systems with a functional caecum
- pseudo-ruminant
- functional caecum (fermentation pouch)
- suited for a diet with large amounts of fodder
what is the purpose of a functional caecum?
- enormous handout (20-30L capacity) filled with bacteria
- provides 70% of total energy needs for host
- site for the production of vitamins
what is the sign of an energy or nutrient deficiency within animals with a SSFC
eating own feces
in horses, which nutrients are absorbed in the small intestine
- glucose
- amino acids
- fatty acids
in horses, which nutrients are absorbed within the large intestine and caecum
- lactic acid
- amino acids
- SCFA
what animals have ruminant systems
cattle
sheep
goats
what are the key features of ruminant system
- divided into 4 regions (reticulum, rumen, omasum, abomasum)
- system highly suited for animals that eat a high quantity of fodder
describe the reticulum
- honeycomb appearance in order to capture nutrients and trap foreign materials
- rich in bacteria (fermentation vat)
describe the rumen
- largest section of the stomach
- rich in bacteria
- large SA
- food is mixed and partially broken down, and stored temporarily
describe the omasum
- resorption of water and electrolytes
- filters large particles
describe the abomasum
-digestive enzymes secreted from gastric glands
in the ruminant system, where does fermentation take place
fermentation takes place before entering the intestine (foregut digestion)
- nutrients produced by bacteria then become available for digestion and absorption by the ruminant
what are the advantages to the ruminant system
- vitamin synthesis
- non-protein nitrogen used for making protein
what are the disadvantaged to the ruminant system
- carbs degraded into gasses and are lost through eructation (burping)
- heat production
what ate the distinct features of an avian system
- beaks and claws are important for breaking up food into smaller pieces that birds can swallow
- rapid digestion (birds can starve is deprived of food for even a short time ie-hours)
what is the crop of the avian system
- enlarged area of the esophagus
- well developed in most species
- temporary storage for food
- food is softened here ( and often yacked up to feed the kids)
describe the two-chamber stomach of the avian system
- granular portion= proventriculul (gastric enzymes are secreted)
- muscular portion = gizzard (grind tough foods)
what is the ceca in the avian system
minor site of bacterial fermentation
what is a cloaca
where the digestive, urinary, and reproductive systems meet
describe what happens with the total collection method
- animal has to first adapt to the diet over a 7-21 day period
- isolate animal for quantitative analyses
- measure intake over 3-10 days
- collect and weight all feed
- analyze for nutrient of interest
what is the equation used when calculating the apparent digestibility coefficient?
(total intake - total feces) / (total intake)
describe the indicator method
“marker technique”
- requires either an internal (natural component of the feed) or external (a component added to the feed)
- collect feed and fecal sample
- analyze each for marker and nutrient of interest
what are the characteristics of the markers used for the indicator method
- non absorbant
- must not affect or be affected by GIT
- must mix easily with feed
- easily and accurately measured in samples
what is the equation used when calculating apparent digestibility coefficient?
(A-B)/A
what is the advantage to using the indicator method?
less labour intensive, ideal for wild animals
apparent vs true digestibility
apparent digestibility under-estimated true digestibility
what is not considered when calculating apparent digestibility?
- endogenous secretions
(epithelial cells- fatty acids released from dying intestinal cells) - bacterial growth in gut
(nutrient synthesis- biotin produced by gut bacteria ) - digestive enzymes
(protein secretion- digestive enzymes released by cells)
how do you find true digestibility
- perform digestibility study using a test diet
- switch to diet containing none of the nutrient of interest (zero nutrient diet)
- analyze feed after test diet is cleared
- subtract level of nutrient in feed of animals fed the zero nutrient diet from the test diet
what is the equation used when calculating true digestibility?
[A-(B-C)]/ A
A= ratio of nutrient/marker in test diet B= ratio of nutrient/marker in feces C= Ratio of nutrient/marker in feed after zero nutrient diet
