Digestive Tract Physiology Flashcards
breaking
down process is termed
Digestion
the passage of the digested nutrients through the
mucous membrane is called
Absorption
Nutritional requirement of animals and their ability to utilize feedstuffs are greatly dependent on their digestive tract anatomy and physiology
Digestive Tract Physiology
Physical digestion occurs thru mastication of food to smaller particles to
increase the surface area for exposure to digestive enzymes.
Starch is hydrolyzed to maltose by enzymatic digestion of salivary amylase
Oral Cavity
Stores ingested feed and meters ingesta into small intestine in amounts that
intestinal digestion can accommodate.
Stomach
Major site of digestion and absorption in simple non-ruminants
Small intestines
Three segments of small intestine
Doudenum, jejunum,ileum
Major site of nutrient absorption
Jejunum
Pancreas serves as a major source of digestive enzymes that degrade the
following:
- CHONS: trypsin, chymotrypsin
- CHO: amylase
- LIPIDS: lipase
A complex ecosystem of anaerobic microorganisms further degrades and
metabolizes undigested residues entering the large intestines
Large intestines
is metabolized to indole and skatole, which gives
the characteristic odor of the feces
Trytophan
Species Differences in Specific Aspects of Gastrointestinal Anatomy and Physiology
Strict carnivores
Omnivores
(minks, cats) have a short intestinal tract and rapid transit time
of ingesta through the GIT because of the higher digestibility if their meat-based
diet.
Strict carnivores
(swine) tend to have a long small intestine and an enlarges hindgut
with a much more significant microbial population of some fiber digestion
Omnivores
Avian Digestive System
Mouth
Foregut
Mouth
Beaks and tongue
replace lips and teeth with its shape, size and length varying with type
of diet consumed.
Beaks
is also adapted to type of food consumed
Tongue
Foregut
Gizzard and Proventriculus
(muscular part) performs function of mammalian teeth. The churning
action of the gizzard and grit (small stones) it contains grind feed into smaller
Gizzard
(glandular part) is where HLC and digestive enzymes are
secreted.
Proventriculus
Differs from a simple non-ruminant because it has a large, compartmentalized
stomach
Microbes that inhabit the large stomach mostly accomplish digestion, rather
than enzyme the animal produces itself
Ruminants
Absence of upper incisions, instead dental pads are present. A large gap between
the incisors of molars allow cattle to harvest and chew a large amount of fibrous
feeds.
Teeth are primarily for grinding and tongue is used to gather and grasp grasses.
Saliva contains sodium bicarbonate to keep rumen at a proper neutral pH for
good bacterial growth.
Mouth and Teeth
4 chambers
Rumen
Reticulum
Omasum
Abomasum
A fermentation vat that contains an immense microbial
population of bacteria (protozoa, fungi and yeast) that ferment
the ingested feeds.
Rumen
Also produces large quantities of gasses mainly carbon dioxide
and methane, which are removed by a process called
Eructation
“chewing the cud” is a characteristic feature of all ruminants
Rumination
Traps foreign materials such as nails, wire and stones, which
accumulate in this compartment that eventually punctures the
small intestine
Reticulum
- Regulates flow of ingested by acting as a sieve or filter thru its
membranous leaves. - Ingested feeds must be thoroughly degraded to smaller
particles in order to pass thru the omasal leaves thereby
promoting maximum fermentation efficiency
Omasum
- Site of secretion of gastric juices such as HCl and proteolytic
enzymes. - Acidity in this compartment allows digestion of microbial
protein, which serves as the major source of amino acids for
ruminants.
Abomasum
Include horses, rabbit, guinea pig, zebra, elephant and hippopotamus
Non- Ruminants Herbivores
No important domesticated species of non-ruminant foregut fermenters.
Foregut fermenters
Equids are examples
Colon fermenters
Example is rabbit
They have low digestibility of fiber so they can adapt by selectively separating and
excreting indigestible fiber and retaining the more digestible non-fiber contents for
fermentation in the cecum.
Cecal fermenters
