Digestion and Absorption Flashcards
digestion
obtaining nutrients essential for body processes from food
includes acquisition and dividing of foods into smaller parts
digestion tract function
prepare nutrients for absorption
store nutrients
build useful products
reject unused and broken down residue
absorption
crossing the epithelium and entering the blood
must have absorption to utilize nutrients
why do animals digest food?
food not ingested in a suitable state
physical nature of feed determines
-gathering apparatus for uptake
-type of digestive system required for digestion
carnivores
meat eaters
simplest digestive tract (monogastric)
herbivores
plant eaters
most complex digestive tract
ruminant or monogastric and hind gut fermenters (horses)
omnivores
plant and meat eaters
intermediate digestive tract
feed utilization steps
- selection: selection of appropriate food relies on all 5 senses, also learned aversions
- prehension: process of getting food into mouth, claws and paws, lips, tongue, teeth
3.mastication: chewing, divides food particles, mixes with saliva - deglutition: swallowing
- digestion: physical changes-chewing, swallowing, crushing, peristaltic potions,, chemical changes- enzymes, bacteria, microorganisms, digestive juices
6.absorption: crossing epithelium, utilization of nutrients
7.circulation: transport of nutrients to site of storage and use via blood or lymph - metabolism: cell level utilization- anabolism(tissue growth) and catabolism (tissue breakdown)
- excretion: body voids material- defecation, urination, sweat, exhale, wearing off cells
avian digestive system
lack of teeth- lack of digestion in mouth
gizzard-super muscular, can breakdown tough feed and crop- enlargements of esophagus
proventriculus- like a stomach
small intestine
ceca- between small and large intestine, where fermentation takes place of forage
mouth
functions: take in food, prehension differs with species, taste, chew (mastication), mix with saliva
mastication: physical reduction of feed to increase surface area
carnivores- large canines and incisors for tearing and little chewing
herbivores- specialized molars for chewing and grinding
saliva: add moisture to feed, aid in chewing, aid in swallowing
amylase- digestive enzyme that starts to breakdown simple sugars in the feed
esophagus
muscular tube
pharynx to stomach (cardia)
begins with striated (voluntary) –> ends with smooth muscle (involuntary)
dogs and ruminants striated throughout
angle of attachment in horses discourages regurgitation
reticulum
“honeycomb”
-where food first drops, grinding and transfer
-traps objects “hardwear disease”
reticular groove
-young ruminants
-transfer milk from esophagus to abomasum (bypass rumen system to true stomach)
-non functional after weaning
reticular groove “esophageal groove”
-young ruminants
-transfer milk from esophagus to abomasum (bypass rumen system to true stomach)
-non functional after weaning
-muscular contractions close the groove
rumen
covered in papilla -increased surface area for absorption and function
fermentation vat- anaerobic breakdown of feed (without oxygen)
largest compartment >40 gallons
ecosystem of microbes
-bacteria, protozoa, and fungi
-produce volatile fatty acids (VFAs) and microbial cell protein
rumen development
only abomasum developed in newborn ruminant
-little fermentative capability: size, musculature, microbial population
development requires solid feed and microbes
2-3 months of age
influence of diet on rumen development
milk only diet: papillae is very smooth
milk and hay: more developed papillae
milk and grain: ^^
fermentation
occurs primarily in reticulum and rumen
rumen microbial population: symbiotic relationship (both benefiting)
majority bacteria, then protozoa, with fungi and yeast in smaller amounts
products of fermentation: VFA, gas (methane, carbon dioxide), heat, microbial crude protein, B vitamins, vitamin K
rumination
re-chewing coarse material
-diet dependent
6-10 hours per day
steps in the process:
-regurgutation
-remastifaction
-reensalivation
-reswallowing
reduces particle size and increases salivary flow
eructation
expelling gases produced from microbial fermentation
peak fermentation = 12-30L of gas/hr
failure to expel gases= bloat
omasum
“many plies”, pages of a book
-moves particles from rumen to abomasum
-continue to grind roughage
-aborption of water
abomasum
“true stomach”
functions exactly like a monogastric stomach
glandular portion of stomach
uses hydrochloric acid and other enzymes to digest feed
stomach
ruminant: 4 compartments (3/4 of abdominal cavity)
monogastric (non ruminant): one compartment, size varies
glandular stomach
stomach in monogastric, abomasum in ruminants
function:
-mixing action
-acid secretion
-enzyme secretion
digested food leaves the stomach as chyme
-mixture of food and digestive juices
stomach anatomy
regions:
-esophagel (non glandular)
-cardiac (mucus)
-fundic (mucus, HCl (parietal cells), pepsin (chief cells)
-pyloric (mucus)
small intestine
similar arrangement and function for monogastric and ruminnat animals
-3 segments
duodenum: attached to stomach (pyloric sphincter), primary site of digestion, begins absorption
jejunum: middle segment, absorption
ileum: final segment, absorption, attaches to cecum via ileo-cecal valve
large intestine
3 segments: cecum, colon, rectum
function
-fermentative digestion (no enzyme secretions, relies on microbes washed out of small intestine)
-absorption of water, VFAs, vitamins, and minerals (no absorption of lipid (fatty acids) or protein (amino acids)
