Lecture 3 - Digestive System Flashcards
What does it mean to be soluble
will it dissolve in an aqueous tract
What are the components of the gastrointestinal tract (GI tract) in order
mouth
esophagus
stomach
small intestine
large intestine
caecum*
rectum
What does it mean to be digestible
does the host organism have the enzymes necessary to digest it
What does it mean to be fermentable
do the gut bacteria have the enzymes to break it down
What is a simple digestive system (no caecum)
mono gastric (single stomach)
no caecum
hindgut fermentation
What type of diet is suited for a simple system
nutrient dense and low fibre
What are the two enzymes in the mouth that provide chemical digestion
a-amylase and lingual lipase
What are the components of the stomach
cardia, fundus, body, antrum
What is the nutrient gateway in digestion
the small intestine
What are the three components of the small intestine
duodenum, jejunum, ileum
What is the main site for nutrient absorption and digestion
the small intestine
What are the muscles found in the small intestine
longitudinal and circular muscles
What muscles push the food along in the small intestine
longitudinal muscles
What is the site of fermentation
the large intestine
What is the site of water absorption
the large intestine
Where are short chain fatty acids produced
the large intestine
What is the purpose of villi and microvilli
to increase the surface area for maximal absorption
What is a crypt in terms of villi
villi are the protrusions, crypts are the dips
What is another term for the surface covered in microvilli
brush border
Why do we need gut bacteria
for fermentation purposes
What is a simple digestive system (with caecum)
‘pseudo-ruminant’
hindgut fermenter
all other regions are the same
What type of diet is suitable for a simple system with a caecum
large amounts of fodder and foraging
What is the purpose of a functional caecum
enormous hindgut filled with bacteria
- short chain fatty acids in the large hindgut provide 70% total energy needs for host
What is the signs of energy/nutrient deficiency in pseudo-ruminants
coprophagy (eating own feces)
What is a multiple system digestive system
foregut fermentation
large stomach with 4 regions (reticulum, rumen, omasum, abomasum)
What type of diet is suitable for a multiple system digestive system
high amounts of fodder and forage plant materials
What is unique about ruminant digestion
chew food, bring it back up, chew it, etc.
What are the qualities of the reticulum in ruminants
honeycomb appearance
capture nutrients and trap foreign materials
rich in bacteria
What are the qualities of the rumen in ruminants
largest section*
rich in bacteria
rumen papillae (increased surface area)
What are the qualities of the omasum
reabsorption of water and some electrolytes
filter large particles
What are the qualities of the abomasum
digestive enzymes secreted from gastric glands
the “true stomach” (most similar to the human stomach)
What are the advantages of a ruminant system
vitamin synthesis
non-protein nitrogen used for making protein
What are the disadvantages of a ruminant system
carbs are degraded into gases and lost through eructation
heat production
What is the total collection method
allow animal to adapt to a new diet for 7-21 days
isolate the animal for quantitative analysis
measure intake over 3-10 day period
collect and weigh all feces
analyze the nutrient of interest
What is the equation for the total collection method
apparent digestibility coefficient = (total intake - total feces)/(total intake)
What are some limitations for the total collection method
accuracy in measuring food intake
metabolic cages create anxiety in animals which can cause abnormal behaviour
labour intensive
animals confined with costly equipment
not feasible to capture wild animals
What is the other name for the indicator method
the marker technique
What is the indicator method
adapt animal to test diet containing marker
collect feed and fecal sample
analyze each for marker and nutrient of interest relative to the marker
What is the equation for the indicator method
A = ratio of nutrient/marker in food
B = ratio of nutrient/marker in feces
apparent digestibility coefficient = (A-B/A)
What is the advantage of the indicator method compared to the total collection method
less labour intensive and ideal for wild animals
When calculating apparent digestibility, what is failed to be considered
endogenous secretions (epithelial cells)
bacterial growth in gut (nutrient synthesis)
digestive enzymes (protein secretions)
How to calculate true digestibility
perform digestibility study using a test diet
switch to a diet containing none of the nutrient of interest
analyze the feces after the test diet is cleared
subtract the level of nutrient in feces of zero nutrient from level of nutrient in test diet
What is the equation for true digestibility
A = ratio of nutrient/marker in test diet
B = ratio of nutrient/marker in feces
C = ratio of nutrient/marker in feces after 0 nutrient diet
true digestibility coefficient = A-(B-C)/A
