Lecture 3 - Digestive System

Question 1

What does it mean to be soluble

Answer 1

will it dissolve in an aqueous tract

Question 1

What are the components of the gastrointestinal tract (GI tract) in order

Answer 1

mouth
esophagus
stomach
small intestine
large intestine
caecum*
rectum

Question 2

What does it mean to be digestible

Answer 2

does the host organism have the enzymes necessary to digest it

Question 3

What does it mean to be fermentable

Answer 3

do the gut bacteria have the enzymes to break it down

Question 4

What is a simple digestive system (no caecum)

Answer 4

mono gastric (single stomach)
no caecum
hindgut fermentation

Question 5

What type of diet is suited for a simple system

Answer 5

nutrient dense and low fibre

Question 6

What are the two enzymes in the mouth that provide chemical digestion

Answer 6

a-amylase and lingual lipase

Question 7

What are the components of the stomach

Answer 7

cardia, fundus, body, antrum

Question 8

What is the nutrient gateway in digestion

Answer 8

the small intestine

Question 9

What are the three components of the small intestine

Answer 9

duodenum, jejunum, ileum

Question 10

What is the main site for nutrient absorption and digestion

Answer 10

the small intestine

Question 11

What are the muscles found in the small intestine

Answer 11

longitudinal and circular muscles

Question 12

What muscles push the food along in the small intestine

Answer 12

longitudinal muscles

Question 13

What is the site of fermentation

Answer 13

the large intestine

Question 14

What is the site of water absorption

Answer 14

the large intestine

Question 15

Where are short chain fatty acids produced

Answer 15

the large intestine

Question 16

What is the purpose of villi and microvilli

Answer 16

to increase the surface area for maximal absorption

Question 17

What is a crypt in terms of villi

Answer 17

villi are the protrusions, crypts are the dips

Question 18

What is another term for the surface covered in microvilli

Answer 18

brush border

Question 19

Why do we need gut bacteria

Answer 19

for fermentation purposes

Question 20

What is a simple digestive system (with caecum)

Answer 20

‘pseudo-ruminant’
hindgut fermenter
all other regions are the same

Question 21

What type of diet is suitable for a simple system with a caecum

Answer 21

large amounts of fodder and foraging

Question 22

What is the purpose of a functional caecum

Answer 22

enormous hindgut filled with bacteria
- short chain fatty acids in the large hindgut provide 70% total energy needs for host

Question 23

What is the signs of energy/nutrient deficiency in pseudo-ruminants

Answer 23

coprophagy (eating own feces)

Question 24

What is a multiple system digestive system

Answer 24

foregut fermentation large stomach with 4 regions (reticulum, rumen, omasum, abomasum)

Question 25

What type of diet is suitable for a multiple system digestive system

Answer 25

high amounts of fodder and forage plant materials

Question 26

What is unique about ruminant digestion

Answer 26

chew food, bring it back up, chew it, etc.

Question 27

What are the qualities of the reticulum in ruminants

Answer 27

honeycomb appearance capture nutrients and trap foreign materials rich in bacteria

Question 28

What are the qualities of the rumen in ruminants

Answer 28

largest section* rich in bacteria rumen papillae (increased surface area)

Question 29

What are the qualities of the omasum

Answer 29

reabsorption of water and some electrolytes filter large particles

Question 30

What are the qualities of the abomasum

Answer 30

digestive enzymes secreted from gastric glands the "true stomach" (most similar to the human stomach)

Question 31

What are the advantages of a ruminant system

Answer 31

vitamin synthesis non-protein nitrogen used for making protein

Question 32

What are the disadvantages of a ruminant system

Answer 32

carbs are degraded into gases and lost through eructation heat production

Question 33

What is the total collection method

Answer 33

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

Question 34

What is the equation for the total collection method

Answer 34

apparent digestibility coefficient = (total intake - total feces)/(total intake)

Question 35

What are some limitations for the total collection method

Answer 35

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

Question 36

What is the other name for the indicator method

Answer 36

the marker technique

Question 37

What is the indicator method

Answer 37

adapt animal to test diet containing marker collect feed and fecal sample analyze each for marker and nutrient of interest relative to the marker

Question 38

What is the equation for the indicator method

Answer 38

A = ratio of nutrient/marker in food B = ratio of nutrient/marker in feces apparent digestibility coefficient = (A-B/A)

Question 39

What is the advantage of the indicator method compared to the total collection method

Answer 39

less labour intensive and ideal for wild animals

Question 40

When calculating apparent digestibility, what is failed to be considered

Answer 40

endogenous secretions (epithelial cells) bacterial growth in gut (nutrient synthesis) digestive enzymes (protein secretions)

Question 41

How to calculate true digestibility

Answer 41

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

Question 42

What is the equation for true digestibility

Answer 42

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