Anatomy and Physiology of Digestion

Question 1

Digestion

Answer 1

physical, chemical, and enzymatic processes that prepare a feedstuff for absorption

Question 2

physical digestion

Answer 2

mastication (chewing)

peristalsis (smooth muscle contraction)

Question 3

chemical digestion

Answer 3

acid (HCl) in stomach or abomasum

Question 4

enzymatic digestion

Answer 4

enzymes to break down chemical bonds
produced in various locations in the GI tract
- mouth, pancreas, small intestine, bacteria in rumen, cecum or colon

Question 5

types of digestive systems

Answer 5

monogastric, avian, ruminant, pseudo-ruminant, hind gut fermentation

Question 6

monogastric

Answer 6

one simple stomach
carnivores - cats, dogs
omnivores - humans, pigs, avian too

Question 7

herbivore fermentation strategies

Answer 7

pregastric, pseudo ruminant, post gastric

Question 8

ruminant

pre-gastric

Answer 8

"polygastric" 
characteristics
-slower digestion
carbohydrates are fermented to VFAs
-acetate, propionate, butyrate 
VFAs absorbed and transported to liver

Question 9

acetate

Answer 9

2 carbon

Question 10

propionate

Answer 10

3 carbon

Question 11

butyrate

Answer 11

4 carbon

Question 12

microbial protein

Answer 12

high biological value
rumen microbes break down plant protein and make microbial protein
they then pass down digestive tract, die and are digested
major AA source for ruminants

Question 13

true ruminants

Answer 13

4 chambered stomach
rumination
cattle, sheep, goats, deer, buffalo, antelope, gazelles, giraffe

Question 14

pseudoruminant

Answer 14

3 chambered stomach (rumen+reticulum combined also have glandular HCl stomach)
function like a true ruminant
rumination fermentation of CHO to VFAs

Question 15

post gastric (hind gut) fermentation

Answer 15

microbial protein lost in feces

energy obtained from absorption of VFAs

Question 16

steps of digestion

Answer 16

prehension
mastication
salivation
deglutition

Question 17

prehension

Answer 17

bring food into mouth

Question 18

mastication

Answer 18

chewing

Question 19

salivation

Answer 19

salivary gland secretion

Question 20

deglutition

Answer 20

swallowing

Question 21

rumination

Answer 21

regurgitation
reinsalvation
remastication
redeglutition

Question 22

mouth

Answer 22

contains organs of:
prehension (teeth tongue)
mastication (teeth jaws)
salivation (salivary glands)
deglutition (palate throat epiglotis)

Question 23

saliva

Answer 23

contains:
amylase - starch digestion
bicarbonate - buffering

Question 24

esophagus

Answer 24

tube connecting mouth to stomach
function:
-transports ingesta from mouth to stomach
-peristalsis - moves food to stomach
-lower esophageal sphincter - prevents acid reflux

Question 25

stomach

Answer 25

``` functions: -mixing and storage -mucus secretions -HCl very strong acid environment to denature proteins and be an acid barrier to microbes -enzymes - lipase - triglyceride - pepsin - protein pyloric sphincter regulates passage of digesta to intestines ```

Question 26

small intestine

Answer 26

major site of enzymatic digestion, absorption, and intestinal juices many segments provides surface area for absorption (folds villi microvilli)

Question 27

liver

Answer 27

secretion of bile | "detergent" to emulsify fat

Question 28

pancreas

Answer 28

secretes: - bicarbonate - digestive enzymes (lipase, protease, amylase)

Question 29

segments of the small intestine

Answer 29

duodenum, jejunum, ileum

Question 30

duodenum

Answer 30

short segment buffers and enzymes enter via bile and pancreatic secretions

Question 31

jejunum

Answer 31

main site of absorption

Question 32

ileum

Answer 32

connects to large intestine

Question 33

large intestine

Answer 33

functions: -fermentation -absorption of water, VFAs, minerals, B vitamins microbial protein lost in feces some species practice cecotrophy (rabbits)

Question 34

digestion of proteins

Answer 34

hydrolyzed to AA by peptidases and absorbed and transported in blood

Question 35

digestion of carbohydrates: monogastrics

Answer 35

amylase cleaves starch chains into monosaccharides (glucose) and some disaccharides (maltose) intestinal disaccharides complete digestion into monosaccharides which can then be absorbed

Question 36

digestion of carbohydrates: ruminants

Answer 36

fermentation to VFA | VFA absorbed from rumen into blood

Question 37

digestion of lipids

Answer 37

fat and fat soluble vitamins mostly triglycerids in diet hydrolyzed to fatty acids monoglycerides absorbed and reformed into triglycerides packaged w/ protein complexes "lipoproteins" transported to bloodstream via lymphatic system @ thoracic duct

Question 38

avian digestive system

Answer 38

``` monogastric type enzymatic digestion no teeth crop proventriculus ventriculus (gizzard) ceca cloaca ```

Question 39

crop

Answer 39

esophageal distention which serves to store moisten and soften ingesta

Question 40

proventriculus

Answer 40

glandular stomach HCl and enzymes ingesta passes thru quickly, little digestion occurs

Question 41

ventriculus (gizzard)

Answer 41

stones, grit particle reduction b/c no teeth

Question 42

ceca

Answer 42

paired structures | fermentation

Question 43

cloaca

Answer 43

common opening for digestive and reproductive systems

Question 44

agents of rumen fermentation

Answer 44

microbes! | bacteria, protozoa, archea

Question 45

reticulum

Answer 45

honeycomb, hardware stomach | ingesta moves freely btwn rumen and reticulum

Question 46

rumen

Answer 46

the major fermentation chamber | lined w/ papillae

Question 47

omasum

Answer 47

manyplies, dry contents, function not clear

Question 48

abomasum

Answer 48

``` true or glandular stomach similar to nonruminant stomach acid secretion (HCl) ```

Question 49

esophageal groove

Answer 49

``` milk fed calves folds of reticulum which can close to form a tube allowing liquid to bypass the fore stomachs stimulated by suckling preruminant stage of life similar to monogastrics ```

Question 50

factors affecting rumen development

Answer 50

age, diet, VFA

Question 51

eructation

Answer 51

belching

Question 52

rumen stratification

Answer 52

top layer = gas middle layer = fiber mat bottom layer = liquid

Question 53

vitamin products of rumen fermentation

Answer 53

vit K and B