Lecture 5 Part 1 Flashcards
what are the roles of GIT secretions
- lubricate and protect through saliva and mucus
- alter pH
- things that do digestion, enzymes
- things that assist with digestion, bile
why does the GIT need to be protected through saliva and mucus
- so don’t tear holes in GIT
- easier swallowing
- protect pH so no ulcers
what are some examples of enzymes that alter pH
- HCl in stomach to create acidic
- bile salts in SI to make basic
how does bile assist with digestion
emulsify fats so they are more easily digested
what is special about the digestive enzymes
- very specific in target substrate
- very specific in where in substrate they attach and react
what is an enzyme
- substance produced by living organisms that acts as catalyst to bring about specific reaction
- breaks bonds
- proteins
what are the ways to describe an enzyme
- source (ex: salivary amylase)
- substrate
- end product
where is the location of enzymes and microbes in ruminants
- microbial fermentation in rumen
- followed by digestive enzyme action in small intestine
- ruminants live off what microbes produce
- collective work of enzymes
location of enzymes and microbes in non-ruminant
- digestive enzymes attack feed prior to microbial fermentation
- enzymes working before fermentation
benefits of microbes in ruminants
- microbial fermentation allows cattle to thrive on fibrous feed
- high quality dietary protein & starch degraded
- low quality dietary protein improved by microbes
where in the body are the most nutritionally significant enzymes produced
pancreas and walls of small intestine
why in some species are the salivary enzymes present but not important
because the enzymes are rapidly denatured in stomach
what does cavital mean
secreted
- produced in one area and then to work in another
what are some cavital enzymes
- salivary
- gastric
- pancreatic
what does intestinal mean
- not secreted
- in intestine
- imbedded within a cell or brushed border
what are some intestinal enzymes
- membrane (brush border)
- intracellular (mucosal cells)
what does low pH in stomach do to enzymes
denature
what are the types of enzymes
- carbohydrase
- proteolytic
- lipolytic
carbohydrase
- breaking carbs
- most generic
what are the two kinds of carbohydrase
- amylolytic: digest starch and simple sugars
- cellulytic: digest cellulose and other nonstarch polysaccharides
polysaccharides
breaks down cellulose
amylolytic
- source= salivary/pancreatic
- cleaves the alpha 1, 4 glycosidic bonds
- cavital glycosidase
glycosidase
enzyme that breaks bonds between 2 carbons
what does amylase digest
amylose into glucose
lactase digests
lactose into glucose and galactose
sucrase digests
sucrose into glucose and fructose
mannase digests
mannose into glucose
what is intestinal glycosidases
- part of brush border
- not secreted
- source= imbedded in cell
what is special for cellultyic enzymes
- only microbes produce this enzyme
what do mammals need to assist with to digest structural polysaccharides
microbes
why is sucrase not found in ruminants
microbes break sugar down first so no sugars reach intestine
- must take into consideration amount included in milk replacer
why is pancreatic amylase production low in ruminants
microbes break starch down first so not starch will reach intestine, so don’t need to make much of this enzyme
proteolytic
- secreted as proenzymes
- activated within lumen of stomach or SI
proenzymes
- zymogens
- secreted from cells but have to interact with something to activate it
how do zymogens work
part of protein blocks active site of enzyme, which cleaves off the peptide and activates enzyme
cavital and intestinal peptidases
cavital
- breaking peptides
- gastric pepsin
- pancreatic trypsin, chymotrypsin, carboxypeptidase
intestinal
- aminopeptidase
- dipeptidase
- tripeptidase
what is the inactive form of enzyme
zymogen or proenzyme
why is regulation need for turning off and on enzymes
so too much or too little is used
pepsin
- relatively inactive except at pH below 3.5
- relatively inactive in young ruminants
- attacks peptide bonds involving aromatic amino acid
why is it important that Pepsin in inactive in young ruminants
- colostrum
- gut is open
- short window of time where passage of antibodies can occur
Rennin
- enzyme that breaks down proteins
- produced by chief cells
- coagulates milk
- control flow of curd from abomasum to small intestine
- most active in neonate and replaced by pepsin
what is the main role of rennin
coagulate milk
- makes it a semi sold so passage rate is slower
- gives body more time for digestion
trypsin
acts on peptide linkages involving carboxyl group
chymotrypsin
most active on phenylalanine, tyrosine, and tryptophan
trypsin + chymotrypsin=additive
- work on series of different bonds
- hydrolyze interior bonds
- endopeptidases
those that act on terminal amino acids
exopeptidases
bile
- role in digestion
- contains salts that are recirculated
- provides alkaline pH in SI
- prepares fats for absorption
- serves as route for excretion of metallic elements, inactivated hormones, etc.
what are bile pigments responsible for
color of bile and urine and feces
lipolytic
- pancreatic lipase (hydrolyzes bonds between 1 and 3 fatty acid)
- intestinal lipase
- aided by bile
triglyceride
3 fatty acids that attach to glycerol backbone
esterase
- break Esther bonds
- phospholipase
- cholesterol esterase
pancreatic lipase
- hydrolyzes fatty acids in 1 and 3 position of triglycerides
- produce free fatty acids and 2-monoglycerides
effect of age on carbohydrase activity in swine
birth to 3 weeks
- lactase increases not induced
- amylase, maltase, sucrase low and not inducible
3 to 5 weeks to adult
- lactase may or may not decrease
- amylase, maltase, sucrase induced and increased
not induced
pre-programmed by body to do what is supposed to do
- stimulus not needed
inducible
stimulus needed and body will respond and produce enzyme
age affect in ruminants
0 to 3 weeks
- lactase high
- other enzymes low
- inducible
3 to 8 weeks
- rumen and microbes starting to develop
- lactase induced
- amylase and maltase induced
- no sucrase
8 weeks (functional rumen)
- lactase inducible
- amylase and maltase activity limited
- no sucrase
why are amylase, maltase, and sucrase low or not present in adult ruminants
microbes are taking care of staches and sugars first, so body doesn’t need to spend energy on digesting or creating anatomy for these
