Lecture 5 Part 1

Question 1

what are the roles of GIT secretions

Answer 1

1. lubricate and protect through saliva and mucus
2. alter pH
3. things that do digestion, enzymes
4. things that assist with digestion, bile

Question 2

why does the GIT need to be protected through saliva and mucus

Answer 2

• so don’t tear holes in GIT
• easier swallowing
• protect pH so no ulcers

Question 3

what are some examples of enzymes that alter pH

Answer 3

• HCl in stomach to create acidic
• bile salts in SI to make basic

Question 4

how does bile assist with digestion

Answer 4

emulsify fats so they are more easily digested

Question 5

what is special about the digestive enzymes

Answer 5

• very specific in target substrate
• very specific in where in substrate they attach and react

Question 6

what is an enzyme

Answer 6

• substance produced by living organisms that acts as catalyst to bring about specific reaction
• breaks bonds
• proteins

Question 7

what are the ways to describe an enzyme

Answer 7

• source (ex: salivary amylase)
• substrate
• end product

Question 8

where is the location of enzymes and microbes in ruminants

Answer 8

• microbial fermentation in rumen
• followed by digestive enzyme action in small intestine
• ruminants live off what microbes produce
• collective work of enzymes

Question 9

location of enzymes and microbes in non-ruminant

Answer 9

• digestive enzymes attack feed prior to microbial fermentation
• enzymes working before fermentation

Question 10

benefits of microbes in ruminants

Answer 10

• microbial fermentation allows cattle to thrive on fibrous feed
• high quality dietary protein & starch degraded
• low quality dietary protein improved by microbes

Question 11

where in the body are the most nutritionally significant enzymes produced

Answer 11

pancreas and walls of small intestine

Question 12

why in some species are the salivary enzymes present but not important

Answer 12

because the enzymes are rapidly denatured in stomach

Question 13

what does cavital mean

Answer 13

secreted
- produced in one area and then to work in another

Question 14

what are some cavital enzymes

Answer 14

• salivary
• gastric
• pancreatic

Question 15

what does intestinal mean

Answer 15

• not secreted
• in intestine
• imbedded within a cell or brushed border

Question 16

what are some intestinal enzymes

Answer 16

• membrane (brush border)
• intracellular (mucosal cells)

Question 17

what does low pH in stomach do to enzymes

Answer 17

denature

Question 18

what are the types of enzymes

Answer 18

• carbohydrase
• proteolytic
• lipolytic

Question 19

carbohydrase

Answer 19

• breaking carbs
• most generic

Question 20

what are the two kinds of carbohydrase

Answer 20

• amylolytic: digest starch and simple sugars
• cellulytic: digest cellulose and other nonstarch polysaccharides

Question 21

polysaccharides

Answer 21

breaks down cellulose

Question 22

amylolytic

Answer 22

• source= salivary/pancreatic
• cleaves the alpha 1, 4 glycosidic bonds
• cavital glycosidase

Question 23

glycosidase

Answer 23

enzyme that breaks bonds between 2 carbons

Question 24

what does amylase digest

Answer 24

amylose into glucose

Question 25

lactase digests

Answer 25

lactose into glucose and galactose

Question 26

sucrase digests

Answer 26

sucrose into glucose and fructose

Question 27

mannase digests

Answer 27

mannose into glucose

Question 28

what is intestinal glycosidases

Answer 28

- part of brush border - not secreted - source= imbedded in cell

Question 29

what is special for cellultyic enzymes

Answer 29

- only microbes produce this enzyme

Question 30

what do mammals need to assist with to digest structural polysaccharides

Answer 30

microbes

Question 31

why is sucrase not found in ruminants

Answer 31

microbes break sugar down first so no sugars reach intestine - must take into consideration amount included in milk replacer

Question 32

why is pancreatic amylase production low in ruminants

Answer 32

microbes break starch down first so not starch will reach intestine, so don't need to make much of this enzyme

Question 33

proteolytic

Answer 33

- secreted as proenzymes - activated within lumen of stomach or SI

Question 34

proenzymes

Answer 34

- zymogens - secreted from cells but have to interact with something to activate it

Question 35

how do zymogens work

Answer 35

part of protein blocks active site of enzyme, which cleaves off the peptide and activates enzyme

Question 36

cavital and intestinal peptidases

Answer 36

cavital - breaking peptides - gastric pepsin - pancreatic trypsin, chymotrypsin, carboxypeptidase intestinal - aminopeptidase - dipeptidase - tripeptidase

Question 37

what is the inactive form of enzyme

Answer 37

zymogen or proenzyme

Question 38

why is regulation need for turning off and on enzymes

Answer 38

so too much or too little is used

Question 39

pepsin

Answer 39

- relatively inactive except at pH below 3.5 - relatively inactive in young ruminants - attacks peptide bonds involving aromatic amino acid

Question 40

why is it important that Pepsin in inactive in young ruminants

Answer 40

- colostrum - gut is open - short window of time where passage of antibodies can occur

Question 41

Rennin

Answer 41

- 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

Question 42

what is the main role of rennin

Answer 42

coagulate milk - makes it a semi sold so passage rate is slower - gives body more time for digestion

Question 43

trypsin

Answer 43

acts on peptide linkages involving carboxyl group

Question 44

chymotrypsin

Answer 44

most active on phenylalanine, tyrosine, and tryptophan

Question 45

trypsin + chymotrypsin=additive

Answer 45

- work on series of different bonds - hydrolyze interior bonds - endopeptidases

Question 46

those that act on terminal amino acids

Answer 46

exopeptidases

Question 47

bile

Answer 47

- 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.

Question 48

what are bile pigments responsible for

Answer 48

color of bile and urine and feces

Question 49

lipolytic

Answer 49

- pancreatic lipase (hydrolyzes bonds between 1 and 3 fatty acid) - intestinal lipase - aided by bile

Question 50

triglyceride

Answer 50

3 fatty acids that attach to glycerol backbone

Question 51

esterase

Answer 51

- break Esther bonds - phospholipase - cholesterol esterase

Question 52

pancreatic lipase

Answer 52

- hydrolyzes fatty acids in 1 and 3 position of triglycerides - produce free fatty acids and 2-monoglycerides

Question 53

effect of age on carbohydrase activity in swine

Answer 53

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

Question 54

not induced

Answer 54

pre-programmed by body to do what is supposed to do - stimulus not needed

Question 55

inducible

Answer 55

stimulus needed and body will respond and produce enzyme

Question 56

age affect in ruminants

Answer 56

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

Question 57

why are amylase, maltase, and sucrase low or not present in adult ruminants

Answer 57

microbes are taking care of staches and sugars first, so body doesn't need to spend energy on digesting or creating anatomy for these