Physiology 2 - For Exam 4

Front 1

Which "part" of the pancreas is associated with digestive secretions?

Back 1

Exocrine pancreas

Front 2

what are the two major functions of the exocrine pancreas?

Back 2

1. contribute to luminal enzymatic digestion of food nutrients
2. buffer digesta entering the SI

Front 3

what are the two histological divisions of the exocrine pancreas and what is the function of each unit?

Back 3

1. acinar cells - produce, secrete, and store digestive proenzymes. Proenzyme rich and bicarb poor

2. ducts - produce and secrete bicarbonate. Bicarb rich and proenzyme poor

Front 4

what is the general name for the inert proteins secreted by the exocrine pancreas, where are they secreted, and what happens to them when they are secreted?

Back 4

Proenzymes are produced and secreted by the acinar cells of the exocrine pancreas, secreted into the small intestine, and cleaved into active enzymes by trypsin.

Front 5

what is another name for a proenzyme?

Back 5

zymogen

Front 6

how are nucleic acids digested?

Back 6

by DNAses and RNAses, which are secreted as proenzymes by the exocrine pancreas.

Front 7

name the zymogen form for the following enzymes:

1. trypsin
2. chymotrypsin
3. elastase
4. carboxypeptidase A
5. DNAse

Back 7

1. trypsinogen
2. chymotrypsinogen
3. proelastase
4. procarboxypeptidase A
5. proDNAse

Front 8

true or false: any specific enzyme secreted by the pancreas can digest a variety of different chemical bond types, thus making them very powerful in digestion.

Back 8

false. Each specific enzyme cleaves a specific bond type.

Front 9

what are the four major lipid digesting enzymes produced by the exocrine pancreas?

Back 9

1. pancreatic lipase
2. pancreatic co-lipase
3. cholestrol esterase
4. phoshpholipase

Front 10

which pancreatic digestive enzymes are secreted in their active forms?

Back 10

only pancreatic amylase

Front 11

how is acid-base balance in the lumen and blood accompished by the stomach and pancreas?

Back 11

with carbonic anhydrase ("CA"), CO2, and water:

- the gastric parietal cells secrete H+ into the gastric lumen and bicarb into the blood

- the pancreatic ducts secrete bicarb from the blood into the duodenal lumen, producing carbonic acid, which is catalyzed back to water and CO2 by CA.

Front 12

***true or false: endopeptidase cleaves trypsinogen to trypsin in the duodenum?

Back 12

false. ENTEROpeptidase does this.

Front 13

what two enzymes cleave trypsinogen to trypsin?

Back 13

1. enteropeptidase
2. trypsin

Front 14

what is the function of trypsin?

Back 14

to cleave zymogens secreted into the intestinal lumen to active enzymes. Also, it cleaves trypsinogen to trypsin.

Front 15

what is the most common pathogenesis of pancreatitis?

Back 15

the pancreas is overstimulated and produces many enzymes due to loss of normal pancreatic inhibition. In this case, trypsinogen will be cleaved to trypsin in the pancreas, activating the pancreatic enzymes inside the pancreas. The result is the pancreas digesting itself.

Front 16

what are the three general physiologic controls of exocrine pancreatic secretion

Back 16

1. vagal stimulation
2. intrinsic GI nervous stimulation
3. endocrine stimulation from the small intestine

Front 17

how does vagal stimulation control pancreatic secretion, what types of neurons are they, and what factors activate them?

Back 17

secretory branches of the vagus nerve stimulate pancreatic secretion. They are affected by sight/smell of food (cephalic phase) and gastric distension (gastric phase).

Front 18

what two major functions does the intrinsic GI nervous system provide to control exocrine pancreas secretion?

Back 18

1. stimulates pancreas acinar cells (zymogens)
2. reinforces cephalic and gastric phases

Front 19

What effect does neural stimulation have on bicarb secretion by the exocrine pancreas?

Back 19

Little to none

Front 20

what are the two hormones that control exocrine pancreas secretion and where are they produced?

Back 20

secretin and cholecystokinin (CCK) produced by the small inestine - especially the duodenum.

Front 21

where is secretin produced and released? What stimulates its secretion? What are its effects?

Back 21

- produced and released by the first few cm of the duodenum in response to gastric acid
- stimulates the ducts of the exocrine pancreas to produce copious amounts of bicarb
- weak stimulator of bile and pancreatic enzymes

Front 22

where is CCK produced and released? What stimulates its secretion? What are its effects?

Back 22

(cholecystokinin)
- produced by most of the duodenum in response to the presence of digesta in the lumen
- stimulates the acini of the exocrine pancreas to secrete enzyme-rich fluid
- is a weak stimulator of bicarb secretion

Front 23

how do secretion and CCK affect each other?

Back 23

they augment each others' release

Front 24

in non-ruminants, where is the primary site of digestion? Where is the primary site of absorption?

Back 24

Both in the small intestine

Front 25

what are the major functions of the small intestine in ruminants?

Back 25

- fat digestion
- required for protein digestion and absorption
- water and electrolyte reabsorption

Front 26

what are the two anatomical structures of the small intestine most responsible for increasing its surface area?

Back 26

microvilli and glycocalyx

Front 27

what four anatomical features allow very efficient digestion and absorption by the small intestine?

Back 27

1. high surface area
2. "loose" tight junctions
3. high surface area basolateral membranes
4. capillaries and lacteals very close to the lateral spaces

Front 28

what inhibits CCK secretion?

Back 28

loss of substrates from the late jejunum

Front 29

what inhibits secretin secretion?

Back 29

negative feedback (e.g. pH)

Front 30

what are the two main "aims" of the digestive phase of small intestinal motility?

Back 30

1. promote digestion and absorption

2. move digesta aborally at an appropriate rate

Front 31

what is the predominate mechanism that the small intestine uses to mix digesta with enzymes?

Back 31

segmentation

Front 32

by what two means of controlling motility does the small intestine allow adequate time for digestion and absorption?

Back 32

1. the duodenal pacemaker
2. retentive form of gut motility to allow time for absorption

Front 33

what are the two mechanisms by which the small intestine moves digesta at an appropriate rate?

Back 33

1. "regular" peristalsis, where digesta progresses only short distances.
2. peristaltic rush, where particularly strong waves respond to obstruction (much like secondary peristalsis of the esophagus)

Front 34

what is the interdigestive phase of small intestine motility?

Back 34

the "housekeeper" modified peristalsis, that cleans out larger particles

Front 35

what is the function of the muscularis mucoase in small intestine motility?

Back 35

"waves" the intestinal villi in the "soup" of digesta

Front 36

characterize the connection of the ileum to the large intestine

Back 36

it is an ileocolic or ileocecal spincter that is held tonically closed, and must relax to allow digesta to enter the large intestine

Front 37

what are the two neural controls and function of those controls of small intestinal motility?

Back 37

1. intrinsic: myentric plexuses - intraintestinal communication
2. extrinsic: ANS - "influences" the myenteric plexuses

Front 38

how does CCK influence small intestinal motility? Secretin?

Back 38

They both increase motility. Remember that these two enzymes work in concert.

Front 39

obstruction of the intestines caused by failure of peristalsis

Back 39

ileus

Front 40

what are the two types of diarrhea that occur in the small intestine?

Back 40

hypermotile and hypomotile

Front 41

what are the four general phases of digestion and absorption in the small intestine?

Back 41

1. luminal phase
2. mucosal ("membranous") phase
3. intracellular phase
4. absorption

Front 42

what are the main chemical components in the luminal phase of digestion in the small intestine?

Back 42

pancreatic and/or gastric enzymes

Front 43

why is the luminal phase of digestion in the small intestine generally not sufficient to allow absorption of nutrients?

Back 43

because the particles are still too large. Only monomers, dimers, and trimers can be absorbed.

Front 44

in the mucosal phase, what organ produces the enzymes used for digestion, and where are the enzymes located?

Back 44

they are produced by the small intestine only and bound to the glycocalyx.

Front 45

what is the maximum size of digesta that can be absorbed by the small intestine?

Back 45

trimers

Front 46

by what two routes can digesta pass from the small intestinal lumen to the basolateral space/interstitium?

Back 46

1. intracellularly by secondary active transport
2. paracellularly through "leaky" tight junctions

Front 47

describe the intracellular phase of digestion in the small intestine.

Back 47

- it occurs ONLY in the small intestine
- only dipeptides and tripeptides
- they are converted to amino acid monomers

Front 48

where do nutrients pass in small intestinal absorption after they enter the interstitium?

Back 48

blood and lymph

Front 49

what type of carbohydrate is indigestible by all domestic mammals?

Back 49

lignin

Front 50

where does most digestion of soluble carbohydrates occur in non-ruminants?

Back 50

small intestine

Front 51

what are the four major sites of carbohydrate digestion in non-ruminants and what enzymes are used?

Back 51

1. oral lumen - salivary amylase
2. gastric fundus - salivary amylase
3. enteric lumen (duodenum and jejunum) - pancreatic amylase
4. mucosal (jejunum) - small intestinal enzymes on the glycocalyx

Front 52

where does luminal digestion of CHOs by pancreatic amylase take place in the non-ruminant?

Back 52

duodenum and jejunum

Front 53

which part of the small intestine exhibits the greatest mucosal digestion of CHOs in the non-ruminant?

Back 53

jejunum

Front 54

generally, how are CHOs moved intracellularly from the lumen of the small intestine?

Back 54

by secondary active co-transport with sodium. Note that only monosaccharides can enter the enterocytes and be absorbed.

Front 55

how do sugars move from the basolateral membrane of the luminal cells to the basal interstitium of the small intestine?

Back 55

facilitated diffusion

Front 56

what are major sources of protein absorbed in the small intestine?

Back 56

- dietary
- sloughed-off mucosal cells
- digestive enzymes
- (ruminant) microbial protein

Front 57

what are the products of oral luminal digestion of protein?

Back 57

none. Protein digestion does not occur in the oral lumen.

Front 58

what are the products of gastric luminal digestion of protein in the non-ruminant?

Back 58

proteoses

Front 59

In the non-ruminant, what chemicals are used in the gastric luminal phase of protein digestion?

Back 59

gastric acid and gastric enzymes

Front 60

In the non-ruminant, where does the majority of protein digestion occur?

Back 60

small intestinal lumen is the largest
small intestine mucosa is also very important

Front 61

what is the maximum size protein that can enter an enterocyte in the non-ruminant?

Back 61

tripeptide

Front 62

where are pepsins used, what do they digest, and what type of enzyme are they in the non-ruminant?

Back 62

pepsins are protein-digesting endopeptidases used in gastric luminal digestion.

Front 63

what are the two main types of pancreatic proteases and how do they differ in the non-ruminant?

Back 63

- endopeptidases: cleave proteins inside of the chain
- exopeptidases: cleave individual amino acids from the carboxyl ends of proteins

Front 64

what proteases are present on the non-ruminant small intestinal mucosa and what do they do?

Back 64

- aminopeptidases - cleave individual amino acids from the N-position; produce mono-, di-, and tripeptides
- dipeptidases - produce dipeptides

Front 65

where does the majority of dipeptide and tripeptide digestion occur in the non-ruminant?

Back 65

In the small intestine enterocytes.

Front 66

by what mechanisms are amino acids transported from the enterocyte to the blood in the non-ruminant?

Back 66

facilitated diffusion and Na-dependent co-transport

Front 67

by what mechanism are intact proteins absorbed by neonates?

Back 67

pinocytosis

Front 68

what is the term used for when a neonate can no longer absorb whole proteins?

Back 68

gut closure

Front 69

what three organs are primarily responsible for digestion of dietary fat?

Back 69

stomach, small intestine, liver

Front 70

what enzyme is used for the digestion of triglycerides in the gastric lumen?

Back 70

none

Front 71

where does enzymatic fat digestion occur in the non-ruminant?

Back 71

small intestine only

Front 72

what is the 7-step process of triglyceride digestion and absorption in the small intestine?

Back 72

1. emulsification by bile
2. enzymatic hydrolysis to fatty acids
3. micelle formation
4. uptake by the enterocyte
5. conversion back to triglyceride
6. formation of chylomicrons
7. absorption into the central lacteal

Front 73

which energy-yielding nutrient has no mucosal phase of digestion?

Back 73

lipids

Front 74

true or false: emulsification of fat by bile is a form of mechanical digestion?

Back 74

true

Front 75

what are the main enzymes that digest triglycerides?

Back 75

1. pancreatic lipase
2. pancreatic co-lipase

Front 76

what is the function of pancreatic co-lipase?

Back 76

"sweeps" bile out of the way so that pancreatic lipase, which can not enter a fat globule, can work.

Front 77

what are the products of the complete digestion of a triglyceride by pancreatic lipase?

Back 77

2 FFAs and a monoglyceride

Front 78

what are the main components of a micelle in the small intestine?

Back 78

- bile
- cholesterol
- free fatty acids
- monoglycerides
- vitamin A

Front 79

where, in the intercellular phase of fat digestion, are fats assembled into triglycerides and then chylomicrons

Back 79

SER

Front 80

how are chylomicrons transported from the SER to the blood?

Back 80

1. Golgi puts it into a vesicle
2. vesicle fuses with the basolateral membrane
3. chlyomicron enters the central lacteal and into the lymphatic system
4. enters the blood via the thoracic duct

Front 81

what is lipemia?

Back 81

chylomicrons in the plasma following a fatty meal

Front 82

how is bile recovered/reused in the small intestine?

Back 82

- about half is PASSIVELY absorbed in the jejunum
- the other half is reused
- if it enters the ileum, it is ACTIVELY transported

Front 83

why is the ileum important in fat digestion?

Back 83

because it recovers almost all of the bile that passes into it

Front 84

why is poop brown?

Back 84

bile

Front 85

what major function does the large intestine perform in all species?

Back 85

electrolyte and water absorption

Front 86

how does digestion occur in the large intestine, if any?

Back 86

fermentation

Front 87

what is the most significant immune function in the large intestine?

Back 87

plasma cells in the lamina propria produce IgA

Front 88

what part of the large intestine is not involved in digestion or absorption?

Back 88

rectum

Front 89

what are the major electrolytes absorbed by the large intestine and by what mechanism does this occur?

Back 89

- Na (and Cl) via Na-K-ATPase
- K via H-K-ATPase

Front 90

how is digesta transported from the ascending colon into the cecum?

Back 90

retroperistalsis

Front 91

how is digesta retained in the cecum for water absorption and digestion?

Back 91

stationary haustral contractions

Front 92

the movement of large volumes of material from the cecum to the large intestine

Back 92

mass movement

Front 93

how does motility in the large intestine differ from the cecum?

Back 93

the large intestine does not use retroperistalsis (except in the delivery of digesta to the cecum in non-equids)

Front 94

true or false: defecation can be defined as a sustained colonic contraction

Back 94

false

Front 95

how is defecation initiated?

Back 95

defecation reflex, which is activated by the distention of the descending colon and/or rectum

Front 96

what components of the ANS are involved in defecation?

Back 96

afferent and efferent neurons are both parasympathetic and arise from the pelvic plexuses and pelvic nerves.

Front 97

what four major groups of muscles are involved in defecation? (yes, I know that this is a lovely subject)

Back 97

1. mass movement contractions of the colon
2. contraction of the longitudinal rectal muscles
3. anal sphincters
4. skeletal muscles such as the abs and diaphragm (squeeze!)

Front 98

the two anal sphincters:
- name
- muscle type
- innervation
- major function

Back 98

1. internal anal sphincter; smooth muscle; pelvic nerve; kept tonically contracted for continence

2. external anal sphincter; skeletal muscle; pudendal nerve; "oh no, next rest stop!" and closure of the anus after defecation

Front 99

what is the rectosphincteric reflex?

Back 99

as fecal mass enters the rectum, defecation ensues.

Front 100

in the act of counteracting the urge to defecate, what must be counteracted and how is this accomplished?

Back 100

the rectosphincteric reflex "overrided" by contraction of the external anal sphincter and stretch relaxation of the rectum

Front 101

why do animals fart?

Back 101

1. swallowing of air
2. intraluminal flora

Front 102

what nutrients are digested most by microbes?

Back 102

CHOs and protein (fat is only partially digested by microbes)

Front 103

what major vitamins are synthesized by fermenting microbes?

Back 103

B Vitamins

Front 104

what types of microbes are involved in fermentation and where are they located?

Back 104

bacteria - foregut and hindgut
protozoa - foregut and hindgut
fungi - mainly foregut

Front 105

***where in horses and ruminants is digesta stored for fermentation?

Back 105

ruminants - rumen
horses - ***ASCENDING*** colon and cecum

Front 106

what five major physiological conditions are maintained by the fermenting animal to keep its microbial flora happy?

Back 106

1. anerobic conditions (required for fermentation)
2. temperature
3. pH (buffers)
4. osmolarity near 300 mOsm
5. removal of microbial waste products

Front 107

how are microbial waste products handled by the animal (foregut and hindgut fermenters, specifically)?

Back 107

they are absorbed as nutrients

Front 108

why do horses require higher protein in their diets than ruminants

Back 108

because ruminants digest microbes as their protein source. Horses cannot use microbial protein because they are hindgut fermenters

Front 109

what are the major gases produced by microbial fermentation?

Back 109

CO2 and CH4

Front 110

how does the foregut and small intestine aid in fermentation in the hindgut in horses?

Back 110

partial digestion: acids, enzymes, soaking, and motility

Front 111

compare the digestion of sugars and starches by the small intestine of horses versus carnivores.

Back 111

not as efficient. Some of the sugar and starch is fermented.

Front 112

if the horse digests its protein in the small intestine, how do the microbes in its ascending colon and cecum get the protein that they need?

Back 112

From urea, secreted into the colonic lumen from the blood, and converted to ammonia by microbial urease. They use this ammonia to make proteins and amino acids for themselves.

Front 113

although amino acid absorption in the hindgut of the horse is minimal compared to its diet, why is it important?

Back 113

microbes synthesize essential amino acids

Front 114

what are the two flow-reducing anatomical features in the equine ascending colon?

Back 114

1. right colic flexure - major effect
2. pelvic flexure
(note that sternal and diaphragmatic flexures are much more minor compared to the above two)

Front 115

what are the four functional regions of the intestines of the horse as related to digestion?

Back 115

1. cecum
2. ventral colons
3. dorsal colons
4. descending colon

Front 116

in the horse, what transfers digesta from the small to the large intestine?

Back 116

ileocecal orifice

Front 117

how does delivery of digesta to the cecum differ in the horse from other animals?

Back 117

it passes directly into the cecum via the ileocecal orifice. Thus, no retroperistalsis from the colon to cecum is present.

Front 118

what is the main job of the horse cecum and how is this accomplished?

Back 118

to mix the digesta to start fermentation. This is done by:
- frequent segmentation from hausta to haustra
- occasionally, a retroperistaltic mass movement from cecal apex to base, which delivers digesta to the RVC via the ceocolic orifice

Front 119

what are the three major types of colonic motility in the ventral and dorsal colons of the horse?

Back 119

much the same in the ventral colons versus the dorsal colons
1. haustral segmentation
2. propulsive peristalsis
3. retentive peristalsis

Front 120

what is the function of propulsive peristalsis in the horse's ventral colons?

Back 120

to move digesta along the ventral colons and to the dorsal colons

Front 121

in the horse's ventral colons, where is the pacemaker for retentive peristalsis, and where is retentive peristalsis best-developed?

Back 121

- the pacemaker and particle sorting pyloris-like sphincter is at the pelvic flexure
- the LVC is best developed for retentive peristalsis

Front 122

in the horse's dorsal colons, where does retentive peristalsis originate, and where is retentive peristalsis best-developed?

Back 122

originates at the right colic flexure
best developed in the RDC

Front 123

why is there so much water movement in the colon of the horse?

Back 123

to absorb VFAs and to maintain osmolarity

Front 124

how is the large intestine buffered in the horse?

Back 124

bicarb and phosphate secreted by the ileum and by the crypts of the mid-to later ascending colon

Front 125

what are the two functions of bicarb and phosphate in the horse's ascending colon?

Back 125

1. buffer the pH
2. maintain osmolarity

Front 126

how and why are fecal balls produced by the horse?

Back 126

by segmentation in the descending colon to reabsorb water and electrolytes

Front 127

what are the three time periods of natural bovine gastric development?

Back 127

1. "nonruminant"
2. transitional period
3. "adult"

Front 128

what three major stimuli cause reflexive closure of the gastric groove in the juvenile ruminant?

Back 128

1. cephalic (anticipation of suckling)
2. salts in the pharynx (chemoreceptors)
3. the activity of suckling

Front 129

what stimulates the gastric groove to close in adult ruminants?

Back 129

ADH (thirsty!)

Front 130

what stimulates papillae to develop in the rumen?

Back 130

VFAs

Front 131

what are the four major functions of the reticulorumen?

Back 131

1. promote fermentation by mixing and sorting digesta
2. prepare digesta for remastication and reinsalivation (reticulum)
3. absorb VFAs
4. eructation of gases released form fermentation

Front 132

how does digesta move to the omasum and what is the basic function of the omasum?

Back 132

- sucks the digesta into itself
- "treats" digesta for passage into the abomasum

Front 133

what are the three major places, in the rumen, where ruminal bacteria reside, and what do they do?

Back 133

1. in the fluid, free-floating to ferment dissolved nutrients
2. on food particles, mostly cellulose
3. on the epithelium to digest sloughed-off epithelial cells.

Front 134

how do the bacteria associated with the ruminal epithelium differ from that of the other bacteria in the rumen?

Back 134

they use O2 from the blood of the ruminant

Front 135

how do ruminal fungi digest nutrients?

Back 135

they ferment plant fiber and physically digest them by breaking them apart with their hyphae

Front 136

what is the product of triglyceride fermentation in the rumen?

Back 136

FFAs and glycerol

Front 137

true or false: most ingested protein escapes fermentation by the rumen and is instead digested by the abomasum and small intestine?

Back 137

false. SOME dietary protein escapes the rumen. Most is fermented.

Front 138

what are the four major sources of urea in the ruminant?

Back 138

1. diffusion into rumen from the blood
2. ammonia given off by bateria is converted to urea by the liver and put back into rumen
3. saliva
4. feed additive

Front 139

how does water enter the rumen?

Back 139

drinking only. Little to no luminal secretion.

Front 140

how does saliva vary with diet in the ruminant?

Back 140

the more roughage, the more saliva produced

Front 141

how is the rumen pH buffered?

Back 141

by buffers from the saliva

Front 142

what are the two basic functions of water in the reticulorumen?

Back 142

1. assists in sorting and movement of variously processed digesta
2. delivers microbes and digesta to omasum, abomasum

Front 143

what are the six basic zones of the reticulorumen and where are they located?

Back 143

1. gas zone - upper part od dorsal sac
2. "bubbly" solid zone ("rumen mat") - floats on top of the fluid zones
3. ejection zone - near the cardia for eructation and regurgitation
4. slurry zone
5. liquid "non-bubbly zone" - finished fermenting
6. zone of potential escape - ventral parts of the reticulum and cranial sac; regurgitation or passage to omasum

Front 144

by what three ways is ruminal motility controlled?

Back 144

1. endocrine (minor)
2. intrinsic nervous system - very complex
3. CNS - vagus nerve

Front 145

what will happen to ruminal motility if the vagus nerve is cut?

Back 145

- the rumen will have uncoordinated contractions: poor mixing of digesta
- stretch receptors (and others) will not reach the brain, so the animal will keep eating
- the ruminant will eventually die from bloat

Front 146

what five physiological conditions of the rumen are monitored by the vagal nucleus?

Back 146

1. ruminal distention
2. consistency of the digesta
3. pH
4. concentration of VFAs
5. osmolarity (minor)

Front 147

how does ruminal distention affect rumen motility

Back 147

slows it; bloat stops it.

Front 148

how does the fluidity of digesta affect rumen motility?

Back 148

more fluid - slower
more solid - faster and stronger

Front 149

how does pH affect rumen motility?

Back 149

low (<5) slows so VFAs can be absorbed
high (>7) increases to promote fermentation

Front 150

how does ruminal VFA concentration affect rumen motility?

Back 150

high VFA concentrations slows rumen motility

Front 151

how does the strength of reticulum contraction affect digestion?

Back 151

- moderate sorts digesta
- virorous sends fluid to omasum and coarse particles back to rumen

Front 152

what are the four main waves of contraction of the rumen and their functions?

Back 152

1. caudally-directed peristaltic wave of the dorsal ruminal sac: mixes and sorts
2. caudally-directed peristaltic wave of the ventral ruminal sac: mixes and sorts
3. cranially-directed peristalic wave of dorsal sac: mixes, sorts, washes digesta into reticulum
4. cranially-directed peristalic wave of ventral sac: mixes, sorts, washes digesta into reticulum

Front 153

what is the purpose of and process of secondary ruminal contraction?

Back 153

- eructation

1. cranially directed wave begins at caudal dorsal blind sac, moves over dorsal sac to cardia
2. cranial pillar elevates and cranial sac relaxes as wave approaches to drop liquid level.
3. lower esophageal sphincter relaxes and gas escapes

Front 154

what is the process of regurgitation in the ruminant?

Back 154

1. rumen contracts, delivering bolus to the lower esophageal sphincter
2. lower esophageal sphincter relaxes and bolus enters esophagus
3. reverse peristalsis carries bolus to mouth
4. fluid reswallowed; bolus is remasitcated, resalivated, and swallowed

Front 155

what is secreted into the ruminant saliva to buffer the rumen?

Back 155

phosphate and bicarb

Front 156

where are most VFAs absorbed by the ruminant, and what cell-type is involved in the absorption?

Back 156

stratified squamous epithelium of the ruminal papillae

Front 157

what is the most important enzyme secreted in the abomasum to digest bacterial cell walls?

Back 157

lysozyme