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RUSVM Physio II *TWO* > GI 4 > Flashcards

GI 4 Flashcards

1
Q

What are the functions of the omasum?

A

Concentrate ingesta (absorb water)

VFA (SCFA) absorption - diffusion

Na and Cl absorption (cotransporter)

HCO3- reabsorbed (antiport with Cl-)

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2
Q

The forestomach of the ruminant is lined with _____________________ epithelium

A

Stratified squamous epithelium

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3
Q

Microbes used _______ and __________ to synthesize amino acids

A

Ammonia (NH3) and volatile fatty acids (VFA)

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4
Q

What are the two main mechanisms that VFA are absorbed in the rumen

A

Ionized- require carrier (HCO3-/Ac-antiport)

Non-ionized - diffuse through apical membrane

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5
Q

What is rumen acidosis ?

A

Fast-fermentable carbohydrates (starch rich) can lead to increased VFA production –> acids decrease the pH of rumen

VFA have pka of 4.8 => more acid will be in HAc form than Ac-
HAc can diffuse direct through membrane
Less Ac- antiport with HCO3- (less HCO3- to rumen => pH increases)

Acidic pH -> proliferation of lactate-producing bacteria –> lactic acid -> more acidic

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6
Q

What are the layers of the ruminal contents?

A

Gas
Fiber mat
Intermediate zone
Liquid zone

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7
Q

the ________________center is located in the medulla and receives afferent fibers from mechanoreceptor in the dorsal sac where gas accumulates

A

Eructation

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8
Q

Horses and rabbits are ___________ fermenters

A

Hindgut

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9
Q

All the glucose available to ruminants is formed by ________________

A

Gluconeogenesis

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10
Q

Proprionate is absorbed from the portal blood supply by the _________

A

Liver

Never enters systemic circulation

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11
Q

What invagination of the wall of the reticulum spans from the cardia to the recticulo-omasal orfice; it diverts milk away from developing rumen, directly into abomasum

A

Recticular groove (esophageal groove)

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12
Q

How is sodium absorbed in the rumen?

A

Na+ channel- Apical (electrochemical gradient)
Na/N exchanger -apical

Na/K ATPase- basolaterally

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13
Q

What is the main function of primary contractions of the rumen?

A

Reduce particle size

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14
Q

What is the fate of short chain peptides in the microbial cell?

A

Hydrolyzed to amino acids

  • > synthesis of microbes protein
  • > metabolized to VFA and ammonia
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15
Q

Urea can be recycled to the rumen to produce proteins for the host, what are the two sources of urea?

A

Deamination of endogenous amino acids -> ammonia
Nitrogen absorbed as ammonia from rumen

Liver turns ammonia back to urea which is returned back to the rumen

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16
Q

How are fats hydrolyzed in the ruminant?

A

Microbial lipase

Anaerovibrio lipolytica -> triglycerides

Buyrivibrio fibrisovlens -> phospholipid and glycolpids

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17
Q

What can occur in cattle when the eructation mechanism fails ?

A

Tympanism or bloating

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18
Q

How is magnesium absorbed in the rumen?

A

Mg2+ channel

Affected by K+ concentrations

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19
Q

How is chloride reabsorbed into the rumen?

A

Cl-/HCO3- exchanger -apical

Basolateral channel

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20
Q

What are the primary volatile fatty acids

A 
Acetic acid (acetate)
Propionic acid (propionate) 
Butyric acid (butyrate)
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21
Q

Most dietary protein undergoes fermentation in the microbes within the rumen. How does the animal meet its protein needs?

A

Microbial proteins

Microbes are washed out of the rumen with rumen fluids to the abomasum and small intestine -> digestion of microbes

Other sources
Ammonia, nitrates, and urea synthesized to protein within rumen

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22
Q

What minor component of diary feeds is a major component of fat supplements

A

Free fatty acids

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23
Q

What enzymes do microorganisms produce for lipid digestion

A

Lipase and phospholipids

Usually rare in plants, but fats are added to diets to increase energy density

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24
Q

What are the steps of the mixing/primary contractions of the rumen?

A

Bolus enter rumen to cardia

Biphasic contraction of rumen - weak followed by forceful to push larger particles to dorsal sac

Caudal-moving contraction of dorsal sac pushes ingesta farther back

Cainial-moving contraction of dorsal sac- > mix ingesta and start bacteria fermentation

Smaller particles decant to ventral sac separates big and small material

Ventral sac contraction- smaller particles to over crainial pillar to the crainial sac

Cranial sac contracts -further separates to small and large particles

Recticulum contract, recticulum-omasal orfice relax and small particle go omasum

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25
What minor components of most feeds forms cell membranes of animal cells and the surface of milk fat globules
Phospholipids
26
How is potassium absorbed in the rumen?
Apical and basolateral channels - high luminal K+ concentration (transepithelial potential difference)
27
What is legume bloat?
Cattle eat fast growing clover/alfalfa Gas trapped in plant material and doesnt rise to dorsal sac Mechanoreceptor do not detect gas Eructation mechanism fails
28
What must be controlled to maintain fermentation in the hindgut
``` Substrate supply Control of pH Osmolarity Anaerobiosis Retain fermentation material Remove wastes ```
29
What type of protozoa in the forestomach are _________ and belong to genus _______ and _______________
Ciliated; isotricha or entodinium
30
How many recticular-rumen contractions occur per minute
1-3 Rate and strength depend on structure of diet
31
Describe the ruminal environment
Substrate availability : food intake regulates by volume, structure, energy, palatability Temperature: 0.5 to 1 C above body temp Fluid: drink water and saliva pH: 5.5--7 Osmolarity: 260bis>400mOsm/L
32
What are the substrates required for hindgut fermentation?
Carbohydrates and proteins
33
What closes the reticular groove, so milk bypasss the rumen and directly enters the abomasum
Reflex Anticipate suckling and suckling -> CNS -> brainstem -> vagus nerve -> groove contracts forming a tube
34
A ____________ deficiency can be observed when a ruminants diet is suddenly changed from roughage to concentrate
B1 (thyamin)
35
What is the predominant motility pattern of the cecum? How does this differ from the ventral colon?
Cecum: Low-amplitude contractions move ingesta from haustra to haustra (mixing) Ventral colon: haustra segmentation and retropulsive peristalsis (mixing) and propulsive peristalsis (movement)
36
Rumen microbes intake carbohydrates, protein,and lipids to form ?
Volatile fatty acid
37
Microbial lipase hydrolyze fats to ?
Glycerol, sugars, and free fatty acids
38
What is the true stomach in ruminants?
Abomasum
39
What is the largest compartment of the newborn ruminant stomach?
Abomasum Enlargement of the forestomach occurs after birth
40
What volatile fatty acid is the most important precursor for gluconeogenesis of ruminants
Propionate | Will enter Krebs cycle as succinate
41
________ on the surface of microbes generate peptides
Protease
42
What are the two mobility patters on the rumen?
Mixing (primary) Erutation (secondary)
43
What is required for an amino acid to enter the VFA pathway?
Deamination amino acid --> NH3 + carbon skeleton
44
Fatty acids released from fatty acids undergo ____________
Hydrogenation Unsaturated fatty acid -> saturated fatty acid Absorbed in the small intestine
45
What is the product of hindgut fermentation
Volatile fatty acids
46
Carbohydrates digestion in ruminants takes place mostly in the?
Forestomach Almost no digestible carbohydrate enters intestine
47
What is the ratio of VFA in ruminants
Acetic/propionic/butyric acid High forage (fiber) diet-> 70:20:10 High grain (starch) diets -> 60:30:10 The ratio of acetate is lower in the starch diet but the total about produced is greater than the fiber diet
48
What type of digestion occurs in the forestomach of ruminants or in the cecum/colon of horses
Fermentative digestion Digestive enzymes of microbial origin
49
Glycerol and sugars are formed into ______in the rumen microbes
Volatile fatty acids
50
How is calcium reabsorbed int he rumen?
Not well understood Apical- probably Ca/H exchanger Basolateral - Na/Ca exchanger and Ca ATPase
51
When cattle do not have enough oxaloacetate or an excessive amount of acetylCoA, often seen in high-producing dairy cattle, what condition develops?
Ruminant ketosis Acetyl CoA -> acetoacetyl CoA -> ketone bodies (acetoacetate, betahydroxybutyrate, and acetone)
52
What the the function of secondary contractions of the rumen?
Force gas toward the cranial portion of rumen Occurs at end of primary contraction cycle
53
What controls reticulorumen motility
ENS and vagus nerve Stretch receptors/chemoreceptor-> afferent to brainstem (dorsal vagus nucelus)->vagus nerve
54
What component of plants, that increase with age and ambient temperature of the plant is not digestible?
Lignin
55
What major type of lipid is found in cereal grains, oilseeds, animal fats, and byproduct feeds?
Triglycerides
56
What is an example of symbiosis of the ruminant stomach?
Waste products of one species serve as a substrate for another Eg R.albus digests cellulose --> hexose, but not protein B.rumincola detests protein -->fatty acid and ammonia R.albus requires ammonia and fatty acid for growth R.rumincola requires hexose for growth
57
Microbes can synthesize what vitamins
C, K , B
58
What enzyme hydrolyzes cellulose, hemicellulose, and pectin?
Cellulase (in the rumen) Polysaccharide to monosaccharide
59
What are the main gases produced during rumination?
CO2 | Methane
60
What must occur in the fore stomach for glucose, monosaccharides, and short chain polysaccharides to be absorbed by the animal
Microbe uptake Glucose- glycolytic pathway -> 2pyruvate, 2NADH, and 2ATP Anaerobic fermentation digestion to produce volatile fatty acids AKA short chain fatty acid (SCFA)
61
A ________ deficiency can be observed in cobalt poor solids or with diets too high in grain
B12 (cobalamin)
62
Most amino acids following deamination can enter directly into the VFA pathway except for?
Branch-chain aa (BCAA) Eg valine Leucine Isoleucine
63
What major lipid if found in forages?
Glycolipids
64
What are the secondary contractions of the rumen?
Cranial-moving contraction staring in cardio-dorsal blind sac Contraction moves toward cardia forcing gas to esophagus

RUSVM Physio II *TWO* (11 decks)

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