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RUSVM Physiology II > Final Exam GI Physiology: Ruminant Digestion > Flashcards

Final Exam GI Physiology: Ruminant Digestion Flashcards

(56 cards)

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1
Q

What is the principal distinguishing characteristic of ruminant digestion?

A

Fermentation of ingesta by microbes in the ruminoreticulum

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2
Q

What is fermentation?

A

The anaerobic oxidation of substrate followed by reduction of an organic molecule

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3
Q

Lactate formed from pyruvate is an example of what?

A

Fermentation

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4
Q

Methane formed from CO2 is an example of what?

A

Fermentation

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5
Q

Fermentation of amino acids yields what products?

A

Sulfates and Nitrates

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6
Q

What products are produced when sulfates and nitrates are reduced?

A

H2S
NH3
NH4+

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7
Q

In regards to fermentation of carbohydrates, put the following in order from which ferments fastest to which ferments slowest:
Simple sugars
Starches
Cellulose

A

Simple sugars RAPID
Starches MODERATE
Cellulose SLOW

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8
Q

What are the products of fermentation of simple sugars, starches, and cellulose (carbohydrates)?

A 
CO2
CH4
Lactic Acid
VFAs
Acetic Acid
Proprionic Acid
Butyric Acid
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9
Q

T or F: Microbes can perform oxidation in the absence of oxygen.

A

TRUE

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10
Q

What enzyme is utilized by microbes in the rumen to oxidize pyruvate to acetyl CoA?

A

Pyruvate-ferrodoxin oxidoreductase

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11
Q

What enzyme in the rumen acts on the acetyl CoA produced?

A

Phosphotransacetylase

Adds Pi to Acetyl CoA –> Acetyl-Pi and Coenzyme A

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12
Q

What enzyme in the rumen is used by microbes along with ADP to act on Acetyl-Pi produced earlier?

A

Acetate kinase

Acetyl-Pi + ADP —acetate kinase—> acetic acid + ATP

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13
Q

What are the waste products of carbohydrate fermentation?

A

Volatile Fatty Acids!

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14
Q

How do anaerobic microbes generate ATP?

A

By glycolysis and microbe-enzyme reactions in the rumen

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15
Q

In the rumen/reticulum, what are O2 and CO2 ultimately reduced into?

A

H2O and CH4

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16
Q

The ratio of VFA : Lactic acid is a function of ______ .

A

Diet

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17
Q

A low VFA : Lactic Acid (and therefore low rumen pH) ratio is indicative of what kind of diet?

A

High % of easily digestible carbs

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18
Q

What ruminal pH is considered normal?

A

pH of 6

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19
Q

What is a dietary cause of Ruminal Lactic Acidosis?

A

A low VFA : Lactic Acid ratio (caused by too much easily digestible carbs in diet)

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20
Q

What conditions can Ruminal Lactic Acidosis lead to?

A

Ulceration, pain, going off feed, systemic ketoacidosis

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21
Q

How is protein digested in the rumen?

A

Through microbial digestion and hydrolysis via pancreatic and brush border enzymes

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22
Q

What do microbes do to proteins in the rumen?

A

Hydrolysis of protein –> amino acids

Hydrolysis of amino acids —deamination—> VFA

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23
Q

What is generated as a result of amino acid deamination to VFA?

Study These Flashcards
A

AMMONIA (NH3)

24
Q

What is produced Ammonia utilized for?

Study These Flashcards
A

To make microbial protein

To be converted into urea by the liver

25
What % of protein escapes microbial digestion?
50%
26
The 50% of protein that escapes microbial digestion is hydrolyzed in the _______ and _________ via pancreatic and brush border enzymes.
Abomasum and Small Intestine
27
Protein hydrolyzed by pancreatic and brush border enzymes yield what products?
Small peptides and amino acids
28
Where are dead microbes digested?
Abomasum and small intestine
29
Where can urea be found after it is produced by the liver?
Urea can diffuse into GI tract lumen | Urea can be secreted by salivary glands
30
What enzyme converts urea into NH3 (ammonia) and CO2?
Microbial urease
31
How is produced CO2 utilized?
CO2 is used in carboxylase reactions Ex: Pyruvate ---oxaloacetate---> Proprionate
32
What are triacylglycerol and phospholipids hydrolyzed (by microbes) into?
Glycerol and FFA
33
Ruminants characteristically have a _______ level of saturated fat.
HIGH
34
What is produced FFA used for?
Incorporation into chylomicrons
35
What is the fermentation product of glycerol?
VFAs! Specifically proprionic acid
36
All VFAs are _______ acids
All VFAs are carboxylic acids
37
VFAs constitute what percentage of a ruminant animal's daily energy requirement?
70%
38
VFAs constitute 70% of a ruminant animal's daily energy requirement. What is the relative percentage of ACETIC ACID?
60%
39
VFAs constitute 70% of a ruminant animal's daily energy requirement. What is the relative percentage of PROPIONIC ACID?
25%
40
VFAs constitute 70% of a ruminant animal's daily energy requirement. What is the relative percentage of BUTYRIC ACID?
15%
41
VFA's are largely __________ at normal ruminal pH of 6.
NON DISSOCIATED
42
What is the fate of Acetic Acid (a VFA)?
Acetic Acid is converted into Acetyl CoA in muscle and fat.
43
What is the fate of Propionic Acid (a VFA)?
Propionic Acid is REMOVED from plasma by the LIVER
44
What is the fate of Butyric Acid (a VFA)?
Converted to ketone bodies, acetyl CoA, or removed by the liver
45
Is Lactate a volatile fatty acid?
NO. Lactate is NOT a VFA
46
If VFAs constitute 70% of a ruminant's daily energy requirement, what makes up the remaining 30%?
LACTATE
47
What happens to Lactate in circulation?
Lactate is REMOVED from plasma by the LIVER (just like propionic and butyric acids)
48
What happens to Lactate in the liver?
Lactate is converted to PYRUVATE in the liver
49
What happens to Propionate in the liver?
Propionate is converted to SUCCINYL COA in the liver
50
What happens to Butyrate in the liver?
Butyrate is converted to 2 Acetyl CoAs in liver mitochondrion
51
What does an increased concentration of Acetyl CoA in the liver inhibit?
Increased Acetyl CoA in the liver inhibits PDH (pyruvate dehydrogenase) Complex and increases activity of pyruvate carboxylase
52
What is the function of pyruvate carboxylase?
Converts pyruvate into oxaloacetate
53
Which 2 VFA's are converted to TCA intermediates and then Glucose via gluconeogenesis?
Lactate and Propionate
54
Where does the energy come from that supplies the process of turning lactate and propionate into glucose?
The oxidation of Butyrate
55
Almost ALL carbohydrates ingested by ruminants is ________.
FERMENTED
56
Almost NO glucose is ________ by the GI Tract of ruminants.
no glucose absorbed

RUSVM Physiology II (17 decks)

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