lab 16 gastrointestinal physiology

Question 1

how is a rumen fistula made?

Answer 1

an oblong opening is made in the left flank; the muscle and peritoneum are split. the rumen wall is pulled directly through the opening where it is sutured tightly to the skin layer. once completed, the center portion of the rumen wall is cut away, leaving a circular opening for the insertion of the fistula.

Question 2

is the rumen completely full?

Answer 2

no

Question 3

what would happen if the rumen were completely full?

Answer 3

mixing could not occur properly;

Question 4

what is the normal pH of the rumen?

Answer 4

6.8?

Question 5

what is the significance of the granules in some of the larger protozoa?

Answer 5

they sequester starch and this helps make fermentation slower and more even

Question 6

what is the sequence of events of a primary contraction?

Answer 6

there is a double reticular contraction; the last contraction contiunes spreading from the reticulum and passes to the omasum. it also passes to the dorsal sac of the rumen and continues into the blind sac of the caudal rumen; a slower wave travels through the ventral sac after this dorsal sac contraction from cranial to caudal and then from caudal to cranial.

Question 7

how often do primary contractions occur in general?

Answer 7

they occur every 40-60 seconds

Question 8

how often do primary contractions occur when an animal is eating?

Answer 8

every 40 seconds

Question 9

how often do primary contractions occur when an animal is ruminating

Answer 9

every 50-60 seconds

Question 10

how often do primary contractions occur when an animal is resting

Answer 10

every 70 seconds

Question 11

what is the function of the primary contraction?

Answer 11

to mix the digesta within the rumen and assist with the movement of the fine particles into the omasum

Question 12

where should you listen to rumen contractions?

Answer 12

in the left paralumbar fossa

Question 13

what generates the sounds that you hear on listening to rumen contractions?

Answer 13

ingesta rubbing the walls

Question 14

what sac are you hearing when you listen at the paralumbar fossa?

Answer 14

the dorsal sac

Question 15

what is the role of secondary contractions?

Answer 15

they assist the animal in eructating rumen gases

Question 16

what is the sequence of events of a secondary contraction?

Answer 16

the dorsal blind sac travels in a cranial direction toward the cardia or entrance of the esophagus
the the dorsal sac contracts caudal to cranial, then the ventral sac contracts caudal to cranial.

Question 17

how much gas from eructation travels into the lungs?

Answer 17

60%

Question 18

how much gas from eructation makes it out the mouth

Answer 18

40%

Question 19

when do secondary contractions occur?

Answer 19

they usually follow primary contractions

Question 20

how many contractions should one hear a minute?

Answer 20

2: a primary contraction and a secondary contraction

Question 21

how does regurgitation occur?

Answer 21

it occurs just before a primary contraction. the reticulum begins contracting and lifts contents to cover the cardia; at the peak of contraction the animal inhales against a closed glottis. the cardia relaxes and the negative pressure draws or sucks rumen contents in; reverse peristalsis occurs

Question 22

what occurs when the rumen is artificially bloated?

Answer 22

the left side expands first; increases rumen pressure stimulates tensio nreceptors and slows rumen contraction;

Question 23

where would you find a magnet when giving it to an animal for prevention of hardware disease?

Answer 23

in reticulum or rumen

Question 24

why does a magnet help reduce the incidence of hardware disease?

Answer 24

prevents objects from piercing the rumen wall