Ruminant GI- Final Exam Material

Question 1

What is a ruminant?

Answer 1

Ruminants are mammals that are able to convert a plants complex carbohydrates (cellulose lignin) into fatty acids and sugars via bacterial fermentation (symbiotic relationship).

Microbes also synthesize vitamins and recycle nitrogen into protein.

The fermenting microbes THEMSELVES are also a moajor nutritioon source for ruminants

Question 2

Where does fermentation occur in the horse?

Answer 2

In the cecem and ascending colon, after the small intestine, hence “hind-gut” fermenter

Question 3

What are the four regions of the ruminant stomach (oral to aboral)?

Answer 3

Rumen
Reticulum
Omasum
Abomasum

Question 4

What is the true, glandular stomach in the ruminant?

Answer 4

abomasum

Question 5

How does the orientation and size of the abdominal viscera change with age and pregnancy in ruminants?

Answer 5

In a newborn calf: large abomasum – important for milk digestion rather than fermentation

In the 5 year old cow: the rumen is large and occupies the entire left side of the abdomen; the liver is pushed cranially

In the 6-year old heavily pregnant cow: the uterus displaces the rumen dorsally and the abomasum cranially

Question 6

Where can you find the rumen?

Answer 6

The entire left side of the abdomen

Question 7

The rumen is divided into various compartments by ______ on the surface of the rumen that correlate with internal _____ on the luminal surface.

Answer 7

grooves; pillars

Question 8

Which side of the rumen is the insula ruminis located on? What grooves create this?

Answer 8

right side only

accessory and longitudinal grooves

Question 9

What are the compartments of the rumen?

Answer 9

Atrium ruminis

Insula ruminis

ventral ruminal sac with ruminal recess

caudoventral and caudodorsal blind sacs

Question 10

What groove divides the atrium ruminis and the reticulum?

Answer 10

ruminoreticular groove

Question 11

What is the intraruminal ostium?

Answer 11

caudal to the insula ruminis

communication between the dorsal and ventral ruminal sac (bound by the right and left longitudinal pillars, and cranial and caudal pillars)

Question 12

What lines the inside of the rumen? How does this lining change with location?

Answer 12

papilla

Papilla are larger ventrally

Question 13

Describe the contents of the rumen.

Answer 13

The rumen contents will vary from gas dorsally to dense liquid ventrally.

Question 14

What is hardware disease and where does it occur?

Answer 14

Trumatic reticulitis or “hardware disease” metal will fall here and can penetrate the diaphragm into the heart. Occurs in the reticulum.

Question 15

How does milk and water bypass the rumen in a calf?

Answer 15

The reticular groove can close to form a tube-like gastric groove to take ingesta from the esophagus to the abomasum.

Question 16

What stimulates the closure of the reticular groove?

Answer 16

ADH

Question 17

What is the sequence of flow if the reticular groove is open?

Answer 17

Cardia - reticular groove -

reticulum - ruminoreticular orifice - rumen - ruminoreticular orifice - reticulum - regurgitation

Question 18

What is the sequence of flow if the reticular groove is closed?

Answer 18

Cardia - reticular groove - reticulo-omasal orifice - omasal groove - omasoabomasal orifice - abomasal groove

Question 19

What makes up the gastric groove?

Answer 19

reticular groove + omasal groove + abomasal groove

Question 20

What do we see in the inside of the omasum?

Answer 20

The omasum is occupied by numerous longitudinal folds, or laminae

Question 21

What structure in the true stomach is unique to the ruminant?

Answer 21

Torus pyloricus located in pyloric region

Question 22

What are the borders of the paralumbar fossa and why is this important?

Answer 22

Base: lumbar transverse processes

Cranioventral border: last rib

Caudoventral border: ridge formed by the part of the internal abdominal oblique muscle that extends from the tuber coxae to the ventral end of the last rib

Access to the rumen and reticulum is gained via the left paralumbar fossa

Question 23

What are the sites of attachment for the greater omentum in the ruminant? Why does this even matter?

Answer 23

Long longitudinal groove of the rumen (superficial leaf)

Right longitudinal groove of the rumen (deef leaf)

The superficial and deep leaves of the greater omentum form a sling within which the bulk of the intestines reside

Question 24

Where are the bulk of the ruminant intestines located?

Answer 24

Within the supraomental recess on the right side

The supraomental recess is bound by the rumen on the left and by the greater omentum on the right

Question 25

What is the main blood supply for the rumen?

Answer 25

Right ruminal artery! This is a branch of the splenic artery.

Question 26

What is the blood supply for the abomasum?

Answer 26

Same as in the dog.

Greater curvature: left and right gastroepiploic aa.

Lesser curvature: left and right gastric aa.

Question 27

What is the major source of innervation for the ruminant stomach?

Answer 27

dorsal and ventral vagal trunk (parasympathetic)

Question 28

Anything special about the duodenum of the ruminant?

Answer 28

Not really.

Question 29

How does the location of jejunal lymph nodes differ between small and large ruminants?

Answer 29

Ox: found in the
mesojejunum between the jejunum and colon

Goat: Minimal distance between jejunum and spiral colon in small ruminant (last centrifugal loop is in between the lymph nodes and jejunum)

Question 30

What makes up the ascending colon of the ruminant?

Answer 30

proximal loop + spiral colon + distal loop

Question 31

What are the components of the spiral colon (oral to aboral)?

Answer 31

Centripetal gyri, central flexure, centrifugal gyri

Question 32

How is the blood supply to the ascending colon of a ruminant different from the dog?

Answer 32

Colic br. of ileocolic a. supplies the first half of ascending colon: proximal loop, centripetal gyri of the spiral loop

Right colic a. supplies the second half of
ascending colon: centrifugal gyri of spiral loop, distal loop