Ruminant GIT #2

Question 1

Greater omentum

Answer 1

• passes caudally from esophagus to rumen over right longitudinal groove, caudal groove, and forward along the left longitudinaly groove, reticulum, and greater curvature of abomasum to duodenum
  -superficial and deep layers which form an omental bursa
  -forms a sling= supraomental recess

Question 2

Lesser omentum

Answer 2

-comes from the lesser curvature of abomasum, covers the omasum and attaches along the liver and duodenum.

Question 3

Post-natal ruminant development

Answer 3

-Birth: abomasal capacity is more than the combined capacity of all other compartments
-Weaning: when young calf begins eating food and mucosa encounters products of microbial fermentation (butyric acid), other compartments begin to grow and balance out with abomasum. Final proportions of stomach compartments are reached at 1 year. Eventually the rumen is the largest

Question 4

Pregnancies effect on abomasum

Answer 4

-gravid uterus slides up underneath the rumen and can lead to the displacement of the abomasum
>displacement and the increased energy demands near the end of pregnancy leading to gas building up and further displacing abomasum

Question 5

Displaced Abomasum

Answer 5

-commonly occurs to the left, but can also occur to the right

Question 6

Pregnancy Toxemia

Answer 6

-ketones build up=toxic
-occurs during pregnancy when the animal has much higher energetic demands but also has less room for rumen. This makes it difficult to meet energy needs.

Question 7

Vasculature of rumen

Answer 7

-Celiac Artery branches to:
1.Splenic
2.Left gastric artery
3.Hepatic artery

Question 8

Splenic artery supply

Answer 8

-right ruminal artery (visceral side and the caudal rumen)
-Left ruminal artery (parietal side and cranial rumen)
-Reticular artery (cardia and reticulum)

Question 9

Left gastric artery supply

Answer 9

-supplies the omasum and fundic part of abomasum along lesser curvature
>accessory reticular supplying ventral reticulum
>left gastro-epiploic supplying the fundus of abomasum

Question 10

Hepatic Artery supply

Answer 10

-Right gastric artery (supplies pylorus of abomasum)
-Gastro-duodenal
-Right gastric-epiploic (supplies pyloric abomasum)

Question 11

Rumen veins

Answer 11

-run satellite to arteries
-gastric and splenic arteries join and open into the portal vein

Question 12

Rumen parasympathetic vs sympathetic innervation

Answer 12

-Parasympathetic: main gastric innervation from vagus nerves
-Sympathetic: from splanchnic nerves

Question 13

Branches of vagus supplying rumen

Answer 13

-dorsal vagal trunk
-ventral vagal trunk

Question 14

Dorsal vagal trunk

Answer 14

-innervates the rumen wall, reticular groove, reticulo-omasal opening, omasum, and abomasum

Question 15

Ventral dorsal trunk

Answer 15

-innervates atrium ruminis, reticular groove, omasum, and right face of abomasum

Question 16

Sensory receptors of the rumen

Answer 16

-mostly located in reticulum and abomasum
-both mechanoreceptors (pressure and tension) and chemoreceptors (pH and metabolites)

Question 17

Rumen movements

Answer 17

1.Primary (mixing)
2.Secondary (gas eructation)
3. Rumination (regurge of food)

Question 18

Functions of rumen movements

Answer 18

-mechanical breakdown
-mixing of ingesta with microbes
-mixing saliva to buffer VFAs
-prevention of local accumulation of VFAs
-absorption of VFAs
-elimination of gases produced by fermentation

Question 19

Contraction auscultation

Answer 19

-biphasic reticular contraction can be auscultated at middle of 6-8 intercostal spaces on the left side of single contraction
-Dorsal sac contraction occurs in cranio-caudal direction in paralumbar fossa. Followed by ventral sac contraction

Question 20

Regurgitation of food

Answer 20

-occurs after reticular contraction
-the ingesta is drawn into esophagus by inspiration against closed glottis and carried orally by antiperistaltic waves
-heavily broken down cud will drop from cardia to reticulum

Question 21

Eructation

Answer 21

-discharge of gas through esophagus (some through mouth but most to lungs)
-no reticular contraction occurs during eructation
-ruminal movement originates at ventral sac and then dorsal sac extending caudo-cranially ‘

Question 22

Omasum movements

Answer 22

-biphasic contraction
>first contraction squeezes ingesta from omasal canal into the recesses between omasal laminae
>Second contraction is a mass contraction squeezing fluid from within the recesses

Question 23

Abomasum movements

Answer 23

-sluggish movement
-more powerful peristalsis occurs towards pyloric part

Question 24

Primary contraction

Answer 24

-Reticulum-biphasic contraction. The second reticular contraction floods the cardia prior to inspiratory effort. Rapid peristaltic wave transports cud up to pharynx for remastication

Question 25

Secondary contraction

Answer 25

-cranial movement/contraction in the caudodorsal and caudoventral sacs, and ventral sac causing the gas pocket to move towards the cardia to be released

Question 26

Intestinal mass

Answer 26

-to the right of midline
- approx. 50m long in adult
-suspended by great mesentery
-lies within the supra-omental recess

Question 27

Bovine large intestines

Answer 27

-left fact of mesentery
-1.5-2 turns making up 95% of intestines

Question 28

Ruminant duodenum

Answer 28

-originates from pylorus below costal arch
-passes dorsally to form s-shaped curve along liver
-attached to liver by lesser omentum
-bile duct opens into descending duodenum; pancreatic duct opens further down the descending duodenum
**small ruminants usually have both opening in common

Question 29

Ruminant Jejunum

Answer 29

-position depends on the fullness of the rumen
-mostly lies within the supraomental recess

Question 30

Ileum

Answer 30

-extent defined by ileocecal fold
-opens into cecum on a low ileocecal papilla

Question 31

Cecum

Answer 31

-demarcated from colon only by site of ileocecal opening
-non-sacculated and blind ended sac

Question 32

Ascending colon

Answer 32

-sigmoid flexure as it leaves cecum
-has proximal and distal loops
-double spiral middle segment: 2 centripetal and 2 centrifugal

Question 33

Transverse colon

Answer 33

-crosses midline cranial to mesenteric root to give rise to descending colon on left

Question 34

Descending colon

Answer 34

-to the left of mesenteric root, attached to ascending duodenum
-slack in this region facilitates transrectal palpation

Question 35

Rectum

Answer 35

-muscular walls, wide, impermanent transverse folds

Question 36

Anus

Answer 36

-internal and external anal sphincters
-pelvic and urogenital diaphragm
-perineum

Question 37

Intestinal lymph nodes

Answer 37

-Peyer’s patches (SI, and ileum)
-Jejunal lymph nodes
-All lymph nodes drain into cysterna chyli

Question 38

Intestines blood supply

Answer 38

-Arterial: Cranial mesenteric artery- supplies majority of intestines except cranial part of duodenum (which is supplied by celiac artery) and descending colon and rectum (which is supplied by caudal mesenteric artery)
-Veins: Cranial mesenteric vein empties into portal vein