Digestive System part 2

small intestine

• it is divided into duodenum, jejunum, and ileum

• it is connected to the dorsal abdominal wall by the dorsal mesentery over its whole length and allows a degree of mobility for other animals except in horse and ruminants (where it is fixed in position by a short mesoduodenum)

horse and ruminants

species where the small intestine is fixed in position by a short mesoduodenum

jejunum

• longest part of the intestine

• most mobile and free part of the alimentary canal

carnivores

species where the jejunum occupies the ventral part of the abdomen between the stomach and the bladder

pig

species where the jejunum is found mainly in the caudoventral part of the right half of the abdominal cavity

ruminants

species where the jejunum is located at the right hald of the abdominal cavity

because the rumen occupies the entire left hald of the abdominal cavity

why is the jejunum of ruminant found in the right half of the abdominal cavity

horse

species where most of the jejunum is found within the left part of the dorsal part of the abdomen

ileum

• it is the short terminal part of the small intestine

ileocecal fold

the distinction between the jejunum and the ileum is defined by the proximal extent of?

ileocecocolic junction of the large intestine

the small intestine terminate into the?

large intestine

it consists of the cecum, colon, and rectum

cecum

• the initial blind part of the large intestine

• generally describes as having a base, body, and apex

• it is attached to the ileum by the ileocecal fold

• base

• body

• apex

parts of the cecum

ileocecal fold

the cecum is attached to the ileum by the?

cats

species where the cecum is small and comma shaped

dog

species where the cecum is s-shaped

• equine

• ruminants

• carnivores

species where the cecum is located at the right side of the abdominal cavity

porcine

species where the cecum is located at the left side of the abdominal cavity

• ruminants

• porcine

species where the cecum is oriented caudally

equine

species where the cecum is oriented cranially

equine

species where the cecum is/has:

• largest, sacculated

• presence of 4 longitudinal bands (dorsal, ventral, lateral, and medial)

ruminants

species where the cecum is cylindrical and non-sacculated

porcine

species where the cecum is/has:

• cylindrical, sacculated

• presence of 3 longitudinal bands with 3 rows of sacculation between them

taeniae

ter3 longitudinal bands in porcine cecum

haustra

term for 3 rows of sacculation

• ascending colon

• transverse colon

• descending colon

these are the 3 portions of the colon

equine

• species wherein the ascending colon is large, arranged in u-shaped loops laying on top of each other

• has these parts:

  • right ventral colon

  • sternal flexure

  • left ventral colon

  • pelvic flexure

  • left dorsal colon

  • diaphragmatic flexure

  • right dorsal colon

• right ventral colon

• sternal flexure

• left ventral colon

• pelvic flexure

• left dorsal colon

• diaphragmatic flexure

• right dorsal colon

parts of equine ascending colon

ruminants

• species wherein the ascending colon is well-developed and is the longest segment of the colon

• has these parts:

  • proximal loop

  • spiral loop (same in pigs)

  • distal loop

• proximal loop

• spiral loop

• distal loop

parts of ruminants ascending colon

porcine

• species wherein the ascending colon is greatly elongates to form a cone-shaped organ

• has these parts:

  • centripetal turns

  • central flexure

  • centrifugal turns

• centripetal turns

• central flexure

• centrifugal turns

parts of porcine ascending colon

carnivores

species where in the ascending colon is short and passes on the right side of the median plane

right ventral colon

• presence of four longitudinal bands (taeniae) with four rows of sacculations (haustra) between them

• connected to sternal flexure

left ventral colon

• presence of four longitudinal bands (taeniae) with four rows of sacculations (haustra) between them

• connected to pelvic flexure

pelvic flexure

• marked reduction in diameter size

• presence of one mesocolic longitudinal band

left dorsal colon

• presence of one mesocolic longitudinal band

• connected to diaphragmatic flexure

diaphragmatic flexure

presence of three (2 dorsal, 1 ventral) longitudinal bands

right dorsal colon

• shortest but widest part (called ampulla coli)

• presence of three (2 dorsal, 1 ventral) longitudinal bands

ampulla coli

shortest but widest part

proximal loop

connected to sigmoid flexure

sigmoid flexure

its first loop is cranially convex and its second loop is caudally convex

spiral loop

• 2 centripetal and 2 centrifugal turns in ox (flat disk appearance)

• 3 centripetal and 3 centrifugal turns in the sheep (low cone appearance)

• 4 centripetal and 4 centrifugal turns in the goat (low cone appearance)

central flexure

separates the centripetal coils and centrifugal coils from each other

• centripetal coils

• centrifugal coils

separated from each other by the central flexure

ox (bovine)

species wherein the spiral loop has 2 centripetal and 2 centrifugal turns and a flat disk appearance

sheep (ovine)

species where the spiral loop has 3 centripetal and 3 centrifugal turns and low cone appearance

goat (caprine)

species where the spiral loop has 4 centripetal and 4 centrifugal turns and has low cone appearance

distal loop

non-sacculated portion of the ascending colon of ruminants

centrifugal turns

have a pearls string appearance in small ruminants - characteristic shape of feces

centripetal turns

• larger, turns clockwise to the apex

• located on the outside of the cone

• marked by two longitudinal bands with two rows of sacculations between them

centrifugal turns

• smaller, turns right counterclockwise

• located inside the cone

• covered by the centripetal turns

carnivores

species wherein the transverse colon runs from the right to left and located to root of the mesentery

equine

species wherein the transverse colon is short and passes from the right to the left cranial root of the mesentery, and marked by two longitudinal bands

carnivores

species wherein the descending colon passes left to the mesenteric root caudally

equine

species wherein the descending colon is:

• long, based on its diameter

• often called as “small colon”

• carries two longitudinal bands (antimesenterial and mesenterial teniae)

• antimesenterial teniae

• mesenterial teniae

two longitudinal bands of the descending colon of equine

rectum

• most dorsal part of the pelvic viscera

• suspended by the mesorectum but the terminal part is retroperitoneal

• becomes dilated to form the rectal ampulla

rectal ampulla

this is formed when the rectum gets dilated

anal canal

• short terminal part of the alimentary canal which opens to the outside with the anus

• it consists of:

  • internal anal sphincter

  • external anal sphincter

internal anal sphincter

• smooth muscle

• a continuation of the smooth circular muscle layer of the rectum

external anal sphincter

striated muscle part of the anal canal

avian

species wherein the duodenum is:

• arranged as a narrow u-shaped loop (duodenal loop) with descending and ascending parts

• closed together by mesentery

• encloses the pancreas

chicken and turkey

avian species wherein the jejunum and ileum are relatively uncomplicated

ducks

avian species wherein the jejunal and ileal loops are separated by axial loops

axial loops

carries near its apex the vitelline diverticulum

adult pigeon

avian species wherein the jejunum and ileum basically form three loops forming a cone-shaped mass with centripetal and centrifugal loops

vitelline diverticulum

a landmark, which is a remnant of the yolk duct, that is found in between the small and large intestines

Meckel’s diverticulum

vitelline diverticulum is formerly known as

avian

species wherein the large intestine is:

• comprised by the ceca and (colo) rectum

• generally, there are left and right long ceca

• the ceca has a heavy muscle coat called cecal sphincter

passerine birds and pigens

avian species that features a very short lymphoid ceca

psittacines and some carnivorous birds

avian specieis wherein the ceca are absent

cloaca

• common digestive and urogenital systems

• the colorectum, ureters, and deferent ducts (or left oviduct) enter the cloaca at various levels

• divided sequentially into coprodeum (feces are stored), urodeum, and proctodeum

• colorectum

• ureters

• deferent ducts (or left oviduct)

these structures enter the cloaca at various levels

• coprodeum

• urodeum

• proctodeum

the cloaca is divided sequentially into:

coprodeum

division of cloaca where feces are stored

bursa of fabricius

• located on the dorsal wall of the proctodeum

• lymphoid tissue in young birds

vent

external opening of the cloaca

liver

• largest gland in the body

• has both exocrine and endocrine function

• equine

• ruminants

species wherein the liver’s relative weight is 1 to 1.5% of the body weight

porcine

species wherein the liver’s relative weight is 2 to 3% of the body weight

canine

species wherein the liver’s relative weight is 3 to 4% of the body weight

feline

species wherein the liver’s relative weight is 2% of the body weight

• equine

• ruminants

• avian

species wherein the right lobe of the liver is undivided

• porcine

• carnivores

species wherein the right lobe of the liver is divided into medial and lateral

ruminants

species wherein the left lobe of the liver is undivided

• equine

• porcine

• carnivores

• avian

species wherein the left lobe of the liver is divided into medial and lateral

avian

species wherein quadrate lobe is absent

• equine

• ruminants

• porcine

• carnivores

species wherein the quadrate lobe is present

• equine

• ruminants

• porcine

• carnivores

species wherein the caudate process of the caudate lobe is present

avian

species wherein the caudate lobe is absent entirely

• equine

• porcine

species wherein the papillary process of caudate lobe is absent

• ruminants

• carnivores

species wherein the papillary process of caudate lobe is present

• ruminants

• carnivores

species wherein the caudate lobe is divided into caudate and papillary process

• equine

• porcine

species wherein the caudate lobe is undivided

equine

species wherein the gallbladder (cholecyst) is absent

• porcine

• carnivores

species wherein the gall bladder is located between the right medial and quadrate lobe

ruminants

species wherein the gall bladder is located between the right lobe and the quadrate lobe

avian

species wherein the gall bladder is carried by the right lobe of the liver