Abdomen 2b: Gastrointestinal Tract - Dr. Inpanbutr

The gastrointestinal tract develops from a embryonic primitive gut tube called the what?

endoderm

Three parts of endoderm:

1.) foregut

2.) midgut

3.) hindgut

The foregut of the endoderm differentiates into (4)

1.) pharynx

2.) esophagus

3.) stomach

4.) first part of duodenum

The midgut of the endoderm differentiates into (5)

1.) distal part of duodenum

2.) jejunum

3.) ileum

4.) cecum

5.) larger part of the colon

The hindgut of the endoderm differentiates into (3)

1.) distal part of the colon

2.) rectum

3.) part of the urogenital tract

The gastrointestinal tract includes (3):

1.) stomach

2.) small intestines

3.) large intestines

Stomach

musculoglandular organ interposed between the esophagus and the small intestine

The stomach is the largest __________ of the GI tract

dilation

Function of the stomach (3)

1.) produce mucus and gastric enzymes

2.) produce muscular movements to mix ingesta and enzymes, aiding in digestion

3.) slowly move ingesta into the duodenum

Four parts of the stomach:

1.) cardiac

2.) fundus

3.) body

4.) pylorus

When the stomach is empty, is it hidden from palpation by what cranioventrally (2)?

liver and diaphragm

When the stomach is empty, is it hidden from palpation by what caudally?

intestinal mass

When the stomach is full, it protrudes beyond the...

costal arches

The full stomach can extend caudally to what point?

L3-L4 vertebrae

Rugae

folds of the stomach wall

Cardiac part of the stomach

the smallest part of the stomach situated near the esophagus

The cardiac part of the stomach is located at the ________ ____ intercostal space

left 9th intercostal space

Fundus of the stomach

dome-shaped portion of the stomach that produces gastric juice

Where does the fundus of the stomach lie in relation to the cardiac part of the stomach?

to the left and dorsal to the cardiac part

Body of the stomach

large middle portion of the stomach that extends from the fundus on the left to the pyloric part on the right; produces gastric juice

Pyloric part of the stomach

distal third of the stomach that produces mucus

Three parts of the pyloric part of the stomach:

1.) pyloric antrum

2.) pyloric canal

3.) pylorus

pyloric antrum

thin walled part of pylorus that narrows into the pyloric canal

pyloric canal

narrow of the pyloric part of the stomach as it enters the duodenum

pylorus

sphincter between the pyloric part of the stomach and the duodenum

Which part(s) of the stomach produce gastric juices?

fundus and body

Which part(s) of the stomach produce mucus?

pyloric part of the stomach

1

cardiac part of the stomach

2

fundus of the stomach

3

body of the stomach

4

pyloric part of the stomach

4a

pyloric antrum

4b

pyloric canal

5

pylorus

Small intestines

principal site of digestion and absorption, extending from the pylorus of the stomach to the large intestine

three parts of the small intestines:

1.) duodenum

2.) jejunum

3.) ileum

Duodenum is the most _______ part of the small intestines

fixed

Since the duodenum is the most fixed part of the small intestines, does this make it more or less likely to be displaced?

less

The duodenum is divided into five segments:

1) cranial duodenal flexure

2) descending duodenum

3) caudal duodenal flexure

4) ascending duodenum

5) duodenojejunal flexure

cranial duodenal flexure

first bend of the duodenum near the pylorus

descending duodenum location

courses caudally on the right side of the abdominal cavity

the descending duodenum contacts the _________ part of the abdominal cavity

dorsolateral

The descending duodenum has three features:

1.) mesoduodenum

2.) major duodenal papilla

3.) minor duodenal papilla

mesoduodenum

mesentery that attaches the duodenum to the body wall

major duodenal papilla

opening of pancreatic & bile duct

minor duodenal papilla

opening of accessory pancreatic duct

caudal duodenal flexure

aka transverse duodenum; duodenum begins to travel towards the left side of the body

the caudal duodenal flexure occurs at the level of which vertebra?

L6 vertebra

ascending duodenum location

travels cranially on the left side of the root of the mesentery

duodenojejunal flexure

the junction between the duodenum and jejunum

The jejunum is the ________ part of the small intestine

longest

The jejunum occupies a large portion of the __________ abdomen

caudoventral

the jejunum is covered ventrally and laterally by what structure?

greater omentum

The jejunum is supported by the __________

mesojejunum

mesojejunum

mesentery that attaches the jejunum to the root of the mesentery

The mesojejnum spans from the __________ _________ __________ to the _________ _________ _______

dorsal abdominal midline; 2nd lumbar vertebra

The root of the mesentery is located at the

2nd lumbar vertebra

The root of the mesentery contains (3):

1.) cranial mesenteric artery

2.) nerves

3.) mesenteric lymph nodes

the ileum is the _________ part of the small intestine

shortest

The ileum opens into the ascending colon at the level of the

first or second lumbar vertebrae

Three features of the ileum:

1.) ileocolic orifice

2.) ileocolic sphincter

3.) ileocecal fold

ileocolic orifice

where the ileum empties into the colon

ileocolic sphincter

smooth muscle sphincter that regulates the flow of ingesta through the ileocolic orifice

The ileum is connected to the _______

cecum

The ileum is connected to the cecum through the...

ileocecal fold

The ileum is suspended by (2):

1.) mesentery

2.) mesocolon

Which artery is located parallel along the ileum?

antimesenteric ileal a.

1 (behind ribs)

cranial duodenal flexure

2

descending duodenum

3

caudal duodenal flexure

4

ascending duodenum

5

duodenojejunal flexure

1

cranial duodenal flexure

2

descending duodenum

1

jejunum

R

root of the mesentery

1

ileum

2

ascending colon

1

cecocolic orifice

2

ileocolic orifice/ileocolic sphincter

3

ileocecal fold

large intestines

extends from the ileum to the anus

large intestines function

dehydrate fecal contents by absorbing water

three parts of the large intestines

1.) cecum

2.) colon

3.) rectum

cecum

a blind diverticulum at the beginning of the colon

The cecum lies to the ________ of the root of the mesentery

right

What shape is the cecum in the dog? Cat?

dog: "S" shaped

cat: "comma" shaped

Two features of the cecum:

1.) cecocolic orifice

2.) cecocolic sphincter

cecocolic orifice

where the cecum communicates with the ascending colon

the cecocolic orifice is adjacent to the __________ orifice

ileocolic

cecocolic sphincter

regulates the passage of contents through the cecocolic orifice

The cecum in the cat can be palpated at the level of which vertebra?

4th vertebra

Colon

slightly wider section than the small intestine; located after the cecum

The colon is located _________ in the abdomen

dorsally

The colon is suspended by __________

mesocolon

The colon is divided into three parts:

1.) ascending colon

2.) transverse colon

3.) descending colon

Ascending colon location

to the right of the root of the mesentery

right colic flexure

bend between the ascending and transverse colon

Transverse colon location

lies cranial to the root of the mesentery

left colic flexure

bend between the transverse and descending colon