Anatomy Exam 5: Development Of Digestive System

Front 1

Obj.
Describe the incorporation of yolk sac endoderm into the primitive gut as a result of cephalocaudal and lateral folding of the trilaminar germ disc.

Back 1

cephalocaudal (longitudinal) and lateral (transverse) folding moves the yolk sac from caudal to more cephalad and central in the embryo, eventually segmenting into the primitive gut

Front 2

As a result of lateral and cephalocaudal folding the _________ & ______________ remain outside the embryo

Back 2

distal portion of yolk sac & allantois

Front 3

The primitive gut is divided into:
________ that begins at the buccupharyngeal membrane,
________ connected to the yolk sac by the vitelline duct, and
________ that ends at the cloacal membrane.

Back 3

foregut

midgut

hindgut

Front 4

Describe the location of the regions of the primitive gut:
Pharyngeal gut
Foregut
Midgut
Hindgut

Back 4

Pharyngeal gut- from buccopharyngeal membrane to respiratory diverticulum

Foregut- from respiratory diverticulum to liver bud

Midgut- distal to liver bud to left colic (splenic) flexure

Hindgut- from left colic flexure to cloacal membrane

Front 5

Obj.
Discuss the blood supply and adult derivatives of the foregut, midgut, and hindgut.

Back 5

Foregut- celiac trunk

Midgut- superior mesenteric artery

Hindgut- inferior mesenteric artery

Front 6

Obj.
Describe the contributions of endoderm and splanchnic mesoderm in development of the digestive tract.

Back 6

Endoderm- forms the epithelial lining of the gut & gives rise to the parenchyma of glands

Splanchnic mesoderm- forms smooth muscle, connective tissue, & visceral peritoneum of gut wall

Front 7

Portions of the gut tube are suspended by the ______________

Back 7

mesentaries

Front 8

Organs that are suspended from the posterior body wall by mesentary & invaginate the peritoneal sac are (intraperitoneal/retroperitoneal)?

Back 8

intraperiotoneal

Front 9

Organs that lie against the posterior body wall & are only partially covered by the parietal peritoneum are (intraperitoneal/retroperitoneal)?

Back 9

retroperitoneal

*usually covered on their anterior surface be peritoneum

Front 10

Organs that are temporarily intraperitoneal but later become retroperitoneal are referred to as what?

Back 10

secondarily retroperitoneal

Front 11

What are peritoneal ligaments?

Back 11

double layers of peritoneum that pass from one organ to another or from an organ to the body wall

(may carry vessels & nerves)

Front 12

what are the subdivisions of the dorsal mesentery at the 5th week of development?

Back 12

-dorsal mesogastrium/greater omentum (stomach region)
-dorsal mesoduodenum
-mesentary proper (region of jejunum & ileum)
-dorsal mesocolon (colon region)

Front 13

The _________ becomes a peritoneal fold that attaches the greater curvature of the stomach & hangs over the transverse colon & loops of jejunum & ileum

Back 13

greater omentum

Front 14

The ______________ is present only in the region of the abdominal esophagus, stomach, & upper duodenum

Back 14

ventral mesentary

Front 15

As the liver grows into the septum transversum it divides the ventral mesentery into what 2 things?

Back 15

falciform ligament & lesser omentum

Front 16

The falciform ligament contains the ____________ w/i its free lower margin, which will form the ligamentum teres hepatis after birth

Back 16

umbilical vein

Front 17

The lesser omentum connects the lesser curvature of the stomach via _____________________________
and the first part of the duodeunum via ______________________

Back 17

hepatogastric ligament

hepatoduodenal ligament
^ contains portal triad

Front 18

The hepatoduodenal ligament (right free margin of lesser omentum) also forms the anterior border of the ________________, which connects the omental bursa to the greater peritoneal sac.

Back 18

omental (epiploic) foramen

Front 19

The esophagus has skeletal muscles from pharyngeal arches innervated by __________________ and smooth muscle innervated by ______________________.

Back 19

vagus nerves

parasympathetic fibers of the esophageal plexus (also from vagus nerves)

Front 20

Obj.
Discuss esophageal (and/or tracheoesophageal fistula)

Back 20

Esophagus ends in blind pouch and/or is connected to the trachea (fistula)
-due to the deviation of the tracheoesophageal septum
-may result in polyhyrdamnios

Front 21

Obj.
Discuss esophageal stenosis

Back 21

narrowing of the esophagus
-due to incomplete recanalization following an epithelial proliferation phase

Front 22

Obj.
Describe a congenital hiatal hernia

Back 22

part of the stomach is pulled up through the esophagueal hiatus of the diaphram
-due to congenitally short esophagus

Front 23

Obj.
Describe rotation of the stomach and its consequences.

Back 23

-Initially stomach develops as a fusiform swelling of gut
-first rotates 90 degrees around longitudinal axis
--> original L side becomes anterior
-then rotates 90 degrees around anterioposterior axis----> lesser curvature faces up/R & greater faces down/L

Front 24

Due to rotation of the stomach during development, the left vagus nerve forms most of _________________
& the right vagus nerve forms most of ______________

Back 24

anteriorvagal trunk (left)

posteriorvagal trunk (right)

Front 25

What part of the stomach is connected to the esophagus via the gastroesophageal junction?

What part is continuous w/ the duodenum?

Back 25

cardial portion (most proximal)


pyloric part (most distal)

Front 26

As the stomach rotates, the dorsal mesogastrium is pulled (right/left) creating the ________________, behind the stomach & lesser omentum.

Back 26

left

omental bursal

Front 27

Obj.
Describe development of the spleen

Back 27

-develops from mesoderm of dorsal mesogastrium
-is divided into gastrosplenic (gastrolienal) & splenorenal (lienorenal)ligaments
-the spleen is intraperiotneal

Front 28

The ___________ enters the splenorenal ligament, where it is in danger during splenectomy

Back 28

tail of pancreas

Front 29

The duodenum forms a C-shape around the head of the pancreas. The proximal part, to the origin of the liver bud, develops from the _____________ & the distal part from the ______________

Back 29

foregut

midgut

Front 30

The dorsal mesoduodenum disappears from all of the duodenum except for what part?

Back 30

duodenal cap (ampulla)

**therefor most of duodenum = secondarily retroperitoneal

Front 31

Obj.
Discuss congenital pyloric stenosis and duodenal atresia and how their presentations may differ.

Back 31

congenital pyloric stenosis:
*non-bile stained projectile vomiting
-results from hypertrophy of smooth muscle pyloric sphincer
-results in obstructed passage of food from stomach to duodenum

duodenal atresia (stenosis):
*bile stained projectile vomiting
-results from incomplete recanalization of duodenum, occurs shortly after birth
-results in "double bubble sign" (shown in ultrasound scan)

*polyhydraminos present in both*

Front 32

Obj.
Describe the development of the liver

Back 32

-begins as hepatic diverticulum/liver bud on the duodenum
-grows into the septum transversum
-remains connected to the duodenum via bile duct once fully developed

Front 33

Obj.
Describe the development of the gallbladder.

Back 33

The gallblader & cystic duct develop from a small ventral outgrowth on the hepatic diverticulum/liver bud

Front 34

Obj.
Describe the development of the pancreas.

Back 34

-initally an endodermal proliferation off the liver bud, the ventral pancreatic bud & dorsal pancreatic bud in dorsal mesoduodenum
-as duodenum rotates the ventral bud moves dorsally & fuses w/ dorsal bud
-ventral bud forms the unicate process & inferior part of the head
-dorsal bud forms remainder of pancreas

Front 35

Which portion of the pancreas do the main & accessory ducts form from?
Where do they open?

Back 35

main pancreatic duct (of Wirsung):
-develops from distal dorsal pancreatic duct & entire ventral pancreatic duct
-opens at major duodenal papilla

accessory pancreatic duct (of Santorini):
-develops from proximal part of dorsal pancreatic duct
-opens at the minor duodenal papilla

Front 36

The hepatic diverticulum forms epithelial cords that differentiate into glandular__________________, enclosing ___________ formed mainly by the vitelline veins.

Back 36

glandular parenchyma (hepatic cells)

enclosing hepatic sinusoids

Front 37

The connective tissue framework of the liver (stroma) develops from what?

Back 37

mesoderm of the septum transversum

Front 38

What important function does the liver have from 6wks-6mnths of fetal development?

What specific cell of the fetal liver perform this function?

Back 38

hematopoietic function (blood production)


performed by hematopoietic stem cells located in the aorta-gonad-mesonephros region

Front 39

At 12wks, the liver also begins to perform what function?

Back 39

bile secretion
*excess bile is stored & concentrated in pancreas

Front 40

obj
Discuss the following:
extrahepatic biliary atresia

Back 40

-hepatic or bile duct fails to recanalize following phase of epithelial proliferation

Front 41

obj
Discuss the following:
annular pancreas

Back 41

2 components of the ventral pancreatic duct migrate in opposite directions & encircle the duodenum

-may obstruct duodenum

Front 42

The midgut communicates w/ the yolk sac via the _______________
It is supplied by the __________________ artery

Back 42

vitelline duct

Superior mesenteric artery

Front 43

Obj.
Describe the rotation of the midgut and the portions of the digestive system that become secondarily retroperitoneal as a result.

Back 43

-The midgut rapidly elongates during development forming the primary intestinal loop
-primary intestinal loop has 2 limbs, cephalic & caudal
-cephalic limb forms distal duodenum, jejunum, & part of ileum
-caudal limb forms lower ileum, cecum, appendix, & ascending colon, & proximal 2/3 of transverse colon
-as the primary loop grows it rotates 270 degrees clockwise around the superior mesenteric artery & enters the umbilical cord bc the abdomen is too small
-during 10th week it returns to enlarged abdomin
-in final location, the caudal limb intestines are secondarily retroperitoneal & cephalic are intraperitoneal

Front 44

Obj.
Describe physiological herniation of the midgut

Back 44

Physiological umbilical herniation occurs due to rapid growth of the liver & intestines. The abdominal cavity is too small to fit both the liver & intestines, so the intestinal loop enters the umbilical cord
*normally returns to abdomen once it enlarges

Front 45

The appendix develops from the ________ as a result of colon descent from right upper quadrant to right lower quadrant

Back 45

cecal bud

Front 46

When the ascending & decending colons reach their final position, their mesentaries fuse w/ the peritoneum of the posterior abdominal wall, making them ___________________

Back 46

secondarily retroperitoneal

Front 47

The mesentaries of the jejunum & ileum obtain new attachments (root of mesentery) from the _________________ to the ____________)

Back 47

duodenojejunal to the ileocecal junction

Front 48

The transverse colon (suspended by transverse mesocolon) and sigmoid colon (by sigmoid mesocolon) both remain ___________

Back 48

intraperitoneal

Front 49

obj
Discuss the following anomalies:
sigmoid volvulus.

Back 49

cecal (sigmoid) volvulus- mesentery of the lower ascending colon fails to fuse w/ posterior body wall & the cecum becomes twisted on it

Front 50

The hingut forms the distal 1/3 of the transverse colon, the descending colon, sigmoid colon, rectum, upper anal canal, & ends in the ______________
What is the hindgut supplied by?

Back 50

cloaca

inferior mesenteric artery

Front 51

The _____________ is a common chamber of the urinary & digestive system

Back 51

cloaca

Front 52

Obj.
Describe the division of the cloaca by the urorectal septum and the clinical significance of the pectinate line.

Back 52

-The urorectal septum divides the cloaca into an anterior urogenital sinus & posterior anorectal canal
-The pectinate line divides the anal canal into a cranial & caudal portion
-The cranial portion of the canal develops from endoderm & the caudal from ectoderm
-The cranial & caudal portions have SEPARATE innervation, blood supply, & lymph drainage
= infections, cancer, etc does not spread btwn 2

Front 53

Differentiate btwn imperforate anus & urorectal or rectovaginal fistuala

Back 53

imperforate anus:
-failure of recanalization of lower anal canal following epithelial proliferation
=no anal canal present

urorectal or rectovaginal fistuala::
-opening of hingut shifts anteriorly bc urorectal septum does not extend far enough caudally
=no opening to anal canal

Front 54

Obj.
Discuss what digestive tract disorders are likely to be associated with polyhydramnios and why.

Back 54

-congential pyloric stenosis
-duodenal atresia
-esophageal atresia

Front 55

obj
Discuss the following anomalies:
congenital megacolon (Hirschsprung's disease)

Back 55

-autonomic (parasympathetic) ganglia are absent from a segment of the intestine
-dilated "mega" section forms proximal to the segment lacking ganglia