DIGESTIVE SYSTEM DEVELOPMENT AND ANATOMY Flashcards
epithelium of the GIT and parenchyma of glands develops from…
The endoderm
muscle, connective tissue and peritoneum develops from…
The mesoderm
Mesenteries are…
double layers of peritoneum
The stomach rotates … clockwise around its longitudinal axis.
90 degrees
Bile starts being produced from… week
12th
The liver has an important function from 6th week to 7th month:
Hematopoyetic function
From 4th to 6th week, the … has the hematopoyetic function before the livers gets this function.
Splachnic mesoderm from the yolk sac
The liver is originated from the…
Endoderm (mainly), but part of the sinusoids from the liver are developed from the mesoderm.
Bile duct enters in the dudodenum through the…
Major dudodenum papilla
Uncinate process is developed from…
The ventral pancreas
Accessory pancreatic duct is a branch from…
Main pancreatic duct
Lining the abdominal cavity, we have the … mesoderm
Somatic/parietal
Lining the gut tube, we have the … mesoderm
Visceral or splanchnic
What are the mesenteries or mesos?
Double layers of mesoderm which connect the viscera to the walls.
The gut tube is connected to the parietal mesoderm by the…
Mesentery/mesos
Retroperitoneal viscera such as… are fixed and do not move. They are attached to muscles of the posterior abdominal wall such as…
Kidneys
Quadratus lumborum, psoas muscle, transversus abdominis
Intraperitoneal viscera is recovered by … and it is attached to the wall by the …
Visceral peritoneum, mesos.
Mesenteries are also pathways which allow … to access the viscera
Vessels, nerves and lymphatics
Intraperitoneal viscera have some degree of movement (T/F)
True
What kind of viscera is initially Intraperitoneal but becomes retroperitoneal?
2ary retroperitoneal viscera
Example of 2ary retroperitoneal viscera
Pancreas. It will become retroperitoneal and fixed as it loses its mesentery.
Which 3 branches gives the aorta at the level of the abdominal cavity?
- 1st branch for the derivatives of the foregut: CELIAC TRUNK
- 2nd for midgut derivatives: SUPERIOR MESENTERIC ARTERY
- 3rd for hindgut derivatives: INFERIOR MESENTERIC ARTERY
FOREGUT DERIVATIVES
Abdominal esophagus, stomach, 1st and 2nd portion duodenum, pancreas, liver and gallbladder
The derivatives of the foregut are supplied by the….
CELIAC TRUNK
MIDGUT DERIVATIVES + ARTERY AND NERVE WHICH SUPPLIES THEM
Remaining duodenum, jejunum, ileum, cecum/appendix, ascending colon, 2/3 TC
Superior mesenteric artery and vagus nerve
HINDGUT DERIVATIVES + ARTERY AND NERVE SUPPLY
- Remaining 1/3 of the TC
- Descending colon
- Sigmoid colon
- SUPERIOR portion of the rectum
Inferior mesenteric artery+ pelvic splanchnic nerves (S2-S4)
ABDOMINAL AORTA BRANCHES
Parietal branches of the abdominal aorta
Inferior phrenics, lumbar, common iliac, median sacral
Visceral branches abdominal aorta
Celiac trunk (T12-foregut)
Superior mesenteric artery (L1-midgut)
Inferior mesenteric artery (L3-hindgut)
Renal arteries (L1)
Gonadal arteries (L2)
At the level of …, the IVC enters the thorax through the diaphragm.
T8
What is the ENTEROHEPATIC CIRCULATION?
Blood from the digestive system will not go directly into the IVC, but first through the liver.
Portal hepatic vein is formed by…
The junction of splenic vein and superior mesenteric vein
The ICV passes … to the liver
Posterior
GI VENOUS DRAINAGE - PORTAL SYSTEM
A drug taken orally can change its conformations and functions because…
It is metabolised in the liver (1st hepatic effect)
Drugs administered rectally ….
will not pass through the enterohepatic circulation (they are drained into inferior rectal veins, these go directly into the common iliac veins and the IVC).
PS INNERVATION DERIVATIVES FOREGUT AND MIDGUT
Vagus nerve
PS INNERVATION DERIVATIVES HINDGUT
Pelvic splanchnic nerves (S2-S4)
SYMPATHETIC FIBERS arise from …
Lateral horn of the levels T1 to L2
Sympathetic innervation GI SYSTEM
- For foregut and midgut derivatives: greater, lesser and inferior splanchnic nerves.
- For HINDGUT derivatives: lumbar splanchnic nerves.
They synapse in PREAORTIC GANGLIA.
Sympathetic nerves of the GI TRACT will follow ….
The abdominal aorta to reach their corresponding derivatives.
Hiatus of ICV in diaphragm
T8
Esophageal hiatus in diaphragm
T10
Aortic hiatus in diaphragm
T12
Structures passing through the diaphragm
Phrenic nerves, azygos and hemiazygos (which transition into ascending lumbar veins), inferior phrenic arteries
…. Veins drain the derivatives of the midgut and HINDGUT into the portal system
Superior and inferior mesenteric
All the venous drainage from the GI tract enters into the … to become metabolised, and through the … into the IVC
liver, hepatic veins
Primitive gut is formed between the … week of development
4th and 5th
epithelium of the GIT and parenchyma of glands is derived from the …
Endoderm
muscle of the viscera, connective tissue and peritoneum is derived from…
The mesoderm
From the ventral wall of the foregut arises the respiratory diverticulum, which will be separated from the esophagus by the…
TRACHEOESOPHAGEAL SEPTUM
Communication between esophagus and trachea causes:
Esophageal atresia and/or traqueoesophageal fistula
1/3000 births
Prenatal: polyhydramnios
Postnatal: regurgitation
after feeding
Recanalization is a process in which…
There is apoptosis of the growing epithelium/endoderm during the 5th and 6th week
Incomplete recanalization causes…
Stenosis
If the esophagus does not grow properly, the stomach protrudes into the thoracic cavity causing…
CONGENITAL HIATAL HERNIA
Mesenteries are…
double layers of peritoneum
The stomach rotates 90ºclockwise around its longitudinal axis, leaving the … side facing anteriorly and the … portion facing posteriorly.
Left, right
That is why the left vagus nerve comes anteriorly and the right one posteriorly.
The greater curvature of the stomach is cause because…
The posterior wall of the stomach grows faster.
In stomach development, the … is going to move downwards while the …. moves upwards.
Cardiac portion, pyloric portion.
The stomach is connected and attached by…
Mesogastriums
The liver arises and develops in the… mesogastrium
Ventral
The pancreas appears within the … mesogastrium
Dorsal
The spleen develops from…
The mesoderm within the dorsal mesogastrium
Secondary retroperitoneal structures
Duodenum and pancreas
Behind the stomach appears a space, just dorsal to it, which corresponds to …
The omental bursa/lesser sac.
The lesser peritoneal sac and the greater peritoneal sac connect at…
FORAMEN OF WINSLOW (located posterior to the portal vein)
Dorsal mesogastrium grows and gives rise to…
The greater omentum (fat accumulates at the level of the greater omentum).
The greater omentum is 4 layers of mesoderm, separated in 2 and 2 by the space. In the end, the … will become very reduced and small so the 4 layers willl become in contact.
omental bursa space
The liver is not mobile, the …. become ligaments.
mesenteries
Tumours in the …. are difficult for surgery
Lesser sac
The greater omentum in the adult hangs from…., the lesser is attached to the … and connects it to the …
greater curvature, lesser curvature, liver
The 2 double layers of dorsal mesoderm come in contact forming a 4 layered….
Greater omentum
Bike starts to be secreted … week
12th
Liver arises from a liver bud which protrudes into…
The ventral mesogastrium
Ventral mesogastrium will divide into:
- Piece which connects stomach to liver:…
- Piece which connects liver to the ventral wall:….
- Gastrohepatic omentum/lesser omentum
- Falciform ligament
During development, the liver has…
Hematopoietic function
Other functions of the liver
Accumulate glucose in the form of glycogen, produce albumin, carry out protein metabolism, produce and secrete bile.
The bile is stored at the…, and it reaches the duodenum through the…
gallbladder, common bile duct
Together, … and … duct join the pancreatic duct to form the …. which enters the duodenum
hepatic, cystic, common bile duct
The pancreas originates from 2 buds: the … and … pancreatic bud.
The duodenum rotates to the right and forms a C-shaped loop, carrying with it the …. and the … into the dorsal mesentery.
The ventral pancreas arises from the …. Therefore its duct, the main pancreatic duct, will remain connected to the hepatic and cystic ones to enter the duodenum.
The dorsal pancreas’s duct will persist as a little …, which functions when the other is blocked.
- ventral, dorsal
- ventral pancreas, common bile duct
- common bile duct
- accessory pancreatic duct
The main pancreatic duct opens through the … into the 2nd portion of the duodenum, so both hepatic and pancreatic secretions enter here to participate in digestion.
Common bile duct
At the level of the … , a line marks the separation between the derivatives of the foregut and the derivatives from the midgut. It is also the point at which the main pancreatic duct + bile duct drain into the duodenum.
We also find the …., point at which the accessory pancreatic duct drains into the duodenum in case of blockage of the main one.
major duodenal papilla or Ampulla of Vater
minor duodenal papilla
2ary retroperitoneal organs
Pancreas and duodenum
Midgut begins …. and ends at the …
inferior to the major duodenal papilla , junction between the proximal 2/3 and distal 1/3 of the TC.
Midgut includes…
Part of the duodenum, jejunum and ileum, cecum, appendix, ascending colon and the proximal 2/3 of the TC.
Midgut derivatives are supplied by…
Branches of the superior mesenteric artery
The midgut is connected to the abdominal wall by a double layer of mesoderm:
Dorsal mesentery (through which the artery accesses to supply the structures).
Physiological umbilical hernation occurs the … week
Reduction of physiological midgut hernia occurs the … week
- 6th
- 10th
Scheme of midgut development
Anomalies of the midgut
Non-rotation causes:
-Left side colon
Anomalies of the midgut
Midgut volvolus is caused because of…
Twisting of intestines
Anomalies of the midgut
If the second rotation is done clockwise instead of counter-clockwise, the … compresses the colon
SUPERIOR MESENTERIC ARTERY
… is an anomaly in about 2-4% of the population and is cause by the persistence of the vitelline duct (connection with the yolk sac)
If the abdominal musculature does not close properly, part to the small intestine loops to herniate into the umbilicus causing…
UMBILICAL HERNIA (repaired easily)
Failure of the reduction of the physiological umbilical herniation into the abdominal cavity at the 10th week is called …
OMPHALOCELE
If at the 4th week, during the lateral folding of the embryo, the walls do not close properly, part of the visceral in the abdominal cavity can herniate into the amniotic cavity and they will be bathed by amniotic fluid. This condition is known as…
GASTROSCHISIS (severe)
HINDGUT begins ….(after the junction between the proximal 2/3 and the distal 1/3 of the TC) and ends midway through the…
Colic/splenic flexure, anal canal
HINDGUT includes:
Last third TC, descending and sigmoid colon, rectum, upper part of the anal canal.
HINDGUT is supplied by the…
Inferior mesenteric artery
Urorectal septum grows caudally and separates the cloaca into:
And the cloacal membrane into:
It also forms the …, muscles at the pelvic floor
-allantois anteriorly
- rectum and anal canal posteriorly
- urogenital membrane
- anal membrane (proctodeum)
-perineum
Cloacal membrane will give rise to the last portion of the anal canal:
PROCTODEUM
The first 2/3 of the anal canal will derive from the …
HINDGUT (endoderm in origin, IMA, ANS)
The last 1/3 of the anal canal is derived from the …
PROCTODEUM (an invagination of ectoderm from the cloacal membrane, inferior and middle rectal veins, somatic innervation).
The anal membrane will be ruptured at…
8th week
Incorrect development of the urorectal septum causes:
Imperforate anus (persistent anal membrane), recrovaginal fistula, fistula (communication) between ureters and rectum, rectal atresia (cierre)
If there is not migration of the neural crest cells and the large intestine has no PS ganglia, it becomes dilated causing…
MEGACOLON or Hirsprung disease
Superior mesenteric artery arises at…
L1
Jejunum has …. at the mucosa
Prominent folds (for absorption) and lymphoid nodules
Parts of the JEJUNUM
The ileum does not have the … the jejunum has
Prominent folds
Cecum and appendix are …peritoneal
Intra
Ascending colon is …peritoneal
Retro
Transverse colon is …peritoneal
Intra
Sigma is …peritoneal
Intra
Origin of inferior mesenteric vein
Posterior to pancreas
Rectum begins anterior to … level
S3 (at the level of rectosigmal junction)
The end of the rectum is at the …
Tip of the coccyx
Peritoneum in females covers…
Uterus and the rectum partially (sac of Douglas)
Continuity between lesser and greater sac is done by the…
OMENTAL FORAMEN
large apron-like peritoneal fold that
attachs to the greater curvature of the
stomach and first part of the duodenum.
Greater omentum
Remember that it is It consists of a double
sheet of peritoneum, folded on itself so that it
has four layers
The greater omentum fuses with the…
Transverse mesocolon
Greater omentum drapes inferiorly over the … and the ….
transverse colon, coils of the jejunum and ileum
Two-layer peritoneal omentum. It extends from the lesser curvature of the stomach and the first part of
the duodenum to the inferior part of the liver
Lesser omentum
Lesser omentum is divided in … and … ligaments
Hepatoduodenal and hepatogastric
Mesentery: suspends small intestine loops from the …
Posterior wall
Innervation of the peritoneum
THERE IS NO MOTOR INNERVATION AS THERE IS NO MUSCLE
- Visceral afferents: pain travels with sympathetic fibers for thoracic or lumbar splanchnic nerves. Distension with PS fibers from the vagus or pelvic splanchnic nerves.
- Somatic afferents: phrenic nerves and spinal nerves from T6-L2 roughly (well localised pain)
The foregut derivatives are supplied by the… trunk
Celiac
Right vagus nerve is … to esophagus, the left vagus nerve is …
Posterior, anterior
Abdominal esophagus starts at..
T10
IMPORTANTE
Left and right gastric veins drain into the…
PORTAL VEIN
Left gastro-omental vein drains into…
Splenic vein (which joins the superior mesenteric vein to form the portal vein)
Right gastro-omental vein drains into…
The superior mesenteric vein
STOMACH INNERVATION
- Sympathetic: Greater splachnic nerve (T5-T9) + Lesser splachnic nerve (TX-TXI) SYNAPSE IN CELIAC GANGLION
- PS: Vagus nerves