TBL 16

Question 1

What is the peritoneal cavity? What is the function of peritoneal fluid?

Answer 1

•peritoneal cavity: space between parietal peritoneum and visceral peritoneum present within the abdominal cavity
•contains peritoneal fluid: composed of water, electrolytes, and other substances derived from interstitial fluid in adjacent tissues
•function of peritoneal fluid:
-lubricates the peritoneal surfaces so viscera can move over each other without friction → allowing movements for digestion
-contains leukocytes and antibodies: resists infection
•lymphatic vessels below the diaphragm: absorb the peritoneal fluid

Question 2

What is the difference in the structure of peritoneal cavity between males and females?

Answer 2

•peritoneal cavity is completely closed in males but in females there is communication from exterior of the body through the uterine tubes, uterine cavity, and vagina; potential pathway for infection

Question 3

Why can peritonitis be lethal and why is the linea alba a preferred site for ascites paracentesis?

Answer 3

Peritonitis:
•due to gas, fecal matter, and bacteria entering peritoneal cavity which results in infection and inflammation of the peritoneum
•it can become lethal because high amounts of peritoneal surfaces and rapid absorption of material including bacterial toxins from the peritoneal cavity
•symptoms: severe abdominal pain, tenderness, naseau, vomiting, fever, constipation

Paracentesis:
•Surgical puncture of peritoneal cavity for aspiration and drainage of the fluid at the linea alba (bloodless and avoids major nerves)
•Needle is inserted superior to the empty urinary bladder in a location that avoids the inferior epigastric artery

Question 4

How can peritoneal adhesions cause emergency complications?

Answer 4

• When peritoneum becomes damaged, the peritoneal surfaces become inflamed making them sticky with fibrin → fibrin becomes fibrous tissue which forms abnormal attachments between adjacent visceral peritoneum or between visceral peritoneum and parietal peritoneum → this limits the normal movement of the viscera
• Symptoms: may cause chronic pain or intestinal obstruction when intestine becomes twisted around an adhesion
• Adhesiotomy: surgical separation of adhesions

Question 5

what are example of organs that are intraperitoneal and retroperitoneal?

Answer 5

intraperitoneal organs: stomach, spleen, intestines: completely protrude into the parietal peritoneum and are surrounded by visceral peritoneum
retroperitoneal organ: kidneys: do not protrude into the peritoneum and parietal peritoneum cover the anterior surfaces

Question 6

How are mesenteries formed and what is its function?

Answer 6

• mesenteries: continuity of visceral and parietal peritonea that extend from the intraperitoneal organs into the parietal peritoneum
• mesenteries enclose branches of abdominal aorta (retroperitoneal) and IVC

Question 7

Distention/irritation of parietal peritoneum causes what type of pain…

Answer 7

•distention/irritation of parietal peritoneum activates sensory fibers causing sharp, localized pain

Question 8

Describe the greater ommentum.

Answer 8

•greater omentum: four-layered peritoneal fold that hangs from the greater curvature of the stomach and proximal part of duodenum and then folds back and attaches to the anterior surface of the transverse colon and its mesentery

Question 9

How do functions of the greater omentum relate to its common displacement in the peritoneal cavity?

Answer 9

-greater omentum prevents the visceral peritoneum from adhering to parietal peritoneum → has considerable mobility and moves around the peritoneal cavity with peristaltic movements; it also cushions the abdominal organs against injury and forms insulation against heat loss

Question 10

Describe the lesser momentum.

Answer 10

•lesser omentum: double layered peritoneal fold that connects the lesser curvature of stomach and proximal part of duodenum to the liver

Question 11

How does the phrenic nerve provide an exception to the concept that pressure applied to the parietal peritoneum results in sharp, localized pain?

Answer 11

o Pain from the parietal peritoneum is well localized except on the inferior surface of the central part of diaphragm where it is innervated by the phrenic nerve; irritation here is referred to C3-C5 dermatomes over the shoulder

Question 12

Describe the greater sac and its compartments.

Answer 12

• greater sac: largest part of peritoneal cavity
• transverse mesocolon: mesentery of the transverse colon divides the greater sac into supra colic compartment and infra colic compartment
• there are right and left parabolic gutters which provides free communication between the compartments

Question 13

How do ascites and cancer cells spread within the peritoneal cavity?

Answer 13

-paracolic gutters: clinically important because it provides pathways for the flow of ascitic fluid and spread of intraperitoneal infections; also provide pathways for the spread of cancer cells that have sloughed off from ulcerated surface of tumor and enter peritoneal cavity

Question 14

Describe the lesser sac.

Answer 14

Lesser sac (omental bursa): lies posterior to the stomach and lesser omentum

Question 15

What does the omental foramen do?

Answer 15

-it connects the greater and lesser sac

Question 16

Connective tissue and smooth muscle of gut tube are derivatives of…

Answer 16

-connective tissue and smooth muscle of tubular wall are derivatives of visceral mesoderm

Question 17

What are the foregut derivatives and what arteries supply them?

Answer 17

foregut derivatives:
•esophagus, stomach, proximal duodenum
•endoderm buds from proximal duodenum and gives rise to gallbladder, liver, pancreas
•supplied by the celiac artery
•drained by celiac lymph nodes

Question 18

What are the midgut derivatives?

Answer 18

• lower duodenum, jejunum, ileum, cecum, appendix, ascending colon, proximal 2/3 transverse colon
• supplied by the superior mesenteric artery

Question 19

What are the hind gut derivatives?

Answer 19

hindgut:
•distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper anal canal, urogenital sinus
•supplied by the inferior mesenteric artery

Question 20

What are the vascular derivatives of the right and left vitelline veins?

Answer 20

• the left and right vitelline veins enter the septum transversum to form hepatic sinusoids and hepatic veins
• after formation of the left-to-right venous shunt, distal portion of the left vitelline vein disappears and right vitelline vein becomes portal vein and superior mesenteric vein

Question 21

Define the drainage field of the hepatic portal vein.

Answer 21

-Venous blood from the entire GI tract and spleen drains into hepatic portal vein and provides 80% of blood flow to the liver

Question 22

Describe the course of esophagus into the abdominal cavity.

Answer 22

Esophagus courses within the posterior mediastinum to enter abdominal cavity via esophageal hiatus (T10); esophageal hiatus functions as inferior esophageal sphincter that contracts and relaxes –> prevents reflex of gastric contents into the esophagus

Question 23

Where does the esophagogastric junction lie and what is the Z-line?

Answer 23

• esophagogastric junction: lies to the left of T11 vertebrae
• Z-line: jagged line where the mucosa abruptly changes from esophageal to the gastric mucosa

Question 24

What is a hiatal hernia? What are the two types of hiatal hernia?

Answer 24

•hiatal hernia: protrusion of part of the stomach into the mediastinum through esophageal hiatus of the diaphragm

-may occur due to weakening of muscular part of the diaphragm and widening of esophageal hiatus (inferior esophageal sphincter)
o 2 types of hiatal hernia:

1. Paraesophageal hiatal hernia: cardia remains in normal position but pouch of peritoneum including the fundus of the stomach extends through esophageal hiatus anterior to the esophagus ; there is no regurgitation of gastric contents because cardiac orifice is in normal position
2. Sliding hiatal hernia: abdominal part of esophagus, the cardia, and parts of the fundus of the stomach slide superiorly through the esophageal hiatus into the thorax especially when the person lies down or bend over; there is some regurgitation of the stomach contents into the esophagus

Question 25

What is a congenital hiatal hernia?

Answer 25

-when esophagus fails to lengthen so stomach gets pulled up through esophageal hiatus through the diaphragm

Question 26

What is pyrosis?

Answer 26

•pyrosis: aka heartburn: burning sensation in abdominal part of esophagus due to regurgitation of small amounts of food and gastric fluid into lower esophagus (GERD) -pyrosis may also indicate hiatal hernia

Question 27

What's the arterial supply of the abdominal esophagus?

Answer 27

- left gastric artery supplies the abdominal part of esophagus - abdominal aorta --> celiac trunk --> left gastric artery

Question 28

What veins drains blood from the abdominal part of the esophagus?

Answer 28

-left gastric vein drains blood from the abdominal part of esophagus into hepatic portal vein -tributaries of the left gastric vein anastomose with esophageal tributaries of the azygos vein • azygos vein empties into SVC • left gastric vein empties into hepatic portal vein • anastomoses of tributaries of the left gastric vein and azygos vein create portal-systemic anastomoses

Question 29

How do esophageal varices form and why are they life-threatening?

Answer 29

esophageal varices: • seen in portal hypertension (abnormally increased blood pressure in the portal system) and blood can’t enter liver via hepatic portal vein so causes a reversal flow into esophageal tributary due to portal-systemic anastomoses → large volume of blood cause submucosal veins to enlarge → esophageal varices • distended collateral channels may rupture and cause severe hemorrhage that is life threatning • seen in patients with alcoholic cirrhosis

Question 30

Describe the pylorus of the stomach.

Answer 30

•pylorus: distal part of the stomach; sphincter region of pyloric part • has circular layer of smooth muscle that controls discharge of the stomach contents through pyloric orifice into the duodenum • stomach emptied due to: 1. Intragastric pressure overcomes the resistance of pylorus 2. At irregular intervals, gastric peristalsis pushes chyme through pyloric canal and orifice into small intestine for further mixing, digestion, absorption

Question 31

How is Helicobacter pylori infection related to gastric ulcers and why are ulcers that perforate through the posterior wall of the stomach life-threatening?

Answer 31

-Gastric ulcers: open lesions of the mucosa of the stomach -Peptic ulcers: lesions of the mucosa of pyloric canal and duodenum o The high acid in stomach and duodenum overwhelms the bicarbonate produced by duodenum and reduces the effectiveness of mucous lining, leaving it vulnerable to H. pylori o H. pylori: erodes the mucous lining of the stomach and make it vulnerable to gastric acid and enzymes and if it erodes the gastric arteries → cause life-threatning bleeding o Posterior gastric ulcer: may erode through the stomach wall into the pancreas → causing referred pain to the back • May cause erosion of the splecnic artery → severe hemorrhage into peritoneal cavity

Question 32

What are the intraperitoneal foregut derivatives?

Answer 32

-superior part of duodenum and proximal portion of the descending part of duodenum

Question 33

What are the retroperitoneal midgut derivatives?

Answer 33

-distal portion of descending part of duodenum, horizontal part of duodenum, ascending part of duodenum

Question 34

What is the anterior and posterior surface of the 1st, 2nd, and 3rd part of the duodenum?

Answer 34

1st part: superior part of duodenum: A: liver and gallbladder P: gastroduodenal artery 2nd part: descending part of duodenum A: transverse colon P: right kidney 3rd part: horizontal part of duodenum: A: superior mesenteric artery P: aorta

Question 35

What is the arterial supply and venous drainage of the foregut-derived duodenum?

Answer 35

- foregut derived duodenum: superior part of duodenum and proximal portion of the descending duodenum - superior and inferior pancreaticoduodenal artery supplies the duodenum - venous blood from duodenum drains into hepatic portal vein

Question 36

When do duodenal ulcers cause peritonitis, which organs can become inflamed, and why can life-threatening hemorrhage occur?

Answer 36

oInflammatory erosions of duodenal mucosa oMost occur in the posterior wall of the superior part of the duodenum oPeritonitis: when ulcer perforates the duodenal wall permitting contents to enter peritoneal cavity • Superior part of duodenum closely relates to liver, gallbladder, and pancreas: may adhere to the inflamed duodenum o erosion of gastroduodenal artery: results in severe hemorrhage into peritoneal cavity → leads to peritonitis

Question 37

Describe lymph drainage from the foregut derivatives

Answer 37

-celiac lymph nodes surround the celiac trunk

Question 38

Describe the sympathetic innervation of foregut derivatives.

Answer 38

-presynaptic greater splanchnic nerves (T5-T9) pass through the paravertebral sympathetic ganglia and synapse with the pre vertebral celiac ganglion; postsynaptic sympathetic fibers form celiac ganglion form periarterial plexus on branches of celiac trunk to innervate foregut-derived viscera (esophagus, stomach, proximal duodenum, gallbladder, liver, pancreas)

Question 39

Describe the parasympathetic innvervation of foregut derivatives.

Answer 39

-vagus nerve contributes branches to the peri-arterial plexus

Question 40

Describe the route of visceral afferent fibers. Describe visceral pain.

Answer 40

- visceral afferent fibers from DRG at T5-T9 go through the white communicating rami and join the presynaptic fibers of great splanchnic nerves enroute to celiac ganglion - visceral afferent fibers convey pain sensations from foregut derivatives to DRG at T5-T9 and from there both visceral pain and somatic pain fibers are relayed together by DRG at T5-T9 to CNS - visceral pain in CNS: from foregut-derivateivs is perceived as dull, diffuse pain sensations in the epigastric region of anterior abdominal wall

Question 41

How is somatic pain perceived?

Answer 41

- DRG also receives pain sensations from somatic sensory fibers of spinal nerves T5-T9 - somatic pain originates: at regional parietal peritoneum of epigastric region or from cutaneous sensory fibers of epigastric region - in the CNS, somatic pain is perceived as sharp, localized pain

Question 42

What constitutes the periarterial plexus?

Answer 42

- postsynaptic sympathetic fibers from greater splanchnic nerved T5-T9 - visceral afferent fibers - presynaptic vagus nerve

Question 43

Why is visceral pain from duodenal or gastric ulcers consciously perceived in the epigastric region?

Answer 43

Visceral pain from duodenal or gastric ulcers perceived in epigastric region because somatic pain from regional parietal peritoneum or cutaneous sensory fibers of epigastric region is relayed to CNS with visceral pain from the foregut derivatives

Question 44

Where is the spleen located?

Answer 44

- spleen: largest lympathic organ - it is positioned posteriorly in the left upper quadrant - protected by the left 9th-12th ribs - left kidney is posteroinferior to spleen - spenic hilum: adjacent to tail of pancreas

Question 45

Why is the spleen the most frequently injured abdominal organ?

Answer 45

- spleen is the most frequently injured abdominal organ in the abdomen even though its protected by the 9th-12th ribs but those ribs can be detrimental because severe blows on the left side may fracture one or more of these ribs that may lacerate the spleen - in addition, blunt trauma to abdomen → increases intra-abdominal pressure → can cause the thin fibrous capsule and overlying peritoneum of spleen to rupture → disturbs soft pulp - if spleen is ruptured → there is profuse bleeding → intraperitoneal hemorrhage and shock

Question 46

Describe the splenic artery.

Answer 46

Celiac trunk gives rise to splenic artery and near the hilum gives rise to: 1) left gastroepiloic artery 2) short gastric arteries which supplies the fundus of the stomach

Question 47

Describe the relationships of the splenic vein, IMV, SMV.

Answer 47

-inferior mesenteric vein empties into splecnic vein → courses posterior to pancreas and joins superior mesenteric vein at the origin of hepatic portal vein

Question 48

What is splenomegaly, and where is it palpated?

Answer 48

- splenomegaly: due to diseased spleen → due to hemolytic or granulocytic anemias in which RBCs and WBCs are respectively destroyed at abnormally high rates - it is palpated below the left costal margin at the end of inspiration