Session 2 - the Gut and the Peritoneal Cavity

Question 1

What is the peritoneum?

Answer 1

the serous membrane lining the cavity of the abdomen and covering the abdominal organs (the peritoneal/abdominal cavity)

Question 2

What is the mesothelium?

Answer 2

the epithelium that lines the pleurae, peritoneum, and pericardium

Question 3

What is the difference between the abdominal and peritoneal cavities?

Answer 3

abdominal cavity is between the abdominal wall and the peritoneum (there is nothing here)
the peritoneal cavity is within the layers of the peritoneum

Question 4

What are mesenteries?

Answer 4

periteoneal folds that attach viscera to the abdominal wall

they are conduits for vessels, nerves and lymphatics supplying viscera

Question 5

Normally, there are only 2 germ layers during embryological development. In the development of the gut tube, there are 3, what are they?

Answer 5

ectoderm
mesoderm
endoderm

After the endoderm and ectoderm have formed, interactions between the two germ layers induce the development of mesoderm. The mesoderm forms skeletal muscle, bone, connective tissue, the heart, and the urogenital system

Question 6

The gut tube is suspended from the posterior abdominal wall by a peritoneal fold. Name it

Answer 6

the dorsal mesentery

Question 7

What are the visceral and parietal peritoneum?

Answer 7

visceral - covers the suspended organs

parietal - lines the abdominal wall

Question 8

What does intraperitoneal and retroperitoneal refer to?

Answer 8

intraperitoneal - structures suspended from the abdominal wall by mesenteries. They are enclosed completely by the peritoneum
retroperitoneal - structures that lie between the parietal peritoneum and the abdominal wall

Question 9

Give an example of intraperitoneal and retroperitoneal structures

Answer 9

intra - most of the small intestine

retro - kidneys and great vessels

Question 10

How do organs become secondarily peritoneal?

Answer 10

organs originally had a mesentery, it fuses with the body wall

Question 11

Which mesenteries are there in the gut?

Answer 11

dorsal
the forgut has a ventral mesentery
NO VENTRAL MESENTERY OF THE GUT

Question 12

What is the omental bursa/lesser sac?

Answer 12

a hollow space that is formed by the greater and lesser omentum and its adjacent organs.

It communicates with the greater sac via the epiploic foramen of winslow, which is known as the general cavity of the abdomen that sits within the peritoneum, but outside the lesser sac.

Question 13

What is different about the muscle layers of the stomach compared ofthe rest of the GI tract?

Answer 13

it has 3 layers, and the rest of the GI tract has 2

Question 14

What is the pyloric sphincter and what is its role?

Answer 14

a ring of smooth muscle of the distal end of the pyloric canal that prevents food from entering the duodenum

Question 15

What is located at the first part of the duodenum?

Answer 15

duodenal cap (common location for duodenal ulcers)

Question 16

What is located at the second part of the duodenum?

Answer 16

the major duodenal papilla - entrance for the common bile duct

Question 17

What type of peritoneal structure is the duodenum?

Answer 17

retroperitoneal

Question 18

What does hepatic refer to?

Answer 18

the liver

Question 19

What are portal systemic anastomoses?

Answer 19

where veins draining the portal vein and the IVC communicate

Question 20

Describe the lymphatic drainage

Answer 20

• it follows the arterial supply

- all lymph drains into the cisterna chyli and then the thoracic duct

Question 21

What does the omental foramen connect?

Answer 21

the lesser and greater sac

Question 22

How is the greater sac divided into compartments?

Answer 22

can be divided by the dorsal mesentry at the transverse colon into two compartments
- Supracolic
- Infracolic
This is further subdivided by the dorsal mesentry of the small intestine into
- Right infracolic
- Left infracolic