Lecture 9 - Pancreas and the small intestine

Question 1

The pancreas: what is it, what is it located between, and what are its relations?

Answer 1

Exocrine and endocrine organ

Lies between the duodenum and spleen

Relations of the pancreas:
* Retroperitoneal
* Located in the epigastrium and left hypochondrium
* Lies transversely across the posterior abdominal wall
* Is posterior to the stomach

Question 2

The pancreas: the regions

Answer 2

Tail - leftmost part, near the spleen
Body - between tail and neck
Neck - right next to aorta and IVC
Head - touching the duodenum
Uncinate process - bottom part of the pancreas, where the blood connects

Question 3

Pancreatic exocrine functions

Answer 3

Tubuloacinar glands containing pyramid-shaped acinar cells that secrete digestive enzymes as pancreatic juice which is secreted into the duodenum via intralobular and then pancreatic ducts

Question 4

Pancreatic ducts

Answer 4

Main pancreatic duct:
* Accessory pancreatic duct - minor duodenal papilla
* Hepatopancreatic ampulla - Major dupodenal papilla

Sphincters - sphincters are found at the beginning of the MDP and the HA/BD joining to the MDP

Question 5

Pancreatic endocrine functions

Answer 5

Contain Islets of Langerhans which secrete:
* Glucagon into the blood - using α cells
* Insulin into the blood - using β cells
* Somatostatin into the blood - using δ cells
* cholecystokinin
* and secretin

Question 6

Glucagon: what does it do and what secretes it?

Answer 6

Promotes the conversion of glycogen into glucose to raise blood glucose levels

α cells in the Islets of Langerhans

Question 7

Insulin: what does it do and what secretes it?

Answer 7

Promotes the conversion of glucose into glycogen to lower blood glucose levels

β cells in the Islets of Langerhans

Question 8

Insulin: what does it do and what secretes it?

Answer 8

Also known as the growth hormone inhibiting hormone, inhibits the release of other pancreatic hormones

δ cells in the Islets of Langerhans

Question 9

Cholecystokinin: what does it do and what secretes it?

Answer 9

Stimulates the secretion of digestive enzyme

I-cells of the upper small intestine in response to fat, protein, and some nonnutrients

Question 10

Secretin: what does it do and what secretes it?

Answer 10

Stimulates the secretion of bicarbonate-rich pancreatic fluid

S cells in the duodenum

Question 11

Pancreatic blood supply: how are the neck, body, and tail supplied, how is the head supplied, how is the uncinate process supplied, and what anastomosis occurs?

Answer 11

Coeliac trunk, splenic artery - subdivides into the greater pancreatic artery: supplies the neck, body, and tail of the pancreas

Coeliac trunk, gastroduodenal artery - subdivides into the anterior/posterior superior pancreaticoduodenal artery which supplies the head of the pancreas

Superior mesenteric artery - branches into the anterior/posterior inferior pancreaticoduodenal arteries which supply the uncinate process

Superior mesenteric artery and coeliac artery anastomose through the connection between the anterior/posterior inferior pancreaticoduodenal and anterior/posterior superior pancreaticoduodenal arteries

Question 12

Pancreatic venous drainage: how are the neck, body, and tail drained, how is the head drained, how is the uncinate process drained, and what is the final drainage?

Answer 12

Pancreatic veins take blood from the neck, body, and tail, and drain into the splenic vein

The superior pancreaticoduodenal vein takes blood from the head and drains blood into the superior mesenteric vein

The inferior pancreaticoduodenal vein takes blood from the uncinate process and drains blood into the superior mesenteric vein

The IMV drains into the splenic vein and drains into the hepatic portal vein, the SMV also drains into the hepatic portal vein

Question 13

Pancreatic innervation

Answer 13

Sympathetic:
* Abdominopelvic splanchnic nerves
* sympathetic chain

Parasympathetic:
* Vagus nerve

Plexuses:
* Coeliac plexus
* Superior mesenteric plexus

Question 14

Pancreas: lymphatic drainage

Answer 14

Pancreaticosplenic nodes or pyloric nodes → superior mesenteric nodes or coeliac nodes → Chysterna chyli and thoracic duct

Question 15

The duodenum: peritoneum, location

Answer 15

Mostly retroperitoneal but contains intraperitoneal parts in the superior part

The descending part in the foregut and the horizontal and ascending parts in the midgut

Question 16

Duodenum blood supply

Answer 16

Coeliac trunk, gastroduodenal artery - subdivides into the anterior/posterior superior pancreaticoduodenal artery which supplies the superior parts of the duodenum

Superior mesenteric artery - branches into the anterior/posterior inferior pancreaticoduodenal arteries which supply the duodenum

Superior mesenteric artery and coeliac artery anastomose through the connection between the anterior/posterior inferior pancreaticoduodenal and anterior/posterior superior pancreaticoduodenal arteries

Question 17

Duodenum venous drainage

Answer 17

The superior pancreaticoduodenal vein takes blood from the duodenum and drains blood into the superior mesenteric vein

The inferior pancreaticoduodenal vein takes blood from the duodenum and drains blood into the superior mesenteric vein

SMV drains into the hepatic vein - liver filtration occurs

Question 18

Duodenum histology: what are the cells, and what is special with the mucosa and the submucosa?

Answer 18

Simple columnar epithelium with goblet cells - produce mucus, trap bacteria, and have a lubricating factor

Mucosa layer - contains villi/microvilli (increase SA:V)

Submucosa - contains Brunner’s glands (secrete a thin, watery, alkaline mucus to counteract the acids entering the duodenum)

Question 19

11.19/ 19/30

Answer 19

29:30

Question 20

Jejunum and Ileum

Question 21

Mesenteries: what are they and what examples of free mesenteries are there?

Answer 21

A double fold of peritoneum that attaches part of the intestines to the posterior abdominal wall

• Mesoappendix
• The mesentery
• Transverse mesocolon
• Sigmoid mesocolon

Question 22

The mesentery: what does it do and where is it found?

Answer 22

The root of the mesentery allows entry and exit
of blood and lymph vessels, and nerves

?? watch leccy/google

Question 23

Jejunum and ileum blood supply

Answer 23

Arterial supply:
Superior mesenteric artery -> jejunal arteries, arterial arcades, ileal arteries, vasa recta, Ileocolic arteries, ileal branch

Venous drainage:
jejunal veins, venous arcades, ileal veins, vasa recta (??), Ileocolic veins, ileal branch(???) (???) -> superior mesenteric vein -> portal system

Question 24

??? innervation

Answer 24

Parasympathetic:
* posterior vagal trunks

Sympathetic:
* T8 to T10 then abdominopelvic splanchnic nerves then superior mesenteric ganglion

Visceral afferent:
* T8 to T10

Question 25

11.24

Question 26

Jejunum histology

Answer 26

• Simple columnar epithelium with goblet cells
• Plicae circulares
• Each villus has a core of lamina propria
• Few Peyer’s patches

Question 27

Ileum histology

Answer 27

11.26

• Many Peyer’s patches
• Villi/Mucosa as the outer layer
• Peyer’s patches below the surface
• Plica circulares - stick-shaped projections that the outer layer covers
• Muscularis mucosa - separates the mucosa and submucosa/plica circulares
• Submocsa - layer underneath the muscularis mucosa
• Circular muscle
• Longitudinal muscle

Question 28

Villus: what are they, what do they do, how are they supplied/innervated, and what other key features are they involved with?

Answer 28

Projections within the GI tract composed of simple columnar epithelium

Used in food absorption, carries nutrients into the hepatic portal circulation

Lamina propria - contains an extensive capillary network

• Lacteals - transport lipids into the lymphatic system
• Microvilli - cover villi surfaces to increase SA:V for absorption

Question 29

Lymphatic drainage

Answer 29

• Ileocolic lymph nodes (ileum/lower LI (?))
• Juxta-intestinal lymph nodes (J/L?) -> mesenteric lymph nodes (J)
• ILN/MLN -> superior central lymph nodes (?) -> superior mesenteric lymph nodes -> intestinal lymphatic trunk -> coeliac trunk

Check this is right tho