Session 3

Question 1

Give a brief overview of the epithelia of the GI tract

Answer 1

Large excretory ducts – psudostratified

Anal canal & oesophagus – stratified squamous epithelium

Columnar -> gall bladder, small(villi) & large intestine, pancreas etc

Lamina propria
– Lots of lymphoid nodules and macrophages
– Produce antibodies (mainly IgA which is resistant to proteases)
• Protect against bacterial/viral invasion

Question 2

Where are goblet cells located?

How is the goblet cell specialised & how does this increase function?

Answer 2

Increasing in number from duodenum to colon

Scattered in between enterocytes

Produces mucus protects epithelia from:
– Friction (acts as lubricant)
– Chemical damage (acidic environment)
– Bacterial inflammation (forms physical barrier)

Question 3

What specialised cell is this image showing

Answer 3

Gastric surface mucous cells (foveolar cells) -> Secrete mucus/HCO3

Question 4

1. Other than villi and microvilli what other feature of the small intestine increases SA ?
2. The stomach needs to be easily expandable how is it specialised to do this?
3. State the layers the abdominal wall is made out of (mention the anterolateral muscles)
4. What is the rectus sheath?

Answer 4

1. Plicae
2. Rugae
3. • Skin
   • Fascia/fat -> Superficial & deep
   • 3x anterolateral muscles
   – External oblique – Internal oblique – Transverse abdominis – Rectus abdominis
   • Transversalis fascia
   • Peritoneum
4. The aponeurosis of the lateral muscles surrounding the rectus abdominis

Question 5

1. What is the arcuate line of the rectus sheath?

2.

3. What is a peritoneal ligament? Give two examples.
4. What͛s another definition for the peritoneal ligament? Give two examples.

Answer 5

1. – Lower limit of the posterior layer of rectus sheath

– Point at which inferior epigastric vessels pierce rectus abdominus

– Roughly half way between umbilicus and pubic crest

2.

3. A double fold of peritoneum that connects two viscera together

– Gastrocolic ligament (Stomach to transverse colon)

– Gastrosplenic ligament (Stomach to spleen)

4. a double fold of peritoneum that connects a viscera to the abdominal wall

– Falciform ligament (liver to anterior abdominal wall)

– Triangular ligaments (liver to diaphragm)

Question 6

What are omenta?

Answer 6

Folds of peritoneum

Greater omenta: Fold of visceral peritoneum that hangs down from the stomach. It extends from the greater curvature of the stomach, passing in front of the SI & doubles back to ascend to the transverse colon before reaching to the posterior abdominal wall.

Lesser omentum: Double layer of peritoneum that extends from the liver to the lesser curvature of the stomach (hepatogastric ligament) and the first part of the duodenum (hepatoduodenal ligament).

Question 7

Classify the types of sphincters along the alimentary tract and describe their function LO

1. Name all the sphincters in the alimentary tract
2. What is the purpose of sphincters?

Answer 7

1. • Upper oesophageal

• Lower oesophageal
• Pyloric sphincter
• (Oddi)
• Ileo-caecal (valve)

• Anal
– Internal
– External VOLUNTARY

2. • Divide tube into sections

• Control movement along the tube
• Prevent reflux of material

Question 8

State the branches of the AA

Question 9

1. Which vertebral level does the coeliac trunk, SMA & IMA branch.
2. The coeliac trunk extends approximately 1cm before dividing into three major branches – ?
   Provides an arterial supply to?
3. The left gastric artery is the smallest of the three branches. It ascends across the diaphragm, giving rise to ? branches, before continuing anteriorly along the ? of the stomach. Here, it anastomoses with the ?

Answer 9

1. CT - T12

SMA - L1

IMA - L3

2. • left gastric, splenic and common hepatic arteries
     - stomach, spleen, liver, gall bladder, abdominal oesophagus, pancreas & duodenum
3. oesophageal, lesser curvature, right gastric artery

Question 10

Splenic artery arises from the coeliac trunk just inferior to the left gastric artery. It then travels left towards the spleen, running posterior to the stomach and along the superior margin of the pancreas. During its course, it is contained within the splenorenal ligament. It terminates into five branches which supply the segments of the spleen. In addition to supplying the spleen, the splenic artery also gives rise to several important vessels:

Answer 10

Left gastroepiploic: supplies the greater curvature of the stomach. Anastomoses with the right gastroepiploic artery

Short gastrics: 5-7 small branches supplying the fundus of the stomach

Pancreatic branches: supply the body and tail of the pancreas

Question 11

The common hepatic artery is the sole arterial supply to the liver and the only branch of the coeliac artery to pass to the right. As it travels past the superior aspect of the duodenum, it divides into its two terminal branches –?

Answer 11

proper hepatic and gastroduodenal arteries

Question 12

The proper hepatic artery ascends through the lesser omentum towards the liver. It gives rise to:

Answer 12

Right gastric: supplies the pylorus and lesser curvature of the stomach

Right and left hepatic: divide inferior to the porta hepatis and supply their respective lobes of the liver

Cystic: branch of the right hepatic artery – supplies the gall bladder

Question 13

The gastroduodenal artery descends posterior to the superior portion of the duodenum. Its branches are:

Answer 13

A. Right gastroepiploic: supplies the greater curvature of the stomach. Found between the layers of
the greater omentum, which it also supplies.
Superior pancreaticoduodenal: divides into an anterior and posterior branch, which supplies the
head of the pancreas.

Question 14

The pancreaticoduodenal arcade is a network of arteries that surround and supply the head of the pancreas.
There are two main arteries – each has an anterior and posterior branch, that anastomose (e.g. anterior to anterior) forming a ring structure:

Answer 14

A. Superior pancreaticoduodenal– a branch of the gastroduodenal artery.

Inferior pancreaticoduodenal – branch of superior mesenteric artery (SMA).

Question 15

Branches of the SMA?

Answer 15

inferior pancreaticoduodenal artery = inferior region of the head of the pancreas, the uncinate process, and the duodenum.

Middle colic artery – supplies the transverse colon.

Right colic artery – supplies the ascending colon

jejunal = smaller number of arterial arcades, but longer vasa recta

ileocolic = more arterial arcades with shorter vasa recta = ascending colon, appendix, cecum, and ileum

Question 16

1. The IMA:

Answer 16

1. Left colic artery,

sigmoid artery

superior rectal artery - crosses the left common iliac artery & vein

Question 17

1. What is the Marginal artery (of Drummond) – ?
   (2. Arc of Riolan – anastomosis between the middle colic branch of SMA and the left colic branch of IMA. It is less common than the marginal artery, and indeed its existence has been questioned by some surgeons.)
2. The splenic flexure can be described as a watershed area, what does this mean?

Answer 17

1. • inner border of the colon
     - vasa recta arise from the artery
     - Formed by anastomoses between:

Ileocolic, right & middle colic of the SMA,

left colic & sigmoid branches of the IMA

3. • dual blood supply from the most distal branches of two large arteries
     - more resistant to ischaemia if one of the arteries becomes occluded
     - more sensitive to systemic hypoperfusion

Question 18

Portal vein is formed by ?

Location?

Answer 18

splenic & superior mesenteric vein

posterior to the neck of the pancreas, L2

Ascends: posteriorly to the superior part of the duodenum & bile duct

portal vein divides into right & left branches

Question 19

The portal vein is formed by the union of the splenic vein and superior mesenteric vein. It receives additional tributaries from:

Answer 19

Right and left gastric veins – drain the stomach

Cystic veins – drains the gallbladder

Para-umbilical veins – drain the skin of the umbilical region

Question 20

1. The portal vein is formed by the union of the splenic vein and superior mesenteric vein. It receives additional tributaries from:
2. Unlike the splenic artery, the splenic vein is straight and it maintains contact with the ? As it reaches the neck of the pancreas, the splenic vein joins the ? to form the ?
3. Tributaries to the splenic vein include:
4. The inferior mesenteric vein drains blood from the ? It begins as the ? vein and ascends, receiving tributaries from the ? As it ascends further it passes posteriorly to the body of the pancreas and typically joins the splenic vein.

Answer 20

1. Right and left gastric veins – drain the stomach

Cystic veins – drains the gallbladder

Para-umbilical veins – drain the skin of the umbilical region

2. Body of the pancreas as it crosses the posterior abdominal wall, superior mesenteric vein, portal vein
3. Short gastric veins – drain the fundus of the stomach.

Left gastro-omental vein – drains the greater curvature of the stomach.

Pancreatic veins – drain the pancreas.

Inferior mesenteric vein – drains the colon.

A.- rectum, sigmoid colon, descending colon and splenic flexure

• superior rectal
• sigmoid veins and the left colic veins