Principles - Lower GI System

Question 1

What is the lower GI tract?

Answer 1

Caecum 
Appendix 
Colon
Rectum
Anal canal 
Anus

Question 2

What is the end of the upper GI tract?

Answer 2

The ileocaecal junction

Question 3

What is the small intestine made up of?

Answer 3

The duodenum - leaves the stomach and curves round the head of the pancreas
The jejunum
The ileum - terminal part of the small intestine, connects with first part of the large intestine

Question 4

From proximal to distal, name the sections of the large intestine.

Answer 4

The colon (caecum, appendix, ascending colon, transverse colon, descending colon and sigmoid)
The rectum
The anal canal
The anus

Question 5

What are the different layers of the walls of the intestine?

Answer 5

Mucosa (innermost)
Inner circularly arranged smooth muscle
Outer longitudinally arranged smooth muscle
Visceral peritoneum

Question 6

What are mesenteries?

Answer 6

An organ’s double layer of visceral peritoneum

Question 7

What does the outer longitudinal layer of smooth muscle do in the intestine?

Answer 7

Shortens the tube during peristalsis

Question 8

What does the inner circular layer of smooth muscle do in the intestine?

Answer 8

Constricts the diameter of the tube during peristalsis

Question 9

What does the abdominal cavity contain?

Answer 9

Peritoneal cavity and retroperitoneum

Question 10

What is the retroperitoneum?

Answer 10

The space within the abdominal cavity posterior to the peritoneum

Question 11

How do the abdominal organs fit into the abdominal cavity?

Answer 11

By pushing into the peritoneal cavity - they never enter the cavity, they just push into it

Question 12

What is the peritoneum?

Answer 12

The serous membrane that forms the lining of the abdominal cavity

Question 13

What is visceral peritoneum?

Answer 13

The peritoneum that touches the organs

Question 14

What is parietal peritoneum?

Answer 14

the peritoneum that lines the abdominal and pelvic cavities

Question 15

What is an intraperitoneal organ? Give an example.

Answer 15

An organ almost completely covered with visceral peritoneum - minimally mobile as it has been anchored by the peritoneum
e.g. liver

Question 16

What is a retroperitoneal organ? Give an example.

Answer 16

Located in the retroperitoneum - visceral peritoneum only on its anterior surface
e.g. pancreas and kidneys

Question 17

What is an organ with mesentery?

Answer 17

An organ covered in visceral peritoneum and suspended from the posterior abdominal wall by a mesentery - organ is highly mobile
e.g. parts of the intestines

Question 18

What are the organs of the foregut?

Answer 18

Oesophagus to mid-duodenum
Liver
Gallbladder
Spleen
Half the pancreas

Question 19

What are the organs of the midgut?

Answer 19

Mid-duodenum to proximal 2/3rds of the transverse colon

half of the pancreas

Question 20

What are the organs of the hind gut?

Answer 20

Distal 1/3rd of the transverse colon to proximal 1/2 of the anal canal

Question 21

What are the 3 midline branches of the abdominal aorta?

Answer 21

1. coeliac trunk - foregut organs
2. superior mesenteric artery - midgut organs
3. inferior mesenteric artery - hindgut organs

Question 22

Where do branches of the superior mesenteric artery go?

Answer 22

Into the mesentery of the small intestine

Question 23

Where do branches of the inferior mesenteric artery go?

Answer 23

Into the mesentery of the sigmoid colon

Question 24

What does the inferior vena cava drain?

Answer 24

The cleaned blood from the hepatic veins into the right atrium

Question 25

What does the hepatic portal vein do?

Answer 25

Drains the blood from the foregut, midgut and handgun structures to the liver for first pass metabolism

Question 26

What does the splenic vein do?

Answer 26

Drains the blood from the foregut structures into the hepatic portal vein

Question 27

What does the inferior mesenteric vein do?

Answer 27

Drains blood from the hindgut structures to the splenic vein

Question 28

What does the superior mesenteric vein do?

Answer 28

Drains the blood from the midgut structures to the hepatic portal vein.

Question 29

What is the portal venous system?

Answer 29

This is via the hepatic portal vein
It drains blood from the absorptive parts of the GI tract and the associated organs of the GI tract to the liver for first pass metabolism

Question 30

What are the two venous systems present in the GI tract? Where do they meet?

Answer 30

Portal venous system
Systemic venous system

Meet in the liver - hepatic portal vein carries venous blood from the portal venous system to the liver
The liver then passes the blood int the IVC via the hepatic veins to return to the heart

Question 31

What is the systemic venous system?

Answer 31

IVC and SVC
Drains deoxygenated blood from the rest of the body to the right atrium of the heart, including blood draining from the liver via the hepatic veins

Question 32

What is the blood supply of the liver?

Answer 32

Hepatic artery and hepatic portal vein

Question 33

Where do foregut structures drain their lymph?

Answer 33

via nodes located along the splenic artery towards the coeliac nodes

Question 34

Where do midgut structures drain their lymph?

Answer 34

Via nodes located along the superior mesenteric artery towards the superior mesenteric nodes

Question 35

Where do hindgut structures drain their lymph?

Answer 35

Via nodes located along the inferior mesenteric artery towards the inferior mesenteric nodes

Question 36

Where is the pyloric sphincter? Is it smooth or skeletal muscle?

Answer 36

in-between stomach and duodenum

smooth muscle

Question 37

What are anatomical sphincters?

Answer 37

Discrete areas where muscle completely encircles the lumen of the tract - can be smooth muscle or skeletal muscle

Question 38

Where is the cricopharyngeal sphincter?

Answer 38

at the junction between laryngopharynx and oesophagus

Question 39

Where is the external anal sphincter?

Answer 39

At the junction between anus and external environment