Digestive System 1 - Introduction

Question 1

Name the two main parts of the digestive system?

Answer 1

Alimentary canal (aka gastrointestinal or GI tract)
Accessory digestive organs

Question 2

What organs are found in the gastrointestinal (GI) tract?

Answer 2

–> Oral cavity
–> Pharynx
–> Oesophagus
–> Stomach
–> Small intestine (made of the duodenum, jejunum and ileum)
–> Large intestine (made of the caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal).

Question 3

What organs are found in the accessory digestive organs?

Answer 3

Teeth
Tongue
Salivary glands
Liver
Gallbladder
Pancreas

Question 4

What is the function of the GI tract and accessory digestive organs?

Answer 4

GI tract:
A continuous tube through which ingested materials is propelled.

Accessory digestive organs:
Assists in the digestion of ingested materials.

Question 5

What is the primary germ layer that the digestive system is derived from?

Answer 5

The endoderm (with a small contribution from the mesoderm).

Question 6

Briefly describe the embryological development of the digestive system?

Answer 6

1. At the end of the 3rd week: The folding of the embryo transforms the endoderm and the most lateral parts of the mesoderm into a primitive gut tube.
2. This tube eventually connects to the mouth and the anus.
3. A double-layered membrane called the dorsal mesentery helps to anchor the gut tube to the posterior body wall.
4. A portion of the gut tube is also attached to the anterior body wall by a membrane called the ventral mesentery.

Question 7

Name the digestive organs that are derived from the foregut?

Answer 7

GI tract organs:
Stomach
First part of the duodenum (part of the small intestine)

Accessory digestive organs:
Liver
Gallbladder
Pancreas

Question 8

Name the digestive organs that are derived from the midgut?

Answer 8

GI tract organs:
Most of the duodenum (part of the small intestine)
Jejunum (part of the small intestine)
Ileum (part of the small intestine)
Caecum (part of the large intestine)
Ascenging colon (part of the large intestine)
Proximinal 2/3 of the transverse colon (part of the large intestine)

Question 9

Name the digestive organs that are derived from the hindgut?

Answer 9

GI tract organs:
Distal 1/3 of the transverse colon (part of the large intestine)
Descending colon (part of the large intestine)
Sigmoid colon (part of the large intestine)
Rectum (part of the large intestine)
Superior part of the anal canal (part of the large intestine)

Question 10

What is the peritoneum?

Answer 10

The serous membrane lining the abdominopelvic cavity.

Question 11

What are the 3 layers of the peritoneum?

Answer 11

Outer parietal peritoneum
Inner visceral peritoneum
Peritoneal cavity

Question 12

Describe the different layers of the peritoneum?

Answer 12

Outer parietal peritoneum:
Lines the walls of the abdominopelvic cavity.

Inner visceral peritoneum:
Lines the surface of the organs within the abdominopelvic cavity.

Peritoneal cavity:
The thin serous peritoneal fluid in this cavity reduces friction during movement of the abdominopelvic organs.

Question 13

What are the 2 spaces that the peritoneal cavity can be divided into?

Answer 13

Greater sac
Lesser sac

Question 14

Identify the main folds of the peritoneum?

Answer 14

Question 15

Where do the greater & lesser omentum develop from?

Answer 15

Greater omentum:
It develops from the dorsal mesentery of the primitive gut tube.

Lesser omentum:
It develops from the ventral mesentery of the primitive gut tube.

Question 16

Describe the location of the main folds of the peritoneum?

Answer 16

Greater omentum:
Extends from the greater curvature of the stomach & drapes over most of the abdominal organs.

Lesser omentum:
Extends from the lesser curvature of the stomach and the duodenum to the liver.

Mesocolon:
Suspends parts of the large intestine from the posterior abdominal wall.

Mesentery proper:
Suspends most of the small intestine from the posterior abdominal wall.

Question 17

Define intraperitoneal and retroperitoneal?

Answer 17

Intraperitoneal:
Organs that are completely surrounded by visceral peritoneum.

Retroperitoneal:
Organs that are only covered by parietal peritoneum on their anterior surfaces.

Question 18

Name the digestive organs that are intraperitoneal?

Answer 18

Stomach
First part of the duodenum (part of the small intestine)
Jejunum (part of the small intestine)
Ileum (part of the small intestine)
Caecum (part of the large intestine
Transverse colon (part of the large intestine)
Sigmoid colon (part of the large intestine)
Liver (except for a small area)
Gallbladder
Tail of the pancreas

Question 19

Name the digestive organs that are retroperitoneal?

Answer 19

Oesophagus
Most of the duodenum (part of the small intestine)
Most of the pancreas
Ascending colon (part of the large intestine)
Descending colon (part of the large intestine)
Rectum (part of the large intestine)

Question 20

List the basic functions of the digestive system?

Answer 20

Ingestion
Motility
Secretion
Digestion
Absorption
Elimination of wastes

Question 21

Describe the basic functions (ingestion, motility, secretion) of the digestive system?

Answer 21

Ingestion:
The first step in the process of digesting and absorbing nutrients.

Motility:
The movement of ingested material through the GI tract, which involves peristalsis and mixing.

Secretion:
The process of producing and releasing substances such as mucous, acid, bile and digestive enzymes into the lumen of the GI tract.

Question 22

Describe the basic functions (digestion, absorption and elimination of wastes) of the digestive system?

Answer 22

Digestion:
This is the breaking down of ingested material into smaller, usable components through both mechanical and chemical digestion.

Absorption:
This is the passage of nutrients, vitamins, electrolytes and water into the blood and lymphatic vessels within the wall of the GI tract.

Elimination of wastes:
This is the removal of all undigestible material and waste products secreted by the digestive organs through the process of defecation.

Question 23

Fill in the table?

Answer 23