Intro to GI tract

Question 1

What are the terms used to describe the GI tract?

Answer 1

gut, alimentary canal, digestive tract

Question 2

What is the typical length of the GI tract?

Answer 2

up to 10m

Question 3

In which body cavities are the oesophagus and other digestive organs located?

Answer 3

oesophagus in thoracic cavity; other digestive organs in abdominal cavity

Question 4

What are the four layers of the GI tract wall?

Answer 4

• Mucosa
• Submucosa
• Muscularis
• Serosa

Question 5

What is the mucosa?

Answer 5

the lining of the GI tract, comprising three layers including a thin layer of muscle

Question 6

What is the function of the submucosa?

Answer 6

connective tissue where blood vessels and nerves lie

Question 7

What is the muscularis layer composed of?

Answer 7

layers of smooth muscle and enteric nervous system

Question 8

What is the serosa?

Answer 8

the visceral layer of the peritoneum

Question 9

What is the primary function of the mouth?

Answer 9

mastication, speech, start digestion, some absorption

Question 10

What are the components of the mouth?

Answer 10

• lips
• cheeks
• soft and hard palates
• tongue
• salivary glands
• teeth

Question 11

What are the three divisions of the pharynx?

Answer 11

• Nasopharynx
• Oropharynx
• Laryngopharynx

Question 12

What is peristalsis?

Answer 12

the movement of a food bolus from the buccal cavity to the oesophagus

Question 13

What is the length of the oesophagus?

Answer 13

about 25cms long

Question 14

What type of epithelium lines the oesophagus?

Answer 14

stratified squamous epithelium until the last 1cm, where it transitions to columnar epithelium

Question 15

What are the characteristics of the muscles in the oesophagus?

Answer 15

voluntary (striated) in upper third; involuntary (smooth) in lower third; mixed in middle

Question 16

What is the function of the upper oesophageal sphincter?

Answer 16

stops air getting into the gut

Question 17

What is the role of the lower oesophageal sphincter?

Answer 17

prevents acid/food reflux

Question 18

What is the variable capacity of the stomach?

Answer 18

can hold up to 1.5L, usually collapsed

Question 19

What are the parts of the stomach?

Answer 19

• cardia
• fundus
• body
• antrum

Question 20

What is the mucosa of the stomach adapted into?

Answer 20

folded into rugae with gastric pits

Question 21

What do chief cells in the stomach secrete?

Answer 21

enzymes of gastric juice (pepsin)

Question 22

What is the function of parietal cells?

Answer 22

secrete hydrochloric acid and intrinsic factor

Question 23

What hormones do endocrine cells in the stomach secrete?

Answer 23

• ghrelin (promotes appetite)
• gastrin (digestive hormone)

Question 24

What is the primary function of the stomach?

Answer 24

• food reservoir
• digestion
• secretes intrinsic factor
• some absorption

Question 25

What is the length and diameter of the small intestine?

Answer 25

approx 6-8m long and 2.5cms wide

Question 26

What are the three divisions of the small intestine?

Answer 26

* Duodenum * Jejunum * Ileum

Question 27

What is the length of the duodenum?

Answer 27

25cms long

Question 28

What transitions the duodenum into the jejunum?

Answer 28

DJ flexure

Question 29

What is the function of the mucosa in the small intestine?

Answer 29

folded into villi to increase surface area for absorption

Question 30

What do enterocytes in the small intestine have?

Answer 30

microvilli, known as the 'brush border'

Question 31

What are the sections of the large intestine?

Answer 31

* Caecum * Colon (ascending, transverse, descending, sigmoid) * Rectum * Anal canal

Question 32

What is the function of the rectum?

Answer 32

repository for stool, ends at the anal canal

Question 33

What are the two types of anal sphincters?

Answer 33

* internal (smooth muscle) * external (striated muscle)

Question 34

What is the length of the appendix?

Answer 34

8-10cms long

Question 35

What is the peritoneum?

Answer 35

a continuous membrane that covers most abdominal organs

Question 36

What are the two layers of the peritoneum?

Answer 36

* Visceral * Parietal

Question 37

What does 'intraperitoneal' mean?

Answer 37

lies within the peritoneum

Question 38

What does 'retroperitoneal' refer to?

Answer 38

extraperitoneal and behind the peritoneum

Question 39

What is the function of the mesentery?

Answer 39

attached to the small intestine and prevents it from knotting up, also provides blood supply

Question 40

What is the function of the omentum?

Answer 40

hangs over the intestines and can seal off perforations/inflammation

Question 41

What are the main functions of the gallbladder?

Answer 41

* Stores bile * Empties when triggered by gut hormone (CCK)

Question 42

What is the length of the pancreas?

Answer 42

15cm long

Question 43

What is the major function of the exocrine pancreas?

Answer 43

secrete pancreatic juice, including digestive enzymes and sodium bicarbonate

Question 44

What are the islets of Langerhans?

Answer 44

islands of endocrine cells in the pancreas that secrete hormones

Question 45

What are the most important hormones secreted by the pancreas?

Answer 45

* insulin (from beta cells) * glucagon (from alpha cells)

Question 46

What is important to appreciate in understanding pathology?

Answer 46

normal structure of the GI tract