GI Tract

Question 1

What is the overview of the structure GI tract?

Answer 1

• pharynx
• oesophagus
• liver
• stomach
• duodenum
• transverse colon
• ascending colon
• descending colon
• small intestine
• caecum
• appendix
• sigmoid colon
• rectum
• anus

Question 2

What is an overview of the internal GI tract from in to out?

Answer 2

MUCOSA:

• epithelium
• lamina propria
• muscular mucosa

SUBMUCOSA

• nerves
• blood vessels
• supporting connective tissue

MUSCULARIS PROPIA

• inner circular layer
• outer longitudinal layer
• third inner oblique layer (stomach only)

ADVENTITIA

Question 3

What are the types of mucosa that can be found in the GI tract?

Answer 3

• protective
• secretory
• absorptive

Question 4

Where can the protective mucosa be found?

Answer 4

• oesophagus

- anal canal

Question 5

Where can the secretory mucosa be found?

Answer 5

• stomach
• small intestine
• large intestine

Question 6

Where can the absorptive mucosa be found?

Answer 6

• small intestine

Question 7

What is special about the whole large intestine?

Answer 7

• it contains both absorptive and protective mucosa

Question 8

What kind of epithelia does protective mucosa have?

Answer 8

• stratified squamous epithelia

Question 9

What adaptations does absorptive mucosa have?

Answer 9

• microvilli which increase the surface area

Question 10

What is the oesophagus?

Answer 10

• a muscular tube that transports food from the mouth to the stomach
• it is lined by non-keratinised squamous epithelium

Question 11

How does the oesophagus move?

Answer 11

• transport is driven by peristaltic contractions

- the upper and lower oesophageal sphincter contribute to food movement control

Question 12

What type of muscle does the oesophagus contain?

Answer 12

• skeletal muscle = voluntary control at the top

- smooth muscle = involuntary control as you go further down

Question 13

Where are the mucus secreting glands within the oesophagus?

Answer 13

• within the sub-mucosa there are oesophageal glands which are mucus secreting glands
• near the stomach, oesophageal cardia glands in the lamina propria secrete mucus

Question 14

Why is the epithelium in the oesophagus so folded in?

Answer 14

• so that it can stretch when transporting food

Question 15

What is the gastric-oesophageal junction?

Answer 15

the junction between the oesophagus and the stomach mucosa, which abruptly changes from protective mucosa to glandular secretory

Question 16

What are the changes in epithelium?

Answer 16

It changes from stratified squamous epithelium in the oesophagus to simple columnar epithelium in the stomach until the anus

Question 17

What are some of the regions of the stomach?

Answer 17

• the cardia
• the fundus
• the pylorus

Question 18

What is the gastric cardia?

Answer 18

• a narrow circular band <1.5-3cm
• Mucosa contains simple or branched cardiac glands, coiled with large lumens
• Most of the glands produce mucus and lysozyme (attacks bacterial walls/breaking down pathogens)
• A few parietal cells are also found (HCl secreting)
• The glands are similar to the cardiac glands of the oesophagus

Question 19

What does the cardia contain?

Answer 19

• the cardia contains mucus secreting glands.
• The glands secrete two types of mucus and associated endocrine cells secrete gastrin.
• Glands secrete acid - pepsin as well as mucus

Question 20

What is the fundus?

Answer 20

• contains the lamina propria

- which contains gastric glands

Question 21

What are the main areas of the gastric glands?

Answer 21

• isthmus
• neck
• base