1 Introduction

Question 1

Q: Give 2 alternative names for the digestive system. What are the 2 main roles?

Answer 1

A: gastrointestinal, alimentary

• digestion= process of breaking down macromolecules to allow absorption
• absorption= process of moving nutrients and water across a membrane into blood and then into body

Question 2

Q: What are the components of the GI tract? (15)

Answer 2

A: parotid gland

• sublingual gland
• sub mandibular gland
• oesophagus
• stomach
• liver
• gal bladder
• pancreas
• jejenum
• duodenum
• ileum
• appendix
• colon
• rectum
• anus

Question 3

Q: Why is the GI tract considered an external environment?

Answer 3

A: it can all be accessed through sphincters, without crossing a membrane. For example, it is feasible (albeit impractical and ridiculous) to pass a single piece of string from the mouth to the anus

Question 4

Q: Describe the basic plan of the gut.

Answer 4

A: The gut lumen: the hollow tube that food and fluids pass through
The mucosa: 
The submucosa:
Smooth muscle layers: 
Serosa:

Question 5

Q: What does the mucosa include? (3) What can it also include? Result?

Answer 5

A: -lining epithelium= varies depending on part of gut

• loose connective tissue = lamina propria, which provides vascular support for the epithelium, and often contains mucosal glands.
• muscalaris mucosae

Products of digestion pass into these capillaries

Question 6

Q: What is the submucosa? What can it include? (4) What is the role of the final component?

Answer 6

A: A loose connective tissue layer

• larger blood vessels
• lymphatics
• can contain mucous secreting glands
• Includes a rich network of nerves called the submucosal plexus, which regulates secretion, absorption and local perfusion

Question 7

Q: Describe the muscle in gut walls. Made of? (2) Role?

Answer 7

A: usually two layers; the inner layer is circular, and the outer layer is longitudinal

layers of smooth muscle are used for peristalsis (rhythmic waves of contraction), to move food down through the gut

Question 8

Q: What is the serosa? AKA? difference? What covers it? What does it contain? (3)

Answer 8

A: Outermost layer of loose connective tissue
-adventitia
=> s = found around gut elements that are loose and not attached to anything. a = tends to line things that are fixed to gut wall

covered by the visceral peritoneum

• blood vessels
• lymphatic vessels
• nerves