digestion and absorption

Question 1

4 main subdivisions of digestive tract

Answer 1

oesophagus, stomach, small and large intestines

Question 2

digestion and absorption of carbohydrates and amino acids?

Answer 2

digestion of carb in oral cavity (amylase)

• most digestion and absorption of carb and amino acids across mucosal of stomach and small intestine.
• secretions from pancreas (HCO3) and liver (bile salts) pass into lumen of small intestine

Question 3

absorption of fat

Answer 3

lymph vessels distributed through tract and involved in absorption

Question 4

4 concentric muscle layers making up GI tract (from lumen outward)

Answer 4

mucosa
submucosa
muscilaris and adventitia of the serosa

Question 5

describe mucosa

Answer 5

• superficial epithelium
• underlying storm with loose, vascular connective tissue which is rich in immunocompetent cells (lamina propriety)
• thin smooth muscle later (muscular mucosae)
• inner circular and outer longitudinal

Question 6

describe submucosa

Answer 6

large blood vessels

• lymph vessels
• nerves send fibres to mucosa and muscular layers = messner’s plexus

Question 7

describe muscularis externa

Answer 7

2 muscle layers:

• smooth (except upper esophagus and anal sphincter - striated muscle).
• inner circular laters surrounded by outer longitudinal
• circular constrict lumen, longitudinale shortens tube
• circular later thickened at sphincter points

Question 8

describe adventitia or serosa

Answer 8

layers of connective tissue, alternately collagenous and elastic
-covered by thin later of mesothelial cells