3. Anatomy, Histology and Control of GI Tract

Question 1

Which organs compose the alimentary canal?

Answer 1

Mouth - Pharynx - Oesophagus - Stomach - Small Intestine - Large Intestine

Question 2

Where does the alimentary canal terminate?

Answer 2

Anus

Question 3

Outline the accessory digestive organs

Answer 3

Teeth - Tongue - Gall Bladder - Salivary Glands - Liver - Pancreas

Question 4

What colour does glandular mucosa stain and why?

Answer 4

Dark purple - epithelial and connective tissue nuclei within

Question 5

What marks the muscularis mucosa?

Answer 5

Thin strip

Question 6

What is the submucosa composed of?

Answer 6

Mainly dense collagen fibres

Question 7

How many muscularis externa layers are present?

Answer 7

2. Wide inner band of circular SMC and narrow outer band of longitudinal SMC

Question 8

What can trigger changes in GI tract functions other than local stimuli?

Answer 8

CNS signals - anticipation of food

Question 9

What local stimuli can trigger changes in function of GI Tract?

Answer 9

Concentration of specific nutrients

Osmolarity

pH

Distension

Stimulation leads to action on sensory receptors in mucosal layer of tract to initiate reflexes

Question 10

Elaborate on nervous control of the GI tract

Answer 10

Extrinsic: autonomic nerves of CNS via parasympathetic vagus nerve

Stimulates blood flow, motility, secretion, relaxes sphincters

Sympathetic nerves do the opposite

Question 11

What cell aids the production of gastric acid via release of histamine?

Answer 11

Enterochromaffin-like cells which are scattered through the mucosal layer