Upper GI Tract Structure and Function

Question 1

How is chewing controlled?

Answer 1

Somatic nerves innervate skeletal muscles of mouth/jaw

Question 2

What glands secrete saliva?

Answer 2

Parotid, submandibular, sublingual

Question 3

What are the components of saliva?

Answer 3

Mucins 
Water 
Alpha amylase 
Electrolytes 
Lysozymes

Question 4

What parasympathetic nerves control salivation?

Answer 4

Cranial nerves: facial (VII) and glossopharyngeal (IX)

Question 5

How does parasympathetic stimulation effect salivation?

Answer 5

Profuse watery salivary secretions

Question 6

How does sympathetic stimulation effect salivation?

Answer 6

High mucus content

High amylase content

Question 7

What muscle type is involved in the oesophagus?

Answer 7

Upper 1/3 is skeletal muscle

Lower 2/3 is smooth muscle

Question 8

Describe the swallowing process

Answer 8

Pharyngeal muscles contract
Soft palate reflected backwards and upwards (closes off nasopharynx)
Upper oesophageal sphincter (UOS) relaxes and epiglottis covers opening to larynx

Question 9

How is bolus moved down the oesophagus?

Answer 9

Peristalsis

Question 10

What happens as the bolus nears the stomach?

Answer 10

Lower oesophageal sphincter (LOS) relaxes and bolus enters the stomach

Question 11

What are the functions of the stomach?

Answer 11

Temporary store of ingested material
Controls delivery of contents to small intestine
Produces intrinsic factor
Sterilises ingested material

Question 12

What are the 3 layers of the muscularis externa within the stomach?

Answer 12

Longitudinal (outer)
Circular (middle)
Oblique (inner)

Question 13

What are rugae?

Answer 13

Submucosa and mucosa folded when empty