Upper GI Tract Structure And Function

Question 1

why do we chew ?

Answer 1

prolong the taste experiance

defence against respiratory failure (prevent choking)

Question 2

what is the chewing reflex ?

Answer 2

contraction of the jaw muscles cause pressure of food against the gums, hard palate and tongue

this triggers mechanoreceptors which inhibit the jaw muscles

this then reduces the pressure in the mouth

Question 3

what three glands secrete saliva ?

Answer 3

parotid, submandibular, sublingual

Question 4

what is in saliva ?

Answer 4

water - softens and moistens particles

muffins- combine with water to form mucus for lubrication

A-amylase- begins the breakdown of polysaccharides into monosaccharides

electrolytes- control the pH/tonicity

lysozyme - bactericidal to cleave polysaccharide component of cell wall and make it inviable

Question 5

what regulates movement of material into and out of the oesophagus ?

Answer 5

upper and lower oesophageal sphincters

Question 6

how much does the stomach volume increase by during swallowing ?

Answer 6

50ml-1500ml (no change in pressure)

Question 7

what are the functions of the stomach ?

Answer 7

temporary store of ingested material

dissolve food particles and begin digestion

control delivery of contents into the small intestine (pyloric sphincter)

sterilise ingested material (using HCL)

produce intrinsic factor to bind with Vitamin B12

Question 8

what extra muscle is present in the muscularis externa of the stomach ?

Answer 8

oblique muscle

Question 9

how are the mucosa and submucosa in the stomach described ?

Answer 9

rugae