upper gI tract structure and function

Question 1

How is chewing controlled

Answer 1

Voluntary - somatic nerves which innervate the skeletal muscles of the mouth and jaw

Reflex to stop the chewing - Contraction of jaw muscles  pressure of food against gums, hard palate and tongue  mechanoreceptors  inhibition of jaw muscles  reduced pressure  contraction  etc.

Question 2

What are the 3 salivary glands

Answer 2

parotid, sublingual and submandibular

Question 3

What innervates the parotid gland

Answer 3

Glossopharyngeal (CN IX)

Question 4

What innervates the sublingual and submandibular gland

Answer 4

Facial nerve (CN VII)

Question 5

What is the composition of saliva

Answer 5

99% water
Mucins - clycoprotein - mucin and water = mucous
Alpha amylase - breaks down starch and glycogen into disaccharide
Electrolyte
Lysozyme - bacteriocydal

Question 6

Why does sympathetic innervation cause a lot of mucus to be produced

Answer 6

the alpha 1 adrenorecptors innervate secretion of mucus

Question 7

What muscle the oesophagus made up of

Answer 7

upper 1/3 - skeletal muscle
Lower 1/3 - smooth muscle

Question 8

What needs to open for food bolus to enter stomach

Answer 8

Relaxation of the lower oesophageal sphincter

Question 9

What are the functions of the stomach

Answer 9

temporary store of indigested material
Dissolve food particles and initiate digestion
Control delivery to duodenum
Produce intrinsic factor for B12 absorption

Question 10

What is the area at top of stomach called

Answer 10

cardiac region

Question 11

What is the area at the end of the stomach called

Answer 11

Pyloric region