the upper GI tract

Question 1

what is the purpose of the mouth for digestion?

Answer 1

Begins the breakdown of food through mastication. contains saliva for starch and glycogen breakdown, saliva also lubrictes the food. Bolus is produced and the tongue pushes it to the pharynx.

Question 2

what is bolus?

Answer 2

mixture of food and saliva.

Question 3

what is the structure of the pharynx?

Answer 3

a funnel shaped opening, surrounded by a mucous membrane and skeletal muscle

Question 4

why is the pharynx called the common passage way?

Answer 4

because air and food can enter

Question 5

where does food enter the oesophagus?

Answer 5

the upper oesophageal sphincter

Question 6

what is the function of the two oesophageal sphincters?

Answer 6

there are 2 (upper and lower), upper= food entry, the lower prevents stomach acid from entering the oesophagus.

Question 7

what is the structure of the oesophagus?

Answer 7

it is a muscular tube with thin walls to allow it to stretch. the upper third is made of skeletal muscle but the lower third is made of smooth muscle.

Question 8

what is deglutination controlled by and what are the three phases?

Answer 8

deglutination is controlled by the autonomic nervous system. it has the oral phase, pharyngeal phase and the oesophageal phase.

Question 9

what is the oral phase?

Answer 9

voluntary. bolus is formed

Question 10

what is the pharyngeal phase?

Answer 10

involuntary. where the bolus moves through the pharynx via peristalsis.

Question 11

what is the oesophageal phase?

Answer 11

involuntary. waves of peristalsis moves bolus through oesophagus, the lower oesophageal sphincter relaxes allowing the bolus to enter the stomach

Question 12

what is the function of the stomach?

Answer 12

to store large volumes of food and to mix it with gastric juices to produce chyme. it controls the release of chyme into the small intestine

Question 13

what is the structure of the stomach?

Answer 13

fundus (upper), allows extension.
body (middle) which contains mucosa that fold into rugae, also where gastric pits are found. the antrum (lower) it is muscular and involved in stomach content mixing + emptying.

Question 14

what do the gastric pits lead into?

Answer 14

gastric glands

Question 15

what are the 3 types exocrine secretions that gastric glands contain and what is their purpose?

Answer 15

neck cells- secrete mucus
chief cells- secrete pepsinogen
parietal cells- secrete HCl
enteroendocrine- secrete gastrin

Question 16

what is gastric juice made up of and what is each components purpose?

Answer 16

mucus- protect mucosa from low pH
HCl- kill bacteria
pepsin- activated by low pH
intrinsic factor- absorbs vit B12
gastric lipase- breaks down triglycerides