5. The Digestive System

Question 1

how long is the GI tract

Answer 1

4.5 metres long

Question 2

what are the 4 basic processes of the digestive system:

Answer 2

1. digestion- breakdown of food
2. absorption- transport of food into bloodstream
3. motility- peristaltic activity of muscle propelling food along GI tract
4. secretion- transport of digestive fluids into GI tract

Question 3

name the accessory glands of the digestive system

Answer 3

pancreas
liver
gall bladder
salivary gland

Question 4

what are the 5 components of the lumen

Answer 4

mucosa, submucosa, muscularis, serosa, nerve plexus

Question 5

what does the submucosa consist of

Answer 5

connective tissue
blood
lymphatic vessels

Question 6

what does the serosa consist of

Answer 6

connective tissue

protective layer

Question 7

what does exocrine mean

Answer 7

secretion of enzymes into a duct directed at a target

Question 8

what does endocrine mean

Answer 8

secretion of hormones into the bloodstream

Question 9

how often is the mucus membrane replaced in an adult

Answer 9

every 5 days

Question 10

what nervous system stimulates saliva response

Answer 10

the autonomic nervous system

Question 11

what enzymes are found in saliva

Answer 11

salivary alpha-amylase and lingual lipase

Question 12

name 3 other functions of saliva

Answer 12

lubrication
antibiotic action (lysozyme)
cleans teeth

Question 13

what does the oesophagus connect

Answer 13

the pharynx to the stomach

Question 14

how does heartburn occur

Answer 14

Backflow of upper and lower esophageal sphincters

Question 15

what types of muscle are found in the oesophagus

Answer 15

upper 1/3 skeletal muscle

lower 2/3 smooth muscle

Question 16

what is the function of parietal cells

Answer 16

secrete hydrochloric acid

Question 17

what is the function of chief cells

Answer 17

secrete pepsinogen

Question 18

what is pepsinogen

Answer 18

a zymogen of pepsin

Question 19

parietal cells also secrete intrinsic factor, what is this

Answer 19

a glycoprotein required for the absorption of vitamin b12 in the ileum

Question 20

what is the function of rennin

Answer 20

coagulates milk

Question 21

what are the 4 regions of the stomach

Answer 21

fundus
body
antrum
pyloris

Question 22

stomach is lined with gastric pits containing what cells

Answer 22

neck cells
chief cells
parietal cells

Question 23

what is the function of neck cells

Answer 23

produce mucus, found at the top of the mucus pit

Question 24

what hormone triggers the release of pepsinogen and HCL

Answer 24

gastrin

Question 25

what nerve is important in rest and digest in the stomach

Answer 25

the vagus nerve

Question 26

how does HCL form

Answer 26

H+ → transported into the lumen for K+ ions
Bicarbonate ions→ exchanged for chloride ions which diffuse into the lumen

= HCL accumulation in the lumen

Question 27

what is the function of zymogens

Answer 27

zymogens are enzymes in an inactive form, prevents them from becoming reactive in the cells where they were produced

Question 28

what activates pepsinogen

Answer 28

when it encounters HCL in the stomach

Question 29

what is the difference between an endopeptidase and an exopeptidase

Answer 29

endo= break internal peptide bonds= smaller fragments

exo= removes one amino acid at a time from either end of a polypeptide

Question 30

how long is the small intestine

Answer 30

2.5-3 metres

Question 31

what makes up the first 30cm of the small intestine

Answer 31

the duodenum, the jejunum and ileum

Question 32

the duodenum is responsible for digestion. what aids it in its role?

Answer 32

chyme from the stomach
enzymes from pancreas
bile from the liver and gallbladder

Question 33

what is the function of the Crypts of Lieberkühn

Answer 33

secrete bicarbonate-rich fluid to neutralise chyme from the stomach

Question 34

what 4 structures make up the colon

Answer 34

cecum, rectum, anal canal, appendix

Question 35

what is the function of the colon

Answer 35

principle site of water absorption

main site of commensal microflora (digestive bacteria)

Question 36

true or false:

there are crypts of Lieberkühn present in the colon but no villi

Answer 36

true