Structure + Function of the GI Tract

Question 1

what is aboral movement?

Answer 1

movement from mouth to anus

Question 2

what is oral movement?

Answer 2

movement from anus to mouth

Question 3

what are the roles of the mouth?

Answer 3

chops food
starts carbohydrate digestion
propels food to the oesophagus

Question 4

what is the role of the oesophagus?

Answer 4

propels food to the stomach via peristalsis

Question 5

what are the roles of the stomach?

Answer 5

stores + churns food
continues carb digestion
initiates protein digestion
regulates delivery of chyme to duodenum

Question 6

what are the three parts of the small intestine?

Answer 6

duodenum
jejunum
ileum

Question 7

what is the principal site of digestion and absorption of nutrients?

Answer 7

the small intestine

Question 8

what are the three parts of the large intestine?

Answer 8

caecum
appendix
colon

Question 9

what parts is the colon divided into?

Answer 9

ascending
transverse
descending
sigmoid

Question 10

what are the roles of the colon?

Answer 10

reabsorbs fluid + electrolytes

stores faecal matter

Question 11

what is the role of the rectum and anus?

Answer 11

regulated expulsion of faeces

Question 12

what are the accessory structures of the GI tract?

Answer 12

salivary glands
pancreas
liver
gallbladder

Question 13

what makes up the hepatobiliary system?

Answer 13

the liver and the gallbladder

Question 14

name the layers of the GI tract wall, from inner to outer

Answer 14

mucosa
submucosa
muscularis externa
serosa

Question 15

what are the three layers of the mucosa?

Answer 15

mucous membrane (epithelium)
lamina propria
muscularis mucosae

Question 16

what is the submucosa made of?

Answer 16

connective tissue

Question 17

what neurone network is found in the submucosa?

Answer 17

the submucous plexus

Question 18

what are the two layers of the muscularis externa?

Answer 18

inner circular layer

outer longitudinal layer

Question 19

what does contraction of the inner circular muscle of the muscularis externa do?

Answer 19

narrows and lengthens the lumen

Question 20

where is the myenteric plexus found?

Answer 20

between the two layers of the muscularis externa

Question 21

what is the role of the myenteric plexus?

Answer 21

it governs the muscle activity of the GI tract

Question 22

what does contraction of the outer longitudinal muscle of the muscularis externa do?

Answer 22

shortens and widens the lumen

Question 23

what is the serosa made of?

Answer 23

connective tissue

contains secretory cells

Question 24

what are the four major functions of the alimentary canal?

Answer 24

motility
secretion
digestion
absorption

Question 25

what parts of the GI tract contain skeletal muscle?

Answer 25

mouth pharynx upper oesophagus external anal sphincter

Question 26

what type of muscle is most common for motility in the GI tract?

Answer 26

smooth

Question 27

what is chemical digestion?

Answer 27

chemical breakdown of complex foodstuffs into small absorbable units

Question 28

what are the two types of digestion?

Answer 28

chemical | physical

Question 29

what is physical digestion and where does it occur?

Answer 29

the chopping and churning of food in the mouth, stomach and small intestine

Question 30

what does contraction of the muscularis mucosae cause?

Answer 30

a change in the absorptive and secretory area of the mucosa also mixes the contents of the lumen, ensuring it is all digested

Question 31

why are smooth muscle cells in the GI tract electrically coupled, and what couples them?

Answer 31

to allow the slow wave of depolarisation to spread across the muscle coupled by gap junctions

Question 32

what are the muscle cells in the digestive system called?

Answer 32

single unit muscle cells

Question 33

what cell drives the slow wave electrical activity of the GI tract and what type of cell is this?

Answer 33

interstitial cells of cajal (ICCs) pacemaker cells

Question 34

when does contraction in the intestine occur?

Answer 34

only when slow wave amplitude is sufficient to reach threshold and triggers smooth muscle cell calcium action potentials

Question 35

what is the force of intestinal contraction related to?

Answer 35

the number of AP's discharged this is driven by the time the slow wave is above threshold

Question 36

what are slow waves also known as?

Answer 36

the basic electrical rhythm (BER)