Gastrointestinal system

Question 1

what is the primary function of the GI tract

Answer 1

absorption of dietary nutrients maximised by secretions added to convert large molecules to smaller ones

Question 2

what are the other GI functions

Answer 2

storage and secretion

Question 3

what is the mucosa made up of and where is it found

Answer 3

epithelium, lamina propria, muscularis mucosa

nearest the lumen, inside

Question 4

what is lamina propria

Answer 4

CT , has nerves, blood and lymph vessels

Question 5

what is the muscularis mucosa

Answer 5

thin layer of smooth muscle

Question 6

what is the submucosa layer and where

Answer 6

thicker layer with similar composition to lamina propria (CT)
contains submucosal plexus
middle

Question 7

what is the muscularis externa

Answer 7

circular muscle, myenteric plexus and longitudinal muscle

Question 8

what does the ENS do

Answer 8

coordinates contractions to mix and move contents between compartments

Question 9

what is the serosa layer

Answer 9

outmost layer of CT and squamous cells

some tract sections dont have this layer

Question 10

what 3 divisions of the ANS regulate the Gi function

Answer 10

parasympthetic
sympathetic
enteric

Question 11

what does the PNS do

Answer 11

signals stimulate GI secretions and motility facilitating digestion and absorption of nutrients

Question 12

what does the SNS do

Answer 12

decreases GI secretions and motility

Question 13

how does the ENS work

Answer 13

can operate independenly and is involved with reflexes and majority of GI functions

Question 14

what are the main plexuses in the ENS

Answer 14

myenteric

submucosal

Question 15

what does the myenteric plexus do

Answer 15

motility

regulates intestinal smooth muscle , contractions of muscles

Question 16

what is motility

Answer 16

coordinated contraction and relaxtion of muscles in the Gi tract

Question 17

what does the submucosal plexus do

Answer 17

secretions, regulates secretions and local absoptive environment

Question 18

what do reflexes in the ENS do

Answer 18

If one thing is going onn in one place then it can influence whats happening in another part

Question 19

how do they reflexes in the ENS communicate?

Answer 19

they are neural circuits with mechanoreceptors or chemoreceptors that then causes nerves to signal to regulate endocrine or secretory cells

Question 20

what are some GI neurotransmitter examples

Answer 20

enkephalins (contrict circular muscle around sphincters), ACh, serotonin

Question 21

what are some GI hormones (endocrine)

Answer 21

gastrin, cholecystokinnin, motilin, secretin

Question 22

what are paracrines

Answer 22

hormones released that act locally

Question 23

examples of paracrines

Answer 23

histamine, prostaglandins , somastostatin

Question 24

what are the 3 digestive phases

Answer 24

cephalic phase, gastric phase and intestinal phase

Question 25

what is the cephalic phase

Answer 25

triggered by thought of food , primarily neural, stimulates secretion

Question 26

what is the gastric phase

Answer 26

begins when food and oral secretions enter the stomach, coincides with distension (expansion of stomach). hormonal, neural and paracrine

Question 27

what is the intestinal phase

Answer 27

when stomach contents recah the duodenum

primarily hormonal but also other 2

Question 28

what is the role of the upper GI tract

Answer 28

minimal role in nutrient absorptionm transports and prepares food to be absorbed

Question 29

parts of the upper GI tract

Answer 29

mouth, salivary glands, oesophagus,stomach

Question 30

what does the mouth do

Answer 30

reduces food to optimal size, mixes food with secretions from 3 salivary glands (submandibular, parotid, sublingual)

Question 31

what is mastication

Answer 31

chewing

Question 32

swallowing (oesophagus)

Answer 32

• intiated voluntarily, involuntary after
• parasympathetic
• from mouth to upper oesophageal sphincter

Question 33

peristalsis in the oesophagus

Answer 33

series of coordinated muscle contraction/relaxtion

commences after upper oesopheageal sphincter

Question 34

functions of the stomach

Answer 34

3 primary motility functions
mixing via slow wave-intiated contractions, retropulsion and gastric emptying

accept and store food
mix food with secretions
digest food
deleiver food to small intestine

Question 35

stomach secretions

Answer 35

dervived from gastric invaginations (pits) which contain multiple cell types to secrete different secretions

Question 36

how do salivary secretions get produced

Answer 36

controlled by sympathetic and parasympathetic
cl, na and water are transported to duct lumen
ductal cells modify by reabsorbing na and cl and secreting K and HCO3 -

Question 37

examples of gastric secretions

Answer 37

ions and water, mucus from mucous neck cells, pepsinogen from cheif cells , H+ from parietal cells

Question 38

what are the sections of the small intestine

Answer 38

duodenum
jejunum
illeum

Question 39

what is the role of the small intestine

Answer 39

most macronutrient , vitamin and mineral absorption occurs (big SA)

Question 40

what are the parts of the large intestine

Answer 40

caecum, ascending, transverse, descending and sigmoid colon
rectum
anus

Question 41

role of large intestine

Answer 41

significant water and ion absoprtion

motility of contents :mixing and propulsion

Question 42

waht does motility in the small intestine involve

Answer 42

mixing via segementation and propulsion via peristalsis

Question 43

what does motility in the large intestine involve

Answer 43

segementation, peristalsis and mass movement and reflexes that control sphincter contraction and relxation

Question 44

what does the ileocecal sphincter regulate

Answer 44

amount of chyme entering the large intestine