The stomach : acid production , swallowing and vomiting

Question 1

where are lingual taste buds located

Answer 1

Lingual taste buds are located mainly within protuberances termed papillae

Each of the fungiform (mushroom-shaped) papilla, found primarily on the tip and sides of the tongue, contains an average of six to nine taste buds

Question 2

what is a fungiform

and black hair tongue - due to hypertrophy of the centrally located filiform papillae which become yellow or black from contact with food or tobacco. Not involved in taste they help move and abrade food

Answer 2

mushroom shaped papilla

Each of the fungiform (mushroom-shaped) papilla, found primarily on the tip and sides of the tongue, contains an average of six to nine taste buds
They are located mainly in the central region of the tongue (Hypertrophy of these papillae results in “hairy tongue,” which becomes yellow or black from contact with food or tobacco

Question 3

food passage moves by what

Answer 3

peristalsis not gravity

Question 4

lining of the oesophagus is of what cells

Answer 4

stratified squamous epithelium - good protection from trauma, smooth for food but a poor protection from the acid

Question 5

what inner circular muscular layer and a longitudinal outer muscular layer have coordinated contractions ( peristalsis) to propel food through the GI tract.( stomach has a third muscularis external Layer - the inner oblique layer)

Answer 5

muscularis externa

Question 6

what control the muscularis externa and is the main neuronal regulator of intestinal motor function

Answer 6

myenteric plexus

this lies between the circular and longitudinal layers of the muscularis externa

Question 7

myenteric plexus increase what

Answer 7

Generally increases

1) smooth muscle tone
2) intensity of rhythmic conduction
3) frequency of contraction and
4) velocity of contraction

NB. Not all signals from myenteric plexus are excitatory
Depends on the neurotransmitter released

Question 8

in the oesophagus the upper ( striated), middle (mixture) and lower ( smooth) pars are under voluntary action initially then become reflex. what nerve innervates it

Answer 8

vagus nerve

Question 9

we already know that The myenteric plexus(nerve net: between longtitudinal and circular muscle layers and stimulation leads to contraction

The submucosal plexus between circular muscle layer and submucosa. what does stimulation of this affect

Answer 9

stimulation affects secretions

Question 10

how does the body protect from aspiration - describe pathway

Answer 10

food bolus pushed to back of tongue

then nasopharynx will close preventing nasal reflex.

glottis closes and the larynx gets pulled up and

food is channeled by the pyriform fossa - epiglottis diverts food lateral through the pyriform fossa( things either side of the glottic opening) acting as a snowplough over the larynx rather than a lid.

and a peristaltic wave is seen down the oesophagus.

Question 11

what nerves innervates the oesophagus in swallowing higher up and are critical to airway protection going on above

Answer 11

recurrent ( and sup) laryngeal nerves

these provide motor and sensory innervation to the larynx.

Below this the right and left vagus from plexus around the oesophagus emerging as anterior and posterior nerves.

Question 12

at the oesophageal junction what muscle contributes to barrier function to prevent reflux

Answer 12

diaphragm

Question 13

four main cells of the stomach

Answer 13

all epithelium (colomnar)

Mucous cells- alkaline mucus that protects
parietal cells - HCL
chief cells - pepsin
G cells - gastrin

stomach is largely sterile
makes chyme
partially digests food and steady flow

Question 14

the stomach is subdivided into the cardia ( by cardiac notch of oesophagus joining) , funds ( top) , body , pyloric Antrum , pyloric canal both making up the pylorus that then connects to the duodenum.

what cells are found in the body and fundus and what cells are found in the pyloric glands respectively

Answer 14

gastric glands
parietal cells
chief cell s
mucous cells

Pyloric glands
G -cells
D-cells
Mucous cells

pacemaker on the left side of body
also have greater and lesser curves - self explanatory

Question 15

where would you find the stomach in the abdomen - what region

Answer 15

left hypochondriac to epigastric region

Question 16

what do partial cells secret e

Answer 16

intrinsic factor and HCL

Question 17

what do chief cells secrete

Answer 17

pepsinogen ( inactive)

Question 18

what do G cells cells secrete

Answer 18

release gastrin

Question 19

what do D cells secrete

Answer 19

somatostatin

Question 20

gastric acid function

Answer 20

Kills ingested bacteria
Denatures proteins 🡪 particle breakdown
Facilitates:
 action of gastric lipase
Lipid digestion
and converts pepsinogen into pepsin for protein digestion 

proton pump moves hydrogen into gastric lumen and potassium the other way and chloride comes across with potassium on luminal side to make HCL. On basal side bicarbonate out and chloride in
co2 also in to combine with water to make carbonic acid which dissociates.

Question 21

these 3 phases
Cephalic - initiated by smell and taste mediated by vagus nerve

gastric - intimated by stomach with proteins and gastrin mediated via vagus and histamines

Intestinal - proteins in duodenum and inhibitory by ph and secretin and somatostatin ( direct action via gastrin)

these are regulation methods of what acid

Answer 21

gastric acid

Question 22

Gastric lining protected against autodigestion by

Answer 22

mucus secreted by surface epithelial and mucous neck cells

bicarbonate secreted by epithelial cells under mucus layer

NSAID and gastric ulcer risk

Question 23

in the stomach peristalsis is initiated by the pacemaker and waves towards the ants churning and breaking down food. chyme ( the fluid from the stomach to small intestine consisting of the gastric juice and digested food) can be returned to the stomach for further mixing. Occasionally what opens to allow a small mount of liquid chyme through to the duodenum

Answer 23

pylorus - pyloric sphincter - when waves gets there contrast stopping so only a few ml of chyme can enter with each mixing wave - focuses back in retropulsion -

As the peristaltic wave reaches the antrum, the intensity of contraction increases
This causes the contents within the antrum portion to become under higher and higher pressure

Question 24

what is a hunger contraction

Answer 24

Hunger contractions- Contractions are cyclic peristaltic contractions of body of stomach. Stimulated when the stomach is empty and has been for a few hours. Strongest in young healthy adults, strength of contraction can altered based on blood sugar levels. Level of contractions can be quite strong and can cause mild pain called hunger pangs; these are normally as a result of 12-24hrs after last ingested food, and the strength of these increase between 3-4days of starvation.

Question 25

what is retropulsion

Answer 25

forces contents of Antrum back up to main body of the stomach extremely important for mixing the stomach contents

Question 26

hormones that regulate stomach emptying include CCK and GIP in response to acidic and fatty chyme entering the duodenum.

in neuronal regualtion - what system does this

Answer 26

myenteric reflex - stretching of stomach promotes and increase effect of pyloric pump and inhibits the pylorus tone

enterogastric nervous reflexes - increase the pyloric tone - distention , irritation , protein , acidity , osmoliarty

Question 27

vomiting is a sequential reflex and protection against ingested toxins
what pathways are involved in vomiting

Answer 27

Vesitbular system - hsitmain type 1 receptors
chemoreceptors trigger zone - postrema - dopamine type 2 receptors

vomiting centre - nucleus of tracts solitary - histamine type 1 and ACH
cranial nerves 9 and 10

Question 28

emetic responses are triggered by the CTZ - chemoreceptor trigger zone( outside blood brain barrier) , labyrinth with motion via cranial nerve 8 and what else

Answer 28

the Cortex for sight, smell and anxiety

Question 29

the stomach has no role in vomiting mechanism - how does it work

Answer 29

insoraition so abode pressure increases , glottis closes preventing aspiration , dudeonu contracts blocking transit , the gastrooesphgeal sphincter relaxes and ado wall contract abruptly ejecting the gastric contents forcefully.

Question 30

Emetophobia

Answer 30

fear of throwing up