The stomach : acid production , swallowing and vomiting Flashcards
(30 cards)
where are lingual taste buds located
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
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
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
food passage moves by what
peristalsis not gravity
lining of the oesophagus is of what cells
stratified squamous epithelium - good protection from trauma, smooth for food but a poor protection from the acid
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)
muscularis externa
what control the muscularis externa and is the main neuronal regulator of intestinal motor function
myenteric plexus
this lies between the circular and longitudinal layers of the muscularis externa
myenteric plexus increase what
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
in the oesophagus the upper ( striated), middle (mixture) and lower ( smooth) pars are under voluntary action initially then become reflex. what nerve innervates it
vagus nerve
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
stimulation affects secretions
how does the body protect from aspiration - describe pathway
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.
what nerves innervates the oesophagus in swallowing higher up and are critical to airway protection going on above
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.
at the oesophageal junction what muscle contributes to barrier function to prevent reflux
diaphragm
four main cells of the stomach
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
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
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
where would you find the stomach in the abdomen - what region
left hypochondriac to epigastric region
what do partial cells secret e
intrinsic factor and HCL
what do chief cells secrete
pepsinogen ( inactive)
what do G cells cells secrete
release gastrin
what do D cells secrete
somatostatin
gastric acid function
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.
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
gastric acid
Gastric lining protected against autodigestion by
mucus secreted by surface epithelial and mucous neck cells
bicarbonate secreted by epithelial cells under mucus layer
NSAID and gastric ulcer risk
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
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
what is a hunger contraction
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.
