Lecture 1 Flashcards
What does the cardiac sphincter do?
Controls the movement of fluid
What is the pylorus?
A sphincter which is better than the cardiac sphincter and can empty out its material into the duodenum
Describe the muscular anatomy of the stomach
Muscle increases from the top to the bottom, there is more muscle in the antrum than in the fundus
What is the body of the stomach also called?
The corpus which is Latin for body
What are the layers of the stomach wall?
Mucosa, submucosa, muscularis externa and the serosa
What produces mucus in the stomach?
Epithelial cells NOT goblet cells
When are goblet cells found in the stomach?
The only time goblet cells are found in the stomach is in a pre cancerous stage e.g. gastric metapalasia
What is the lamina propria?
A type of connective tissue found under the thin layer of tissues covering a mucous membrane
What type of cells are found in the gastric glands?
Mucus secreting neck cells, parietal cells, chief cells and endocrine cells
Where do mucus cells migrate to?
They migrate to form the epithelium of the surface of the stomach and they secrete mucus
What are gastric pits?
They are indentations in the stomach which are entrances to the tubular shaped gastric glands
How often if the epithelium lining of the stomach replaced?
Every 72-96 hours
How long is the acid secreting cell life span?
150-200 days
What are known to survive longer than epithelial cells?
Glands
What do parietal cells secrete?
They secrete an extrinsic factor (VITAMIN B12)
What do Enterochromafin secrete?
Serotonin
What do Enterochromafin like cell secrete?
Histamine
What do D cells secrete?
Somatostatin
What do cells in the antrum secrete?
They don’t secrete acid but they do secrete pepsinogen and contain other endocrine cells called G cells which secrete gastrin
What is the first line of defence in the stomach?
Mucus is the first line of defence against gastric juice - which is secreted by epithelial cells
What cells line the oesophagus?
Stratified squamous cells
Describe the gastric mucus layer
It is a bilateral which protects the stomach from gastric juices, consisting of 2 layers of
What are the two layers in the gastric mucus bilayer?
A shear compliment layer and a shear resistance layer
What happens to the shear compliant layer when force is applied?
It becomes a viscous liquid - lubricant
What happens to the shear resistance layer when force is applied?
It remains intact
How many microns thick is the resistant layer?
150 microns
How thick is the compliant layer?
It has a variable thickness
What maintains the mucus layer?
Secretion and degradation are important in maintaining the balance - a dynamic balance is important in maintaining the thickness of the mucus layer
What is the composition of gastric juice?
Mucus, lipases, pepsins, intrinsic factor, water, ions and salivary amylase
Where is acid produced in the stomach?
It is only produced in the fundus and corpus of the stomach so lipase is only activated here
What is the optimal pH for lipase?
pH7
What can be used to stimulate acid secretion?
Histamine and gastrin
What pumps are used for acid secretion?
H+/K+, they are trafficked into the membrane during acid secretion and require ATP
What is tubulocisternae?
When there is a stimulus for acid secretion, they move along to the membrane and secrete acid
What are tubulocisternae supposed by?
An actin scaffold
What happens to the actin scaffold when there is a stimulus to stop acid secretion?
The actin scaffold is dissolved
What is a treatment for a gastric ulcer?
H2 antagonist - which are the receptors that have been stimulated to secrete acid
What is another treatment for gastric ulcers?
Proton pump inhibitors e.g. omeprazole which inhibit the function of the proton pumps
What happens in acid secretion?
Carbonic anhydride dissociates into H+ and bicarbonate. Bicarbonate is transferred out cross the basolateral enxyme.
What is the proton pump used for in acid secretion?
Transferring K+ coming in and H+ coming out
What is an active ingredient?
Sulfenimide - it has a spare SH group so it can form disuphide bridges with cystine
What is bad about people who are taking proton pump inhibitors?
If you are told to stop taking them usu will have a huge acid secretion and that can cause damage so you have to keep taking the tablets
