Stomach I Flashcards
What are the two functional regions of the stomach?
Proximal (fundus and proximal body) - receives ingested meal
Distal (caudad) - responsible for contractions that mix food and propel it into duodenum
What is receptive relaxation?
PRoximal stomach relaxes to accommodate ingested meal
Mediated by vagovagal reflex, which is initiated by distension of stomach and abolished by vagotomy
Describe peristalsis in the stomach?
Peristaltic contractions originate in pacemaker region in midstomach and proceed distally
As they move distally toward pylorus both velocity and force of contraction increase
What is retropulsion?
Wave of contraction closes distal antrum and pyloric sphincter before chyme reaches there
Causes most of chyme to be propelled back into stomach to be mixed
What are migrating myoelectric complexes?
Contractions that occur at 90-minute intervals during fasting
Clear stomach of any residual food, cause hunger contractions, abolished by eating
What does the rate of gastric emptying depend on?
Liquids empty faster than solids
Carbs > protein > fat ——————– faster > slower
Controlled mostly by signals from the duodenum
What stimuli from the duodenum inhibit gastric emptying?
High [H+]
Presence of fat or protein products
Non-isotonic solutions
Increased distension of proximal stomach
Increased pressur in proximal small intestine
What is gastroparesis?
Impaired/Delayed emptying
Fullness, loss of appetite, nausea, vomiting
Most common cause is diabetes, but also anticholinergics and neuro disorders
What are potential consequences of increased gastric emptying?
Diarrhea because of increased osmotic load in small intestine
Duodenal ulcers due to stomach acid entering the duodenum
What is dumping syndrome?
Occurs when lower end of small intestine fills too quickly with undigested food from stomach
Common after stomach surgery
Early phase symptoms - nausea, vomiting, diarrhea
Late phase symptoms - sweating, weakness, dizziness
Due to too much fluid in intestine and hypoglycemia
What is the oxyntic gland mucosa?
Proximal stomach mucosa that secretes acid, pepsinogen, intrinsic factor and mucus
What is pyloric gland mucosa?
Located in distal stomach
Secretes mostly gastrin, with some mucus and pepsinogen
What is the role of parietal cells and chief/peptic cells in oxyntic glands?
Parietal - secrete acid and IF
Chief/Peptic - Secrete pepsinogen
What is the function of HCl in the stomach?
Begins digestion of dietary protein
Converts pepsinogen
Kills most bacteria that enters stomach - lack of acid production can lead to bacterial infections
What is the function of pepsin in the stomach?
Begins digestion of protein by splitting interior peptide bonds
Vagal stimulation causes greatest increase in secretion
