Stomach et Flashcards
(23 cards)
Name the parts of the stomach
cardia, fundus, body, antrum, pylorus
What are the anatomical surfaces of the stomach?
Greater curvature, lesser curvature, cardial notch (gastroesophageal junction), angular incisure
What are the histological zones of the stomach?
Cardia- mucus secretion
Fundus and body- mucus and gastric juices secretion
Pylorus- mucus secreting and endocrine cells
What is the lining of the stomach?
Simple Columnar Epithelium
Describe the roles between somatostatin, acid secretion etc
Acetylcholine stimulates G cells to produce gastrin and parietal cells to produce acid. gastrin also stimulates the parietal cells to produce acid. gastrin stimulates ECL to release histamine. histamine via the H2 receptor increases acid secretion on the parietal cell, whilst inhibiting somatostatin production from D cells via the H3 receptor. somatostatin inhibits acid secretion and histamine secretion
How do the oesophagus and stomach protect themselves from acid?
There is a thickening of smooth muscle at the gastro-oesophageal junction, known as the lower oesophageal sphincter. the stomach is lined with simple columnar epithelium from which mucous secretions full of bicarbonate provide protection from the acid
what do the parietal and chief cells secrete?
parietal cells secrete HCL, whilst chief cells secrete pepsinogen which becomes pepsin in the presence of acid. pepsin aids in the breakdown of peptides.
How are carbs digested?
carbs are digested by pancreatic enzymes in the duodenum. (e.g. alpha amylase) and by specific enzymes in the brush border
how are fats digested?
pancreatic lipase degrades the fat lipids to mono chains and fatty acids. their presence promotes lipid emulsification. the emulsion is then coated by bile salts from bile. these micelles are then transported around the body in the bloodstream
how are proteins digested?
by gastric pepsin and pancreatic endo/exo peptidases.
what are the two sections of small intestinal motility?
segmentation- mixing of chyme by moving it back and forth
peristalsis- movement of chyme downstream.
what is the role of the colon?
fluid and electrolyte absorption. the breakdown of carbs by bacteria in the colon produces 7% of the daily energy needs.
how does pooping happen?
upon rectal distension, the internal sphincter is relaxed. when the external sphincter which is under voluntary control and puborectalis muscles are relaxed then faeces can pass.
What is the cephalic phase?
Phase where vagus nerve stimulates parietal cells to produce acid upon sight, smell or thought of food.
What is the gastric phase?
where the food in the stomach activates G cells in the antrum and pylorus of the stomach to secrete gastrin which stimulates ECL cells and parietal cells to produce histamine and more acid respectively
how is acid regulated?
high levels of hydrogen ions signal D cells to produce somatostatin, inhibiting G cells from releasing more gastrin
What cells in the stomach produce what?
G cell- gastrin D cell- somatostatin ECL cell- histamine parietal cell- HCL chief cell- pepsinogen mucus cells- mucus
What are the nine quadrants of the abdomen?
Right, left hypochondrium Right, left groin epigastric region umbilical region right, left flank pubic region
What are the four layers throughout the GI tract?
Mucosa- lined with epithelium closest to lumen, then laminae propria a type of connective tissue and then muscularis mucosae which provides the contractions
Submucosa- contains blood vessels, nerves and lymphatics
Muscularis propria- smooth muscle layer, two layers of inner circular (IC) and outer longitudinal (OL)
Serosa- loose connective tissue providing support
What level does the oesophagus (OP) enter the diaphragm and where?
through the OP hiatus around the tenth vertebra. the hiatus is made by the right crus muscle
what are the linings of the stomach and op?
stratified squamous in the op and simple columnar in the stomach
Describe the blood supply to the stomach
the stomach is supplied by three branches of the celiac trunk, common hepatic/ left gastric and splenic arteries.
the left and right gastric run along the lesser curvature
the short gastric supply the fundus
left and right gastro-omental arteries run along the greater curvature, the left branches from the splenic and the right from the gastroduodenal
What are the greater and lesser sacs and how do they communicate?
potential space between the peritoneums of the abdomen. they communicate through the omental foramen.
