Lecture 21 Flashcards
What is the peritoneum
A serous membrane that lines the abdomen
What does the parietal layer of the peritoneum line?
The body wall
What does the visceral layer of the peritoneum line?
The organs
What is between the parietal and visceral layers of the peritoneum?
Peritoneal cavity, a fluid-filled space
What is the retroperitoneal?
Area posterior to the peritoneum, organs anterior surface covered only
What is the mesentery?
A double layer of visceral peritoneum that connects an organ to the body wall
What is the omenta?
A double layer of visceral peritoneum that connects an organ to another organ
What is the stomach?
A J-shaped organ located at the base of the esophagus
Where does the esophagus pass through and what is this called?
The diaphragm, the esophageal hiatus
What is the lower esophageal sphincter?
A smooth muscle ring that prevents reflux
What is the gross structure of the stomach?
Cardia, fundus, body and pylorus
What is the cardia of the stomach?
Area closest to the heart
What is the fundus of the stomach?
The broad end (most superior), generally filled with gases
What is the pylorus of the stomach?
The area that controls the flow of chyme into the intestines
What is the function of the omenta?
To hold the stomach in place
What is the lesser omentum?
The stomach to the liver
What is the greater omentum?
The stomach to the transverse colon
What are the layers of the stomach?
Mucosa, submucosa and muscularis
(No adventitia layer, however, has a layer of serosa which is NOT one of the 3 official walls of the stomach, just a protective layer of connective tissue)
What are the modifications to the mucosa?
In-folding in the simple columnar epithelium increases surface area for secretion via gastric glands
What are the modifications to the submucosa?
Contain rugae
What are rugae?
Temporary folds that allow for the expansion of the stomach, at the core of the submucosa and are important for storage purposes.
What are the modifications to the muscularis?
Three layers inner to outter; oblique, circular, longitudinal
Why is the muscularis modified?
For motility
What are the gastric glands?
Any of the branched tubules in the inner lining of the stomach that secrete gastric juice and protective mucus
What is the purpose of the gastric glands?
To provide the stomach with the necessary acid and enzymes for digestion, mucous for protection and hormones for regulation
What is the anatomy of the gastric glands?
Begin with the pits that are lined by epithelial goblet cells
What is the purpose of the epithelial goblet cell lining of the gastric pit?
To secrete mucus for protection and lead into the glands
What are the three cells within the gastric gland?
Parietal cells, G cells and chief cells
What is the purpose of the parietal cells?
To secrete acid and intrinsic factor for digestion
What is the purpose of the G cells?
To secrete hormones for regulation
What is the purpose of the chief cells?
To secrete pepsinogen, an inactive precursor of pepsin which is an enzyme for digestion
What is the histology of the chief cells?
Abundant rough ER, apical zymogen granules and a basal nucleus
With is the histology of the parietal cells?
Abundant mitochondria, central nucleus, microvilli and canaliculi, pumps H+
What is a microvilli?
Folded structures to increase surface area
What is a canaliculi?
The channels between the microvilli where the H+ are released
What is the endocrine control of the stomach?
Stomach contains endocrine cells in the mucosa; gastrin and ghrelin are secreted into the blood stream
What is the neural control of the stomach?
Enteric nervous system (ENS) provides local reflexes and primary control. CNS modulates ENS function - long neural reflexes
What separates the stomach and small intestine?
Pyloric sphincter
What is chyme?
Partially digested food
What does the chyme entering the SI require?
Further digestion from enzymes
What does the SI require as chyme enters?
Protection from the acid; given by mucus and neutralising acid
What is the neutralising acid?
Enzymes and bicarbonate
What provides the mucus in the SI?
The glands of the submucosa of the duodenum
Where are the enzymes and bicarbonate provided from for the SI?
The pancreas
What is the pancreas?
A retroperitoneal, stationary organ with its head in the C-shaped duodenum and tail pointing to the spleen
Where does the pancreas lie?
Posterior to the stomach
What two functions does the pancreas have?
Endocrine and exocrine
What is endocrine function?
Hormones send through the blood to organs
What is exocrine function?
Secretion of products directly onto organ surface
What is the endocrine function of the pancreas?
Pancreatic islet alpha cells secrete glucagon and pancreatic islet beta cells secrete enzymes
What is the exocrine function of the pancreas?
Acinar cells secrete enzymes and duct cells secrete bicarbonate
What are pancreatic acinar cells?
Apical zymogen granules with a basal nucleus and abundant rough ER
Where do the bile duct and pancreatic ducts meet?
At the entrance to the hepatopancreatic ampulla
What is the duodenal papilla?
The point where the dilated junction of the pancreatic duct and the bile duct enter the duodenum which projects into the duodenal lumen
What controls the release of secretions from the pancreas?
The hepatopancreatic sphincter
