digestive system 04/15

what are the main functions of the stomach?

churns food (mechanical digestion) and mixes it with gastric juice

chemical digestion to break down food into chyme

what is the gross anatomy of the stomach?

connects the esophagus to the duodenum and is located in the upper left part of the abdomen

what prevents the gastric juice from eating away at the stomach itself?

cells secrete a layer of mucus-protective lining, and the epithelium is constantly regenerating

what is a peptic ulcer?

the erosion of the wall of the stomach (gastric ulcer) or duodenum (duodenal ulcer)

what causes a peptic ulcer?

the ‘balance’ between acidic juice and mucosal repair is thrown off— so acid eats away at the lining

helicobacter pylori infection

what are the functions of the small intestine?

finish the chemical digestion process

absorbs most (90%) of all nutrients

what is the gross anatomy of a small intestine?

the duodenum, jejunum, and ileum

what is the duedenum?

the first part of the small intestine, it receives chyme from the stomach,

receives bile from the liver/gallbladder, and pancreatic enzymes from the pancreas through the duodenal papilla

what is the jejunum?

the second part (2/5) of the small intestine and has a huge surface area

what is the ileum?

the third part of the small intestine, which connects to the cecum of the large intestine, has few folds but contains more MALT

has an immune function and is the primary line of defense

what are circular folds?

folds of mucosa and submucosa in the small intestine

what are the functions of the circular folds?

increase surface area so nutrients can be absorbed\

slow down the chyme and allow it to mix with intestinal juices, allowing time for full nutrient absorption (“speed bumps”)

what are the functions of the villi in the circular folds?

increase surface area to provide great distance for materials to be ingested and absorbed

what is the function of the lacteal?

absorb lipids and fat-soluble vitamins (a,d,e,k)

what are the functions of the large intestine?

absorption of water and electrolytes

storage of undigested material (feces) until it can be expelled

what are the segments of the large intestine?

the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum and anal canal

what attaches to the cecum?

the ileum and vermiform appendix

how does feces leave the anal canal?

through the anus (external opening)

what is colorectal cancer?

cancer in the large intestine (colon) or rectum

what does most colorectal cancer arise from and what is an early symptom?

most arise from polyps (growth) from the mucosa and an early sign is blood in stool/feces

how does colorectal cancer get diagnosed?

through a colonoscopy to examine the colon

what is the function of the liver?

produce and secrete bile (helps with fat/lipid digestion)

processes the products of digestion (including alcohol & drugs)

stores glycogen (carbohydrate formed from glucose)

what two hormones affect the liver’s storage of glycogen?

insulin and glucagon

what are the 4 lobes of the liver?

right, left, and on the posterior side quadrate and caudate

what do hepatocytes do?

produce bile that exits the liver via the bile duct

what does the central vein form?

the hepatic veins which drain blood out of liver to the inferior vena cava

what does the portal triad consist of?

the branch of the hepatic portal vein, the branch of the hepatic artery, and the branch of the bile duct

what does the gallbladder do?

stores and concentrates bile secreted by the liver

what are gallstones (cholelithiasis)?

condensations of bile material into stones that form in the gallbladder, its painful if they travel through the biliary apparatus

what do the acinar cells of the pancreas do?

secrete pancreatic juice (digestive enzymes & bicarbonate)

what is the function of pancreatic juice?

neutralize the acidic chyme and continues chemical digestion

how does pancreatic juice leave the pancreas?

via the pancreatic duct

what is the biliary apparatus?

a network of ‘tubules’ that transport bile and pancreatic juice to the duodenum

what do the right and left hepatic duct form?

the common hepatic duct

what do the cystic and common hepatic ducts form?

the common bile duct

what do the common bile and pancreatic duct open into?

the duodenum at the duodenal papilla

what does the duodenum secrete?

bile and pancreatic juice

what is part of the arterial supply to the abdominal GI tract?

the celiac trunk, superior mesenteric artery, and inferior mesenteric artery

what is part of the venous drainage of the abdominal GI tract?

the hepatic portal system

what is the hepatic portal system?

veins that drain blood from the GI tract directly to the liver

what are the four main veins of the hepatic portal system?

the splenic, superior mesenteric, inferior mesenteric, and hepatic portal vein

what does the hepatic portal vein receive blood from?

the splenic, superior mesenteric, and inferior mesenteric veins

what is blood from the hepatic portal vein processed by?

liver cells (hepatocytes)

how does blood leave the liver once it’s processed?

via the hepatic veins and into the inferior vena cava