Anatomy Exam 3 - Digestive System Portion

Digestive System Function

physical and chemical breakdown of food, absorption of digested food chemicals into the bloodstream, elimination of wastes

Alimentary Canal

tube that acts to digest and absorb food chemicals

Peristalsis

adjacent segments of the alimentary canal organs alternately contract and relax

Segmentation

nonadjacent segments of the alimentary canal organs contract and relax

Homeostatic Imbalance - Mumps

painful to open mouth/chew or swallow acidic foods, moderate fever; carries a 25% risk of also infecting testes in adult males, which could lead to sterility

Dental Caries (Cavities)

demineralization of enamel and dentin from bacterial action; dental plaque (film of sugar, bacteria, and debris

Gingivitis

plaque calcifies to form calculus (tartar) which disrupts seal between gingivae and teeth; anaerobic bacteria infect gums

Periodontal Disease

immune cells attack not only bacterial intruders but also body tissues; can destroy periodontal ligament and activate osteoclasts; may increase heart disease and stroke, promotes atherosclerotic plaque formation, bacteria entering blood can cause clot formation in coronary and cerebral arteries

Hydrochloric Acid

stomach component; helps kill bacteria in food, activates pepsinogen to pepsin, aids mechanical digestion

Pepsinogen

stomach component; inactive protease (protein-digesting enzyme), activated to pepsin by exposure to low pH (HCl)

Gastrin

stomach component; secreted by enteroendocrine cells (G cells), increases secretion of gastric juice and increases gastric motility

Stomach Intrinsic Factor

enables the body to absorb vitamin B12 (needed to produce RBCs)

Gastritis

inflammation caused by anything that breaches the stomach’s mucosal barrier

Peptic or gastric ulcers

can cause erosions in stomach wall; if erosions perforate wall, can lead to peritonitis and hemorrhage

Acid-Reflux Disease

stomach contents are forced back into the esophagus, causing irritation; can result in esophageal ulcers

Gastric Motility

Propulsion, Grinding, Retropulsion

Propulsion

peristaltic waves move from the fundus toward the pylorus

Grinding

the most vigorous peristalsis and mixing action occur close to the pylorus, the pyloric end of the stomach acts as a pump that delivers small amounts of chyme into the duodenum

Retropulsion

peristaltic wave closes the pyloric valve, forcing most of the contents of the pylorus backward into the stomach a process that aids in mixing the gastric contents, ensuring thorough digestion before entering the small intestine.

Small Intestine Function

main organ of chemical digestion and absorption of food chemicals through enzymes and villi.

Liver

primary digestive function is the production of bile; secretion of bile, storage of carbohydrates, iron, and fat-soluble vitamins; synthesis of important biochemicals such as fats, glucose, and cholesterol; production of plasma proteins; removal of toxins from blood and regulation of metabolism.

Gallbladder

primary function is storage of bile and its release into the small intestine to aid in fat digestion

Liver Lobules

hexagonal structural and functional units; composed of plates of hepatocytes that filter and process nutrient-rich blood; central vein located in longitudinal axis with portal triads at each corner

Bile

yellow-green, alkaline solution containing bile salts and bilirubin, as well as cholesterol, triglycerides, phospholipids, and electrolytes

Bile Salts

cholesterol derivatives that function in fat emulsification and absorption

Bilirubin

pigment formed from heme

Gallstones

caused by too much cholesterol or too few bile salts; can obstruct flow of bile from gallbladder

Pancreatic Juice

made of enzyme-rich fluid and bicarbonate-rich fluid

Enzyme-Rich Fluid

contains a variety of hydrolytic enzymes capable of “breaking down” all types of large biochemicals

Bicarbonate-Rich Fluid

basic solution that neutralizes acid in chyme coming from the stomach

Cholecystokinin (CCK)

made in duodenal mucosa; stimulated by fatty chyme; targets stomach, liver, pancreas, gallbladder, and hepatopancreatic sphincter; inhibits stomach’s secretory activity; potentiates secretins actions; increases output of enzyme-rich pancreatic juice; stimulates organ to contract and expel stored bile; relaxes sphincter to allow entry of bile and pancreatic juice into duodenum

Glucose Dependent Insulinotropic Peptide (GIP)

made in duodenal mucosa; stimulated by fatty chyme; targets stomach and beta cells of the pancreas; inhibits HCl production; stimulates insulin release

Gastrin

made in G cells of stomach mucosa; stimulated by food in stomach and acetylcholine released by nerve fibers; targets parietal cells of stomach, small intestine, ileocecal valve, and large intestine; increases HCl secretion; stimulates gastric emptying; stimulates contraction of intestinal muscle; relaxes ileocecal valve; stimulates mass movement

Histamine

made in stomach mucosa; stimulated by food in stomach; targets stomach; activates parietal cells to release HCl

Intestinal Gastrin

made in duodenal mucosa; stimulated by acidic and partially digested foods in duodenum; targets stomach; stimulates gastric glands and motility

Motilin

made in duodenal mucosa; stimulated by fasting; targets proximal duodenum; stimulates migrating motor complex

Secretin

made in duodenal mucosa; stimulated by acidic chyme; targets stomach, pancreas, and liver; inhibits gastric gland secretion and gastric motility; increases output of pancreatic juice rich in bicarbonate ions; increases bile output

Serotonin

made in stomach mucosa ; stimulated by food in stomach; targets stomach; causes contraction of stomach muscle

Somatostatin

made in stomach and duodenal mucosa; stimulates by food in stomach and stimulation by sympathetic nerve fibers; targets stomach, pancreas, small intestine, gallbladder and liver; inhibits gastric secretion of all products; inhibits secretion; inhibits GI blood flow thus inhibits intestinal absorption; inhibits contraction and bile release

Vasoactive Intestinal Peptide (VIP)

made in enteric neurons; stimulated by chyme containing partially digested food; targets small intestine, pancreas, and stomach; stimulates buffer secretion; increases blood flow through intestinal capillaries; relaxes intestinal smooth muscle; increases secretion; inhibits acid secretion

Cirrhosis

progressive, chronic inflammation from chronic hepatitis or alcoholism

Pancreatitis

inflammation of the pancreas as digestive juices or enzymes attack

Bacterial Flora

consists of 1000+ types; ferment indigestible carbohydrates and mucin, releasing irritating acids and gases; synthesize B complex and some vitamin K needed by liver to produce clotting factors; keep pathogenic bacteria in check