9. GI system Flashcards
Digestion vs absorption
breakdown of food into organic molec (ex: starches and carbs to monosaccharides, proteins to amino acids) vs transporting food from GI tract to circulatory system
Mechanical digestion vs chemical digestion. Intracellular digestion vs extracellular digestion
physical break down of food (mastication) vs enzymatic cleavage of bonds in food (saliva/salivary glands). oxidation of glucose and fatty acids for energy vs obtaining nutrients from food in alimentary canal
Name parts of alimentary canal; how are they sectioned off?
mouth/oral cavity, pharynx, esophagus, stomach, small intestine, large intestine/colon, rectum, anus; sphincters
What is peristalsis? Which nervous system is responsible for this?
Contractions that move food throughout digestive tract. Parasympathetic nervous system (remember “rest and digest”), specifically enteric nervous system
What is salivary amylase and lipase?
Enzyme in saliva that hydrolyzes starch into smaller sugars; aka ptyalin. Lipase hydrolyzes lipids
What are the 3 parts of the pharynx? (Use prefixes to determine their location)
nasopharynx, oropharynx, laryngopharynx (above vocal cords)
Describe roles of upper vs lower esophageal sphincter vs cardiac sphincter
swallows food (it’s made of skeletal muscle), involves oropharynx vs relaxes and opens passage for food vs prevents reflux of stomach contents into esophagus
4 main divisions of stomach; know lesser and greater curvature; know rugae
fundus and body (contain gastric glands), antrum and pylorus (contain pyloric glands that contain G-cells that secrete gastrin to induce parietal cells to release HCl). Lesser = inner curvature, greater = outer curvature. Folds w/in stomach wall
Describe 3 cells produced in stomach
parietal cells release HCl (it converts inactive pepsinogen to active pepsin for hydrolysis of proteins) and intrinsic factor (IF) to scavenge vitamin B-12 and chaperone it to ileum for absorption; chief cells release pepsinogen; mucus cells release mucus to coat stomach and prevent gastric ulcers
Describe biliary tree
- Bile production in liver from cholesterol. 2. bile moves thru common hepatic duct. 3. bile moves thru cystic duct 4. bile hangs out in gallbladder until cholecystokinin (CCK) tells gallbladder to contract bile out 5. bile moves thru common bile duct 6. bile moves to duodenum where bile salts emulsify fats 7. bile moves to ileum where bile salts and fats = absorbed 8. bile salts circulate back to liver and redo the process
What are the functions of the liver?
storage of carbs, fats and proteins, detoxification, bile production via cholesterol, converting ammonia to urea, albumin synthesis, metabolism (ana/catabolism), DESTRUCTION OF ERYTHROCYTES
Name and describe the 3 sections of small intestines vs Name sections of large intestines
duodenum (where most digestion occurs), jejunum (where most absorption occurs), ileum (where important absorption occurs) vs cecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon
Name 3 organs and 1 types of enzyme duodenum involves with
stomach (chyme, HCl), liver/gallbladder (bile salts and pigment), pancreas (enzymes), brush border enzymes (sucrase, lactase, isomaltase, aminonpeptidase and dipeptidase)
Hepatic portal vein vs proper hepatic artery vs hepatic vein vs common hepatic duct; know portal triad
Carries blood containing nutrients and toxins from GI to liver before going to IVC vs supplies arterial O2 rich RBCs from aorta to liver vs takes de-O2 and nutrient poor blood from liver to IVC vs transports bile out of liver
Portal triad: hepatic portal vein, hepatic artery and bile duct
Know hepatic lobules
hepatocytes surrounded by 6 units of portal triads like a hexagon; all blood = collected in central vein to hepatic vein
