process of contraction and relaxation of circular smooth muscles which pushes food thru the alimentary canal
what keeps food from going down into your larynx?
1)the soft palate rises up and closes off nasal cavity
2)larynx rises & epiglottis lowers to seal off larynx
what are the tunics that are contained in most of the alimentary canal?
serosa, muscularis, submucosa, mucosa. stomach has an extra layer oblique muscularis
why doesn't gastric juice in stomach hurt stomach lining?
gastric glands produce mucus which coats stomach lining and protects it from its own gastric juices
what are the effects of the hormone gastrin?
increases lower esophageal sphincter tone
decreases pyloric sphincter tone
increases rate of secretion from gastric pits
increases rate of mixing waves of stomach
what are the 3 regions of the small intestine?
duodenum, jejunum, ileum
duodenum is the smallest portion
what features in intestine increase the rate at which nutrients are absorbed?
circular folds and intestinal villi covered w/microvilli
what are the 3 main hormones released by small intestine?
secretin, cholecytokinin (CCK), Gastric Inhibitory Peptide (GIP)
what is the effect of secretin?
reduces gastric juice from production & increases secretion of acid-neutralizing juice from pancreas which increases ph of chyme
why can't a cell produce an active enzyme which breaks down proteins?
cause producing an active protein-digesting enzyme would kill the cell
what functions do the bacteria in the large intestine perform?
produce vitamin K, biotin, folic acid
why do people feel they need to defecate shortly after eating?
the act of filling the stomach triggers mass movements which rapidly move chyme towards rectum
what travels from the portal triads to the central vein in a liver lobule? what flows the opposite way?
blood travels from portal triad to the central vein. bile flows the opposite way
is bile a digestive enzyme? what does it do?
bile is NOT a digestive enzyme. it emulsifies fats, making them easier to digest
what 4 secretions are designed to reduce acidity in alimentary canal?
1. alkaline mucus from duodenenal glands 2. intestinal juice from intestinal glands 3. bile from gallbladder 4. bicarbonate in pancreatic juice