| Term | Definition |
|---|
| Mixing waves | Gentle, ripping, peristalic movements that pass over the stomach every 15 to 25 seconds; softens and mixes food with gastric secretions to form chyme |
| Chyme | A soupy liquid formed when the bolus is mix with gastric juices in the stomach |
| pH of stomach | 2.0; most acidic part of the body; pepsin is ineffective at a higher pH |
| Hydrochloric acid | Secreted by parietal cells; net effect of secretion of hydrogen ions and chloride ions seperately into the stomach lumen; kills microbes, denatures protein, and activates pepsinogen into pepsin |
| Gastrin | Stimulates parietal cells to secrete HCl and chief cells to secrete pepsinogen |
| Intrinsic factor | Needed for B12 absorption, which is used in red blood cell formation |
| Mucous | Forms a protective barrier that prevents digestion of the stomach wall |
| Gastric lipase | Splits the short chain triglycerides in fat molecules (milk) into fatty acids and monoglycerides; has a limited role in adult stomachs; pH of 5-6, thus an infants stomach would be less acidic |
| Pepsinogen | Secreted inactively by chief cells; activated by HCl to become pepsin, which breaks down proteins into peptides |
| Gastric juice | Blend of al stomach chemicals, controlled in 3 stages; cephalic, gastric, and instestinal |
| Cephalic stage | Stage of digestion where smell, sight, thought, or initial taste of food activates neural centers in the hypothalamus; stimuli that arouse digestion are relayed to the hypothalamus, which, in turn, initiates nerve impulses in the parasympathetic vagus nerve; these impulses promote peristalsis and secretion of gastric juice (via M.O) |
| Gastric stage | Stage of digestion that starts at the arrival of food in the stomach; gastric juice is controlled by nervous system and hormones; food stimulates stimulates stretch receptors in the walls; chemoreceptors in the stomach monitor pH of chyme; both receptors activate parasympathetic nerves that cause production of gastric juice |
| Hormonal regulation | Release of gastrin from the G cells in response to distention of the stomach and increased pH due to the presence of food; gastrin, released from parasympathetic neurons, stimulates digestive organs to secrete gastric juice, increase motility of the stomach, and promote stomach emptying |
Combine with other sets
Share on Facebook
Share on MySpace