1 / 10

Digestive Systems

Pancreas. Digestive Systems. Accessory organs. Functions of digestive system:. Exocrine gland between stomach and small intestine. Produces several digestive enzymes:. trypsin: digests proteins. pancreatic amylase: digests starches. lipase: digests fats. Also acts as endocrine gland.

kalin
Télécharger la présentation

Digestive Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pancreas Digestive Systems • Accessory organs • Functions of digestive system: • Exocrine gland between stomach and small intestine • Produces several digestive enzymes: • trypsin: digests proteins • pancreatic amylase: digests starches • lipase: digests fats • Also acts as endocrine gland • produces hormones to regulate glucose levels in blood (insulin and glucagon)

  2. Digestive Systems • Accessory organs • Functions of digestive system: • Liver • Large exocrine gland lying above stomach • Produces bile that empties into small intestine : • Bile pigments of old red blood cells eliminated in feces • Bile salts break fats into small droplets (=emulsifies) for lipase

  3. Digestive Systems • Accessory organs • Functions of digestive system: • Liver • Liver also removes toxins, poisons and alcohol from blood • Converts toxic ammonia produced by bacteria in large intestine into urea eliminated in urine • Also regulates levels of many substances produced in body (e.g. steroids hormones)

  4. Gall bladder Digestive Systems • Accessory organs • Functions of digestive system: • Exocrine gland that stores and concentrates bile • Empties directly into small intestine

  5. Digestive Systems • Digestion regulated by neural and hormonal signals • Regulation of digestion: • Nervous system stimulates salivary stomach secretions • When food reaches stomach, hormone gastrin released, which in turn causes release of pepsinogen and HCl

  6. Digestive Systems • negative feedback systems • Regulation of digestion: • Protein present in stomach, gastrin released • Gastrin causes release of pepsinogen and HCl • HCl lowers stomach pH and inhibits release of gastrin

  7. Cholecystokinin (CCK) released if fat in chyme, triggers gall balder to release bile • Secretin released in response to low pH of chyme, stimulate pancreas to release bicarbonate Digestive Systems • Small intestine releases two hormones to regulate digestion • Regulation of digestion:

  8. Digestive Systems • Protein diets are easily digested; carnivores have short digestive tracts • Vertebrate digestive systems vary: • Herbivores require long digestive tracts with specialized organs to digest cellulose in plants • 4-chambered stomach (ruminants) • Large cecum

  9. 4-chambered ruminant stomach Digestive Systems • Herbivore digestive systems: • Plant enters 2 chambers were plants partially digested • Rumen acts as fermentation vat where bacteria and protists break down cellulose • Similar symbiotic relationships occur in termites • ‘cud’ regurgitated and rechewed • ‘cud’ enters final two chambers into which gastric juices released

  10. Non-ruminant herbivores • Cecum enlarged and serves as fermentation vat Digestive Systems • Herbivore digestive systems: • Does not allow for reguritation and rechewing • Improve digestion of plants accomplished by eating feces (= coprophagy)

More Related