BIO 181 1st Edition Lecture 20 Past LectureI. DigestionII. Four Chamber of the Ruminant StomachCurrent LectureI. Monogastric AnimalsII. The Human Digestive System III. Bird Digestion I. Monogastric Animalsa. Five Overall Tasks of a Complete Digestive System • b. Mechanical processing and motility – physical manipulation thatbreaks up, mixes & propels food c. Secretion – Release of digestive enzymes & other substances from lining of tract and accessory organs d. Digestion – chemical breakdown of food into molecules small enough to be absorbede. Absorption – Passage of digested nutrients & fluid across the tube wall and into body fluids f. Elimination – Expulsion of undigested, unabsorbed residues from the end of the gutII. The Human Digestive System a. a muscular tube extending from mouth to anusi. Major Components1. Mouth - oral cavity2. pharynx- throat3. esophagus4. guta. stomachb. small intestine, 4 hours from mouth through small intestinec. large intestined. rectume. AnusThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Accessory organs1. salivary glands: secrete saliva, which has enzymes,mucus, buffers2. liver: secretes bile, for emulsifying fat3. gall bladder: stores & concentrates bile 4. pancreas: does a lot of jobs1) secretes digestive enzymes that break down all major food molecules, 2)Secretes buffers against HCL from stomach, 3)Secretes insulin to control glucose metabolismb. Mechanical Digestioni. starts in the mouth 1. The teeth break up food2. saliva moistens it a. almost half a gallon of saliva produce everydayb. Amylase which is a salivary enzymes begin thedigestion of starch c. bicarbonated. mucus, which bind food into boluse. saliva is 99% water3. The tongue pushes the bolus of food into the pharynxii. Swallowing 1. Complex reflex 2. Tongue forces food (voluntary action) into pharynx, common chamber for food and air 3. Epiglottis closes off trachea; breathing temporarily ceases4. Once food is taken in by the pharynx then it goes into the pharyngeal stage and goes into5. Esophagus and becomes involuntary, wave like contraction known as peristalsis.iii. Entry is managed by sphincters 1. controls entry and exit into stomachiv. Mixing of ingested food is still mechanical processesc. Digestion of proteins and acids is chemical digestion.i. Pepsin only enzyme active within the stomachii. Bicarbonate-neutralizes stomach acid, bile produced by the liver, which breaks down fatiii. -Liver largest solid gland in human bodyd. detoxifies stuff like alcohol,drugs from livere. large reservoir of bloodf. -fatty liver due to intoxicationg. cystic duct only unique to liver and sends bile to gallbladderh. parts of small intestine’i. ~25 ft. longii. most chemical digestion and nutrient absorption hereiii. Receives digested food called “chyme” from stomachiv. Receives secretions from liver, gallbladder, and pancreas1. duodenum- first part of small intestinea. common bile duct sends bile straight to the here2. Jejunum- covered in mucosa, called villi, which increase the surface area of tissue available to absorb nutrients from ingested foodstuffs3. Ileum- last part of the small intestinea. redouble for digestion, longest part, which soles for extension about’b. region of small intestine is about 20ft by itselfi. Large intestinei. E. Coli lives in our large intestineii. Three main parts of large intestine1. cecum-chyme from smalla. vestigial organ in our bodyb. appendix2. colon-longest portiona. water is absorbed hereb. bacterial activity may produce hydrogen sulfidec. produces odor of feces, flatus (gas) due to bacterial action on undigested plant polysaccharides 3. rectum- where undigested food goes4. peristaltic contractions force feces into it from colon; triggers defecation reflex, released from anusa. Colon cancer prevented by fiber and exerciseIII. Bird Digestion a. Birds-don't have teeth because it would be heavy during flightb. Crop- Stores and softens food, is a dilation of the esophagusc. Gizzard-extra chamber that crushes the food. i. contains gravel and grit that aids in crushing and in their digestiond. Stomach releases chyme into the duodenum to small intestinee. they have no bladder or