1、Animal Nutrition II (Ch. 41),Guest lecturer: Letitia Reichart (Letty),Keywords,Roles of mouth, stomach, sm.&lg. Intestine in digestion Pepsin, pepsinogen Villi, microvilli Cecum Cellulose Cellulase,Acid chyme Enzymatic hydrolysis Peristalsis,Mammalian Digestive System,Alimentary canal Accessory glan
2、ds Salivary glands, pancreas, liver, gallbladder Food moved by peristalsis,Mouth (oral cavity),Mechanical Teeth Saliva Enzymatic Salivary amylase breakdown of starch and glycogen,Throat (pharynx) & Esophagus,Throat junction to esophagus & trachea Epiglottis Esophagus uses peristalsis to move food to
3、 stomach,Stomach,Stores food Secretes gastric juices Acid chyme,Digestive mechanisms in stomach,Mechanical Chemical Enzymatic,Mechanical,Mixing and churning Smooth muscle Every 20 seconds,Chemical,Hydrochloric acid (HCl) pH around 2 Also breaks food down,Enzymatic,Pepsin Breaks down proteins,Chief c
4、ells,Mucus cells,Parietal cells,Interior surface of stomach,Gastric gland,Why doesnt pepsin digest stomach?,Gastric pit,Activation of pepsin,Pepsin (active enzyme),Pepsinogen,HCl,Parietal cell,Chief cell,Stomach,After mechanical and enzymatic digestion:-Acid chyme (nutrient-rich broth) - Pyloric sph
5、incter to the small intestine,Small intestine,Small intestine,Most of:Enzymatic digestion occurs here Absorption of nutrients into the blood stream occurs here,Figure 41.21 p. 859 in Campbell,Stomach,Pancreas,Liver,Gall- bladder,Duodenum of small intestine,Intestinal juice,Bile,Acid chyme,Pancreatic
6、,juice,Figure 41.19 p. 858 in Campbell,Pancreas,Secretes proteases into duodenum,Why doesnt the small intestine digest itself?,Pancreas,Liver,Produces bile that is stored in gallbladder Bile contain bile salts Bile salts aids digestion and absorption of fats,Most nutrient absorption occurs in small
7、intestine,Structure of small intestine,Microvilli,Aid in nutrient transport across epithelial cells of sm. intestine into bloodstream,Large intestine (colon),Major function is to reabsorb water,Here are a few review questions,What would happen if you had a defect in pepsin production?,What would hap
8、pen if you had a defect in pepsin production?,A. carbohydrate would not be digested well B. meat would not be digested at all C. perhaps decreased absorption of protein,What would happen if you had a defect in salivary amylase production?,A. You would die B. You would be unable to digest starch C. T
9、he pH of the stomach would be affected D. None of the above,What would happen if you had a defect in salivary amylase production?,Which of the following would you least like to donate to science while you are still alive?,A. Cecum B. Pancreas C. Reproductive organs,What would happen if you had a def
10、ect in small intestine enteropeptidase?,What would happen if you had a defect in small intestine enteropeptidase?,A. Pancreatic enzymes would not be activated B. Liver enzymes would increased C. Your small intestine would become blocked D. None of the above,Variations of vertebrate digestive system,
11、Herbivorous mammals Specialized fermentation chambers,Coyote vs. Koala,Why does herbivory require specializations?,Plant tissue Harder to break up Contains cellulose Nutrients less concentrated than meat,Structure of cellulose,Only bacteria and protozoa can break down cellulose,Via the enzyme cellulase,Cecum,Pouch at junction between lg and sm intestine Large cecum in rabbits, some rodents, koala, horses Full of symbiotic bacteria,Symbiosis,“living together”,Cecum function,Fermentation chamber Bacteria breakdown cellulose Feces must be reingested,
