The document discusses the process of digestion in animals. It begins by explaining that digestion breaks down important substances like proteins, carbohydrates, fats, and nucleic acids that the body needs. It then covers the differences between plant and animal nutrition, and discusses how digestion provides evidence of evolution. Various aspects of digestion systems are explained, including intracellular and extracellular digestion. The stages of digestion - ingestion, digestion, absorption, and elimination - are outlined. Key organs involved in digestion like the mouth, esophagus, stomach, small intestine, large intestine are described along with their functions. Hormones that regulate digestion are also mentioned.

1. DIGESTION

3. What does the previous slide suggest?

4. Digestion leads to the breakdown of the important substances needed by the body to grow and develop….. Protein Carbohydrates Fats Nucleic acids

5. Why does the plant need to eat a fly when it can undergo photosynthesis?

6. Plant nutrition Plant are producers, they are ________. Animals are _______, they are heterotrophic. Heterotrophs are opportunistic feeders

8. Digestion as an evolutionary evidence Compartmentalization Mode of feeding Mutualistic relationship Also presence of fats, why?

9. Intracellular, extracellular and everything in between….. Intracellular Food vacuoles, amoebocytes Extracellular Incomplete vs complete digestive system

10. Incomplete digestive system bridges….. Differs from complete because…… E.g. gastrovascular cavity of cnidarians Gastrodermis- with specialized digestive cells HYDROLYSIS OF MACROMOLECULES IS INTRACELLULAR

11. Gastrovascular cavity

12. Complete Specialized compartment Exit and entrance are different Extracellular hydrolysis of food Complexity varies

13. Modes of Feeding Suspension feeders Substrate feeders Fluid feeders Bulk feeders

15. Symbiosis is nice….. Evolution of symbiotic relationship with other organisms in processing food … . why is this needed?

16. The four-chambered stomach of cows

17. Four stages of food processing Ingestion Large oral cavity Digestion Mechanical vs chemical Absorption Elimination

19. The oral cavity or in short the mouth What is the mouth for? Why do we need to produce saliva? What is an enzyme and how does it help in the digestion of food?

20. Mechanical Digestion, what is it for?

21. Pharynx Crossroad of food and air Where bolus enters the esophagus Epiglottis- flap that covers the entrance of air when swallowing

22. Epiglottis in action

23. The esophagus Presence of striated and smooth muscle Moves the bolus from pharynx to the stomach peristalsis Presence of goblet cells

24. Peristalsis Wave-like motion responsible for the movement of digested food in the alimentary canal

26. The stomach Storage and digestion of food Sphincters- regulate movement of bolus and chyme Which one has a larger stomach, a carnivore or an herbivore? (pound-for-pound)

27. Still on stomach….. Chief cells vs parietal cells Pepsinogen and HCl follows a positive feedback mechanism

28. Ouch, my stomach hurts…. Rapid mitotic activity Activation of pepsin Goblet cells

29. Ouch, my heart burns!!!! Heart burn is not caused by the devil or your evil exes burning your heart, it is the result of the loosening of the valves

30. Small intestine Main organ of digestion and absorption Why is it the longest? Divided into the duodenum, jejunum, ileum

31. Absorption Villus - folds found in the small intestine Microvillus - microscopic fingerlike projections that increases the absorption of materials Each villus is connected to a capillary (BV) network and lacteals(Lymphatic system)

32. RECITATION ON THE DIGESTION OF THE FOUR MACROMOLECULES Protein Carbohydrates Fats Nucleic acids

33. Hormones that regulate digestion Gastrin-stimulated by gastric juices Inhibited by low pH stimulates secretion of gastric juice Enterogastrones- group of enzymes found in the duodenum Cholecystokinin (CCK)- stimulated by fats and amino acids Stimulates gall bladder to release bile Secretin- stimulated by the acidic chyme Stimulates pancreas to release bicarbonates If chyme is rich in fats, it stimulates the duodenum to release other enzymes to slow down digestion in the stomach

34. Large Intestine Also called the colon Cecum – small pouch that has different fxns Appendix- small cecum found in man Rectum- portion of the large intestine that temporarily stores feces Main fxn of colon is to reabsorb water Feces- waste that was formed after digestion Compactness depends on water that was reabsorbed

35. Large Intestine Intestinal Bacteria- common example is E. coli Have mutualistic relationship with host Generate methane or hydrogen sulfide Some produce vitamins that are needed by the body

36. Nutrition Nutritionally adequate diet composed of: fuel (chemical energy) organic raw materials (carbon skeletons) essential nutrients (substances the animal cannot make)

37. Balancing the fuel Homeostatic mechanism balances the animal’s fuel ATPs that were produced are budgeted depending on the energy requirements Fats have the highest amount of ATP Glucose conversion is an example of homeostatic mechanism

38. Caloric Imbalance Undernourishment Calorie deficiency Overnourishment Excessive calorie intake- results to obesity Malnourishment Deficient in any essential nutrients

39. Essential Nutrients Essential Amino Acids Essential Fatty Acids Vitamins Minerals

40. Essential Amino Acids Tryptophan, methionine, Valine, Threonine, Phenylalanine, Leucine, Isoleucine, Lysine, Histidine (infants) Deficiency in one of these may result into protein deficiency

41. Essential Fatty Acids Essential Fatty Acids belong to the unsaturated fatty acid groups An example is linoleic acid Deficiencies are rare

42. Vitamins Organic molecules that are required relatively in small amount Two types: Water-soluble B vits, C Fat-soluble A, D, E, K

43. Minerals Inorganic nutrients that are required in small amounts E.g. Calcium, Phosphorous, Sodium, etc.

44. Balance diet what enters= what leaves It is easier to take in calories in the body than to burn it The food pyramid serves as a guide in the kind of foods that should be taken in