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Digestion2.

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Digestion2.

  1. 2. Digestion <ul><li>All animals are heterotrophs </li></ul><ul><li>Different modes of feeding evolved </li></ul><ul><li>Modes of feeding (structure-function) can be used as an evolutionary evidence </li></ul><ul><li>Compartmentalization </li></ul>
  2. 4. Intracellular vs. Extracellular <ul><li>Intracellular- occurs within food vacuoles </li></ul><ul><ul><li>E.g. food vacuoles in Paramecium , amoebocytes of sponge </li></ul></ul><ul><li>Extracellular- occurs within specialized compartments </li></ul><ul><ul><li>Incomplete vs. complete </li></ul></ul>
  3. 5. Incomplete <ul><li>A single opening is present for both entrance of food and exit of wastes </li></ul><ul><li>Gastrovascular cavity of Cnidarians </li></ul><ul><li>Gastrodermis- has specialized cells that secrete digestive enzymes </li></ul><ul><li>Hydrolysis of macromolecules is intracellular </li></ul>
  4. 6. Incomplete Obelia sp.
  5. 7. Complete <ul><li>Opening of food is different from exit of waste materials </li></ul><ul><li>Specialized regions of the alimentary canal </li></ul><ul><li>Complexity varies in each phylum </li></ul><ul><li>Extracellular hydrolysis of food </li></ul>
  6. 8. Complete Bos taurus
  7. 9. Modes of feeding <ul><li>Herbivore </li></ul><ul><li>Carnivore </li></ul><ul><li>Omnivore </li></ul><ul><ul><li>Dentition </li></ul></ul><ul><ul><li>Alimentary canal </li></ul></ul>
  8. 10. Modes of Feeding <ul><li>Suspension feeders </li></ul><ul><li>Substrate feeders </li></ul><ul><li>Fluid feeders </li></ul><ul><li>Bulk feeders </li></ul>
  9. 11. Modes of Feeding
  10. 12. Symbiotic Relationship <ul><li>Vertebrates acquired symbiotic relationship with microscopic organisms in processing food </li></ul><ul><ul><ul><li>E.g. Ruminants, Humans, termites </li></ul></ul></ul>
  11. 13. Four Main Stages of Food Processing <ul><li>Ingestion </li></ul><ul><ul><li>Large oral cavity </li></ul></ul><ul><li>Digestion </li></ul><ul><ul><li>Mechanical vs. Chemical </li></ul></ul><ul><li>Absorption </li></ul><ul><li>Elimination </li></ul>
  12. 14. Digestion in Humans <ul><li>Primary organs of digestion </li></ul><ul><ul><li>Mouth, pharynx, esophagus, stomach, small intestine, large intestine </li></ul></ul><ul><li>Accessory glands of digestion </li></ul><ul><ul><li>Salivary glands, pancreas, liver, gall bladder </li></ul></ul>
  13. 15. Digestion in Humans <ul><li>Mouth- functions: ingestion and digestion </li></ul><ul><li>Digestion begins in the Oral Cavity </li></ul><ul><ul><li>Mechanical and Chemical digestion </li></ul></ul><ul><ul><li>Salivary amylase- breaks down polysaccharide and glycogen </li></ul></ul><ul><ul><li>Saliva- also fxns as antibacterial agent and neutralizes acidity of foods </li></ul></ul>
  14. 16. Pharynx <ul><li>Upper portion of the throat </li></ul><ul><li>Where air and digested food meet </li></ul><ul><li>Digested ball (bolus) of food enters </li></ul><ul><li>Epiglottis- acts as a seal to prevent food from entering the air passages </li></ul>
  15. 17. Esophagus <ul><li>Upper portion- striated muscle </li></ul><ul><li>Lower portion- smooth muscle </li></ul><ul><li>Connects the pharynx to the stomach </li></ul><ul><li>Peristalsis </li></ul><ul><li>Goblet cells- specialized cells that lines the esophagus </li></ul><ul><ul><li>Release mucus that covers the bolus </li></ul></ul>
  16. 18. Peristalsis <ul><li>Wave-like motion responsible for the movement of digested food in the alimentary canal </li></ul>
  17. 19. Stomach <ul><li>Stores and digests food </li></ul><ul><li>Cardiac sphincter- prevents backflow </li></ul><ul><li>Pyloric sphincter- regulates entrance of acidic chyme to the small intestine </li></ul><ul><li>Secretes digestive juice </li></ul><ul><ul><li>Mixed with food through churning of the stomach through smooth muscle contractions </li></ul></ul>
  18. 20. Stomach <ul><li>Chief cells- secretes pepsinogen </li></ul><ul><li>Parietal cells- secrete HCl </li></ul><ul><li>HCl- disrupts the extracellular matrix of plant and animal cell </li></ul><ul><li>Pepsin- active form of pepsinogen </li></ul><ul><ul><li>Hydrolyzes proteins </li></ul></ul><ul><ul><li>Works best in an acidic environment </li></ul></ul>
  19. 21. Stomach <ul><li>Stomach lining is protected </li></ul><ul><ul><li>First, pepsinogen is only activated when secreted into the lumen due to the action of the acidic HCl (pepsinogen activation-positive feedback) </li></ul></ul><ul><ul><li>Secondly, presence of goblet cells that secrete mucus </li></ul></ul><ul><li>product- acid chyme </li></ul>
  20. 22. Stomach
  21. 23. Small Intestine <ul><li>Major organ of digestion and absorption </li></ul><ul><li>Longest section of the alimentary canal </li></ul><ul><li>Divided into three sections:duodenum, jejunum, ileum </li></ul><ul><li>Duodenum- site of mixing of acidic chyme and other digestive juices (digestion) </li></ul><ul><li>Jejunum and Ileum- absorption </li></ul>
  22. 24. Small Intestine <ul><li>Carbohydrate digestion </li></ul><ul><li>Protein Digestion </li></ul><ul><li>Nucleic Acid Digestion </li></ul><ul><li>Fatty Acid Digestion </li></ul>
  23. 25. Carbohydrate digestion <ul><li>Starch, glycogen and other polysaccharides that were digested in the mouth is further digested </li></ul><ul><li>Pancreatic amylase </li></ul><ul><li>Maltase- splits maltose into its glucose units </li></ul><ul><li>Disaccharides- absorbed by intestinal epithelium </li></ul>
  24. 26. Protein digestion <ul><li>Trypsin and Chymotrypsin- breakdown large polypeptide chain like pepsin </li></ul><ul><li>Dipeptidase- split small peptides </li></ul><ul><li>Carboxypeptidase- breakdown polypeptides in its carboxyl end </li></ul><ul><li>Aminopeptidase- breakdown peptidase in its nitrogenous end </li></ul><ul><li>Enteropeptidase- activates pancreatic enzymes </li></ul>
  25. 27. Protein digestion <ul><li>Intestinal enzymes- aminopeptidase, enteropeptidase </li></ul><ul><li>Pancreatic enzymes- Trypsinogen, Procarboxypeptidase, Chymotrypsinogen </li></ul><ul><ul><li>Enteropeptidase- activates Trypsinogen </li></ul></ul><ul><ul><li>Trypsin- activates Procarboxypeptidase, Chymotrypsinogen </li></ul></ul>
  26. 28. Nucleic Acid Digestion <ul><li>Nucleases- hydrolyze nucleic acids </li></ul><ul><li>Exonucleases- hydrolyze nucleic acids on its terminal </li></ul><ul><li>Endonucleases- hydrolyze nucleic acids within </li></ul><ul><li>Other enzymes hydrolyze the nucleotides into its components </li></ul>
  27. 29. Fatty acid digestion <ul><li>Bile salts- emulsify undigested fats in the duodenum </li></ul><ul><ul><li>Emulsification- inc SA of fat molecules </li></ul></ul><ul><li>Lipase- digests fat molecules </li></ul>
  28. 30. Absorption <ul><li>Villus - folds found in the small intestine </li></ul><ul><li>Microvillus - microscopic fingerlike projections that increases the absorption of materials </li></ul><ul><li>Each villus is connected to a capillary (BV) network and lacteals(Lymphatic system) </li></ul>
  29. 31. Transport of nutrients <ul><li>Passive Diffusion </li></ul><ul><li>Active transport </li></ul><ul><ul><li>Nutrients that were absorbed are transformed into what the body needs </li></ul></ul><ul><ul><li>Chylomicron- small globule that is a combination of fats, cholesterol, coated with proteins </li></ul></ul>
  30. 32. Hormones that regulate digestion <ul><li>Gastrin-stimulated by gastric juices </li></ul><ul><ul><li>Inhibited by low pH </li></ul></ul><ul><ul><li>stimulates secretion of gastric juice </li></ul></ul><ul><li>Enterogastrones- group of enzymes found in the duodenum </li></ul><ul><li>Cholecystokinin (CCK)- stimulated by fats and amino acids </li></ul><ul><ul><li>Stimulates gall bladder to release bile </li></ul></ul><ul><li>Secretin- stimulated by the acidic chyme </li></ul><ul><ul><li>Stimulates pancreas to release bicarbonates </li></ul></ul><ul><ul><li>If chyme is rich in fats, it stimulates the duodenum to release other enzymes to slows down digestion in the stomach </li></ul></ul>
  31. 33. Large Intestine <ul><li>Also called the colon </li></ul><ul><li>Cecum – small pouch that has different fxns </li></ul><ul><li>Appendix- small cecum found in man </li></ul><ul><li>Rectum- portion of the large intestine that temporarily stores feces </li></ul><ul><li>Main fxn of colon is to reabsorb water </li></ul><ul><li>Feces- waste that was formed after digestion </li></ul><ul><ul><ul><li>Compactness depends on water that was reabsorbed </li></ul></ul></ul>
  32. 34. Large Intestine <ul><li>Intestinal Bacteria- common example is E. coli </li></ul><ul><li>Have mutualistic relationship with host </li></ul><ul><li>Generate methane or hydrogen sulfide </li></ul><ul><li>Some produce vitamins that are needed by the body </li></ul>
  33. 35. Nutrition <ul><li>Nutritionally adequate diet </li></ul><ul><ul><li>composed of: </li></ul></ul><ul><ul><ul><li>fuel (chemical energy) </li></ul></ul></ul><ul><ul><ul><li>organic raw materials (carbon skeletons) </li></ul></ul></ul><ul><ul><ul><li>essential nutrients (substances the animal cannot make) </li></ul></ul></ul>
  34. 36. Balancing the fuel <ul><li>Homeostatic mechanism balances the animal’s fuel </li></ul><ul><li>ATPs that were produced are budgeted depending on the energy requirements </li></ul><ul><li>Fats have the highest amount of ATP </li></ul><ul><li>Glucose conversion is an example of homeostatic mechanism </li></ul>
  35. 37. Caloric Imbalance <ul><li>Undernourishment </li></ul><ul><ul><li>Calorie deficiency </li></ul></ul><ul><li>Overnourishment </li></ul><ul><ul><li>Excessive calorie intake- results to obesity </li></ul></ul><ul><li>Malnourishment </li></ul><ul><ul><li>Deficient in any essential nutrients </li></ul></ul>
  36. 38. Essential Nutrients <ul><li>Essential Amino Acids </li></ul><ul><li>Essential Fatty Acids </li></ul><ul><li>Vitamins </li></ul><ul><li>Minerals </li></ul>
  37. 39. Essential Amino Acids <ul><li>Tryptophan, methionine, Valine, Threonine, Phenylalanine, Leucine, Isoleucine, Lysine, Histidine (infants) </li></ul><ul><li>Deficiency in one of these may </li></ul><ul><li>result into protein deficiency </li></ul>
  38. 40. Essential Fatty Acids <ul><li>Essential Fatty Acids belong to the unsaturated fatty acid groups </li></ul><ul><li>An example is linoleic acid </li></ul><ul><li>Deficiencies are rare </li></ul>
  39. 41. Vitamins <ul><li>Organic molecules that are required relatively in small amount </li></ul><ul><li>Two types: </li></ul><ul><ul><li>Water-soluble </li></ul></ul><ul><ul><ul><li>B vits, C </li></ul></ul></ul><ul><ul><li>Fat-soluble </li></ul></ul><ul><ul><ul><li>A, D, E, K </li></ul></ul></ul>
  40. 42. Minerals <ul><li>Inorganic nutrients that are required in small amounts </li></ul><ul><li>E.g. Calcium, Phosphorous, Sodium, etc. </li></ul>
  41. 43. Balance diet <ul><li>what enters= what leaves </li></ul><ul><li>It is easier to take in calories in the body than to burn it </li></ul><ul><li>The food pyramid serves </li></ul><ul><li>as a guide in the kind </li></ul><ul><li>of foods that should be </li></ul><ul><li>taken in </li></ul>

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