1. Ch. 41

2. Need to Feed Animal nutrition Food being taken in, taken apart, and taken up Herbivores Dine mainly on plants Carnivores Dine mainly on other animals Omnivores Regularly dine on animals, plants, and algae Opportunistic Feeders Eat outside normal diet when usual foods are unavailable

3. Essential Nutrients Materials that an animal’s cells require but cannot synthesize Essential Amino Acids Must be obtained from food (8) Essential Fatty Acids Most are synthesized Vitamins Organic molecules that have diverse functions and are required in the diet in very small amounts Water soluble vs. fat soluble Minerals Inorganic nutrients required in small amounts cofactors

4. Essential Nutrients

6. Dietary Deficiencies Diet that lacks one or more essential nutrients or consistently supplies less chemical energy than the body requires Malnourished Failure to obtain adequate nutrition Undernutrition A diet that fails to provide adequate sources of chemical energy Overnourished obesity Assessing Nutritional Needs

7. Ingestion, Digestion, Absorption, Elimination 1.Ingestion –act of eating/feeding 2.Digestion –Food is broken down into molecules small enough for the body to absorb –Mechanical and chemical 3.Absorption –uptake of small molecules from digestion 4.Elimination –undigested material passes out of the digestive compartment

8. Four Main Feeding Mechanisms of Animals Suspension feeders and filter feeders Eat small organisms or food particles suspended in the water –clams, oysters Use a filtering structure to strain food from water –Baleen whale Substrate feeders live on or in their food source leaf miners

9. Feeding Adaptations Deposit feeders substrate feeder that ingests partially decayed organic matter Earthworms Fluid feeders suck nutrient rich fluids from a living host aphids, hummingbirds, bees, leeches, mosquitoes Bulk feeders eat relatively large pieces of food adaptations to kill prey or tear off vegetation

10. Digestive Compartments Intracellular Digestion Hydrolysis of food inside vacuoles Begins with phagocytosis or pinocytosis Food vacuoles organelle that digests its food without hydrolytic enzymes mixing with the cell’s cytoplasm Fuse with lysosomes Sponges

11. Digestive Compartments Extracellular digestion Digestion occurs within compartments that are continuous, with the outside of the body Gastrovascular cavity digestive sac with a single opening; functions in both digestion and nutrient absorption More complex animals have alimentary canals

12. Digestive Compartments Alimentary canal (complete digestive tract) digestive tube running between two openings: mouth and anus organized into compartments for digestion and absorption (increases efficiency) unidirectional passage of food

13. Mammalian Digestion

14. Organs Specialized for Sequential Food Processing Alimentary Canal and Accessory Organs Peristalsis Alternating waves of contraction and relaxation in the smooth muscles lining the canal Sphincters junctions b/w specialized compartments that act like ringlike valves

15. Oral Cavity, Pharynx, Esophagus Oral Cavity Beginning of physical and chemical digestion –chewing –secretions from salivary glands Saliva contains… –mucin, buffers, antibacterial agents, amylase Bolus –chewed food that enters the pharynx

16. Pharynx intersection for both digestive and respiratory systems epiglottis blocks trachea during swallowing Esophagus conducts bolus from pharynx to stomach via peristalsis Oral Cavity, Pharynx, Esophagus

17. Digestion in the Stomach Food storage elastic wall with rugae to hold up to 2L of food Churning contraction of stomach muscles mixed about every 20 minutes; takes 2-6 hours to pass to the small intestine Begins digestion of protein bolus  chyme passes to small intestine through pyloric sphincter

18. Digestion in the Stomach Secretion controlled by the hormone, gastrin mucous cells (secrete mucin & gastrin) chief cells (release pepsinogen or zymogen) parietal cells (secrete HCl & intrinsic factor) HCl + pepsinogen  pepsin (a protease – a protein digesting enzyme)

19. Digestion in the Small Intestine Cholecystokinin Major organ of digestion and absorption Pancreas, liver, gall bladder, and small intestine all contribute to what occurs here Products released into duodenum –1 st part of the small intestine Jejunum and ileum –Villi and microvilli

20. Pancreatic Secretions Exocrine gland Secretes hydrolytic enzymes Produces bicarbonate solution to neutralize stomach acid

21. Bile Production and Secretions by Liver Bile Mixture of substances made in the liver that act as emulsifiers of fat Stored and concentrated in the gall bladder Epithelial lining Source of many digestive enzymes

22. Absorption in the Small Intestine Villi Fingerlike, epithelial projections Microvilli – epithelial projections on each villus cell Hepatic portal vein Blood vessel that leads to directly to the liver Liver regulates distribution of nutrients and allows toxins to be removed

23. Absorption in the Small Intestine Chylomicrons Water soluble fat globules made of triglycerides coated in phospholipids, cholesterol and proteins Lacteal Vessel at the end of each villus Part of lymphatic system

24. Absorption in the Large Intestine Cecum, colon, rectum Appendix is an extension of the cecum lymphoid tissue Water reabsorption Feces moved along by peristalsis Becomes increasingly solid Intestinal bacteria Methane, hydrogen sulfide, vitamin K, biotin, folic acid Two sphincters (one voluntary and one involuntary) control the exiting of the feces

25. Digestive System

27. Dentition

28. Dental Adaptations carnivores: pointed canines & incisors herbivores: broad, ridged surfaces omnivores: unspecialized snakes: fangs

29. Length of tract and diet –herbivores and omnivores have a longer tract b/c cell walls are more difficult to digest Stomach and Intestinal Adaptations

30. Mutualistic Adaptations Symbiotic bacteria and protozoa Produce cellulase Horses: in large cecum Rabbits and some rodents: in cecum and colon –Corophagy (”dung eating”) Ruminants –Deer sheep cattle

31. Regulation of Digestion 1.Gastrin 2.Cholecystokinin and secretin

32. Glucose Homeostasis 1.High blood glucose –insulin 2.Low blood glucose –glucagon

33. Regulation of Appetite and Consumption Ghrelin Triggers feelings of hunger Insulin Suppresses appetite Leptin Suppresses appetite PYY Appetite suppressant; counters ghrelin