1. Chapter 41 Animal Nutrition By: Ashley Kelch, Melanie Diaz, Joy Chao

2. Overview: The Need to Feed Three types of feeders: Herbivores, Carnivores, and Omnivores Three nutritional needs: –Fuel (chemical energy): For cellular work of the body –Organic raw material: For biosynthesis –Essential nutrients: Like vitamins (animals cannot make for themselves)

3. Four feeding mechanisms Suspension feeder: Sift particles in water (ex. whale) Substrate feeder: Live on food source (ex. fly larvae)

4. Feeding mechanisms (cont.) Fluid feeder: Suck nutrient-rich liquid from host (ex. mosquito) Bulk feeder: Eat relatively large piece of food (ex. python)

5. Glucose Regulation Surplus of calories stored as glycogen in liver and muscle cells When glycogen depots are full, calories stored as fat When glycogen needed, taken from depot and oxidized

6. Caloric Imbalance Undernourishment is when an animal is in chronic deficit of calories Overnourishment, or obesity, contributes to diabetes, colon and breast cancer, and cardiovascular disease

7. Obesity and Evolution Natural selection can sometimes favor individuals able to obtain fatty foods –Petrel parents often bring their chicks food rich in lipid so the chicks can survive if the parents go hunting far distances

8. Essential Nutrients Malnourished: lacking one or more essential nutrients (Undernourished: lacking in calories) Four essential nutrients: Essential amino acids, Essential fatty acids, Vitamins, and Minerals

9. Essential amino acids Most common type of malnutrition: protein deficiency Reliable source of essential nutrients: meat, egg, cheese, and other animal products Animal products: “Complete”, has all the essential amino acids in proper proportions Plant products: “Incomplete”, products are deficit in one or more essential amino acid

10. Essential fatty acids and Vitamins Essential fatty acids –Animals can synthesize most fatty acids, but need to obtain some unsaturated fatty acids. –Used to make phospholipid in membrane Vitamins –Small amount needed –Split in to water-soluble and fat-soluble –Water-soluble: includes B complex (coenzyme), vitamin C (production of connective tissues) –Fat-soluble: Vitamin A (pigment of the eye), D (calcium absorption), E (antioxidant), and K (blood clotting)

11. Minerals –Calcium, Phosphorus: construct and maintains bones –Iron: component of cytochrome, which is used in cellular respiration –Magnesium, iron, zinc, copper, manganese, selenium, and molybdenium: cofactors of enzymes –Sodium, potassium, and chlorine: nerve functions

12. Food Processing First stage is Ingestion - the act of eating Second stage is Digestion - breaking down of food into molecules small enough for the body to absorb Third stage is Absorption - animal’s cells take up small molecules from digestive compartments Fourth stage is Elimination - undigested material passes out of the digestive compartment

14. Digestive Compartments These are specialized compartments that help the animal digest food, but not their own tissue Intracellular digestion is when the digestion takes place inside of the cell: food vacuoles Extracellular digestion is when digestion takes place outside of the cell: gastrovascular cavity (pouch) allows for digestion of larger prey Complete digestive tract (alimentary canal): a digestive tube with two openings, which carries the food in one direction

16. Human Digestive System Digestion begins in mouth where saliva is produced to make food easier to swallow The tongue then manipulates the food into a bolus and pushes into the pharynx (throat) The epiglottis then moves to cover the windpipe so that the food is guided into the esophagus The esophagus pushes food to the stomach by peristalsis (rhythmic waves of contraction)

18. Human Digestive System cont. The stomach can store food and has important digestive functions It secretes gastric juices which are mixed with the food by the churning of the stomach muscles These juices contain hydrochloric acid, which disrupts the extracellular matrix that binds together the cells in the food, and pepsin, which breaks peptide bonds, cleaving them into smaller polypeptides to later be digested further by the small intestine After the food has been sufficiently mixed with gastric juices it becomes acid chyme, a nutrient- rich broth, which is slowly passed to the intestine

19. The Small Intestine The small intestine is the longest section of the alimentary canal Acid chyme from the stomach and digestive juices from the pancreas, liver, and gallbladder mix together in the first 25cm of the small intestine in a section called the duodenum The Liver produces bile which helps the body digest and absorb fats The Gallbladder stores the bile made in the liver until it is needed The Pancreas produces several hydrolytic enzymes and a solution rich in bicarbonate that as a buffer to offset the acidity of chyme coming from the stomach

20. Small Intestine (cont.)

21. Most of the absorption of nutrients in the alimentary canal takes place in the small intestine The adaptation of folds, villi, and micro villi greatly increase the surface area for maximum absorption inside the small intestine

22. Small Intestine (cont.) Penetrating the core of each villus is a net of microscopic blood vessels and a small vessel of the lymphatic system Nutrients are absorbed across the epithelial (intestinal) cells on the outside of each villus

23. Small Intestine (cont.) Some simple sugars are diffused across the epithelial cells, but most nutrients (amino acids, small peptides, vitamins, glucose, and several other simple sugars) are pumped across the membranes

24. The Large Intestine The colon (large intestine) helps to recover water that has entered the alimentary canal by absorbing it back into the body. Some of the bacteria produce essential vitamins, including biotin, folic acid, vitamin K, and several B vitamins. These vitamins, absorbed into the blood, supplement our dietary intake of vitamins.

25. Evolutionary Adaptations Mammals have developed adaptations in their digestive systems specialized for their diet. Many species of bacteria live in the small intestine of herbivores to help break down nutrients in plant material that their bodies have trouble digesting.

26. Evolutionary Adaptations (cont.)