1. WARM-UP 1. (Ch. 40) What is the principle of countercurrent exchange? 2. (Review) What are the 4 classes of macromolecules? 3. (Ch. 41) You eat a piece of candy. List the structures it passes through as it travels through your alimentary canal. 4. Where does most of the digestion of the candy in #3 happen?

2. Chapter 41: Animal Nutrition

3. What you need to know:  Major compartments of alimentary canal (organs) – and their contributions to animal nutrition.  Digestive glands: salivary, pancreas, liver, gall bladder – and their contributions to animal nutrition.  Digestion of carbs, proteins, fats, nucleic acids.

4. Essential Nutrients: required by cells, obtained through food  Four classes of essential nutrients:  Essential amino acids (8)  Essential fatty acids  Vitamins (13) - fat-soluble, water-soluble  Minerals

7. Dietary Deficiencies  Undernourished: diet is deficient in calories, not enough energy  Malnourishment: missing 1+ essential nutrients Herbivore licks exposed salts and minerals lacking in plants.

8. The main stages of food processing: 1. Ingestion: eating 2. Digestion: breakdown of food into small molecules  Mechanical (chewing, grinding)  Chemical (enzymes) 3. Absorption: cells take up nutrients 4. Elimination: pass undigested materials from digestive system

11. Digestive Compartments  Most animals process food in specialized compartments  Intracellular: digestion of food inside cells by food vacuoles  Ex. phagocytosis, pinocytosis, sponges  Extracellular: food broken down outside of cells  Gastrovascular cavity (simple) or alimentary canal (complex)

12. Intracellular Digestion: Sponges

13. Extracellular Digestion  Compartments are outside of the animal’s body  Gastrovascular cavity: simple animals; single- opening, two-way digestion (food in, waste out) Digestion in a hydra

14.  Alimentary canal: more complex, one-way tubes with mouth and anus

15. Specialized organs for digestion in Humans  Digestive system = alimentary canal + glands  Glands = salivary glands, pancreas, liver, and gallbladder Q: Can you name the organs of the human alimentary canal in order?

17.  Peristalsis: push food through rhythmic contractions of muscles in the wall of the canal  Sphincters: valves regulate the movement of material between compartments Digestion of Macromolecules:  Mouth = carbs  Stomach = proteins  Small Intestine = carbs, proteins, fats, nucleic acids

18.  Oral cavity: mechanical, chemical digestion  Salivary glands: saliva lubricates food  Teeth chew food into smaller particles  Salivary amylase: breakdown glucose polymers  Saliva contains mucus, a viscous mixture of water, salts, cells, and glycoproteins  Pharynx: back of throat  Epiglottis: flap of cartilage, covers trachea when swallowing  Esophagus: food tube (pharynx  stomach) Digestion in the Mouth

20. Digestion in the Stomach  The stomach stores food and secretes gastric juice, which converts a meal to acid chyme  HCl: pH 2, kills bacteria & denatures proteins  Pepsin: enzyme (protease) that hydrolyze proteins into smaller peptides  Pepsinogen (inactive)  pepsin (active) by HCl  Mucus: protects lining of stomach  Gastric ulcers: lesions in the lining, caused mainly by bacterium Heliobacter pylori

22.  SI = major organ of digestion and absorption  Duodenum: first section, digestive juices, major chemical digestion  Digestive juices:  Pancreas: bicarbonate (basic), trypsin & chymotrypsin (proteases); lipase (fats); amylase (carbs); nuclease (DNA, RNA)  Bile: made in liver, stored in gall bladder  Emulsify fats (make smaller droplets) Digestion in the Small Intestine

24. Hormones that coordinate digestion:  Gastrin : produced by stomach,  production of gastric juices  Entrogastrin : produced by SI (duodenum),  peristalsis to allow time for fat digestion  Secretin & CCK (cholesystokinin) : secreted by SI (duodenum),  flow of digestive juices from pancreas & gall bladder

25. Absorption in the Small Intestine  Villi and microvilli increase surface area

26.  Villi  capillaries  hepatic portal vein  liver  heart  Liver: distribute nutrients, detox, glucose storage (glycogen)

27. Absorption in the Large Intestine  LI = colon  Function = compact waste, reabsorb water  Cecum: pouch where SI & LI meet, ferment plant material  Appendix = extension of cecum, role in immunity  Rectum: end of LI, feces stored until elimination

28. Evolutionary adaptations of vertebrate digestive systems correlate with diet  Dentition: teeth correlate with diet  Herbivores: longer alimentary canal, longer cecum

29. Mutualistic Adaptations  Many herbivores have fermentation chambers, where mutualistic microorganisms digest cellulose (ruminants)

30. Homeostatic Mechanisms  Vertebrates store excess calories as glycogen in the liver and muscle cells, and as fat in adipose tissue  Overnourishment can lead to obesity  Leptin: hormone, suppresses appetite

31. Glucose Homeostasis