1. Digestion: Obtaining & Processing Food Herbivores = plant-eaters Herbivores = plant-eaters Carnivores = meat-eaters Carnivores = meat-eaters Omnivores = both plants and other animals Omnivores = both plants and other animals

2. Digestion: Obtaining Food Solid foods Filtering from water substrate feeders fluid feeders

3. Digestion: 4 Stages

4. Digestion Mechanical Breakdown: Mechanical Breakdown: Physically breaking food apart (teeth, tongue, stomach, etc) Physically breaking food apart (teeth, tongue, stomach, etc) Chemical Breakdown: Chemical Breakdown: enzymes and secretions to break down chemically enzymes and secretions to break down chemically

5. Digestion: Chemical Breakdown

6. Digestion: Protozoans Intracellular digestion with oral groove or phagocytosis Intracellular digestion with oral groove or phagocytosis

7. Digestion Gastrovascular cavity vs specialized digestive tract Gastrovascular cavity vs specialized digestive tract Gastrovascular cavity: one opening Gastrovascular cavity: one opening cnidarian & flatworms cnidarian & flatworms

8. Digestion: Alimentary Canal Most have alimentary canal Most have alimentary canal Tube running from mouth to anus Tube running from mouth to anus divided into specialized regions that process food sequentially divided into specialized regions that process food sequentially Crop: stores food Crop: stores food Gizzard: grinds food (especially if no jaws or teeth) Gizzard: grinds food (especially if no jaws or teeth)

9. Digestion: Human Alimentary Canal vs Accessory Organs Alimentary Canal vs Accessory Organs

10. Digestion: Human Alimentary Canal Alimentary Canal mouth, esophagus, stomach, small intestines, large intestines, rectum, anus Accessory Organs Accessory Organs salivary glands, liver, gall bladder, pancreas

11. Digestion: Mouth Mechanical Digestion Mechanical Digestion Teeth, tongue Teeth, tongue Chemical Digestion Chemical Digestion Saliva moistens it Saliva moistens it Salivary enzymes amylase begin breakdown of starch Salivary enzymes amylase begin breakdown of starch Tongue pushes the chewed food into the pharynx Tongue pushes the chewed food into the pharynx

12. Digestion: Esophagus Peristalsis: muscle contractions pushing down bolus (food) Peristalsis: muscle contractions pushing down bolus (food)

13. Digestion: Stomach

14. Stomach mixes food with gastric juice from gastric glands Stomach mixes food with gastric juice from gastric glands Gastric glands – make HCl, pepsinogen, mucous Gastric glands – make HCl, pepsinogen, mucous HCl activates pepsinogen (inactive enzyme) to form pepsin (enzyme to breakdown protein) HCl activates pepsinogen (inactive enzyme) to form pepsin (enzyme to breakdown protein) HCl also kills germs HCl also kills germs Mucous – lines & protects stomach walls Mucous – lines & protects stomach walls Chyme (partially digested food) enters duodenum (beginning of small intestines via pyloric sphincter Chyme (partially digested food) enters duodenum (beginning of small intestines via pyloric sphincter

15. Digestion: Small Intestines

16. Digestion: Small Intestine / Pancreas / Liver / Gall Bladder Most of chemical digestion and absorption take place in small intestines Most of chemical digestion and absorption take place in small intestines Pancreas Pancreas Makes bicarbonate (HCO 3 - ), base that neutralizes stomach acid Makes bicarbonate (HCO 3 - ), base that neutralizes stomach acid Pancreatic enzymes digest polysaccharides, proteins, nucleic acids, and fats Pancreatic enzymes digest polysaccharides, proteins, nucleic acids, and fats Bile (made in liver, stored in gall bladder) emulsifies (mechanical breakdown) fat droplets for attack by pancreatic lipase Bile (made in liver, stored in gall bladder) emulsifies (mechanical breakdown) fat droplets for attack by pancreatic lipase Trypsin breaks down protein in base environment Trypsin breaks down protein in base environment

17. Digestion: Small Intestine Absorption by villi Absorption by villi

18. Digestion: Large Intestines Absorption of water Absorption of water E Coli live in LI, make Vitamin K E Coli live in LI, make Vitamin K Undigested material = feces Undigested material = feces

19. Digestion: Evolutionary Adaptations Plant harder to digest than meat because of cellulose Plant harder to digest than meat because of cellulose Herbivores have longer digestive tract Herbivores have longer digestive tract

20. Digestion Cows have 4 stomach chambers to break down cellulose Cows have 4 stomach chambers to break down cellulose