Suspension feeders sift small food particles through water

Suspension feeders -sift small food particles through water Clams oysters baleen whales

Substrate-feeders -live in or on their food Caterpillars, worms

Fluid-feeders may be parasites that live on the fluid of other organisms -aphids (on phloem sap of plants) -mosquitoes (on blood of mammals) May not be parasites -hummingbirds and insects on nectar

Bulk-feeders -eat large quantity of food -most animals

Digestion occurs in specialized compartments The simplest is the gastrovascular cavity No anus Wastes leave via the mouth

Crop -moisten & store Gizzard -grind Intestine/ceca -absorb

Oral cavity

Bulk-feeders -eat large quantity of food -most animals

Human Digestive System • True digestive structures vs. accessory structures • Mechanical digestion vs. chemical digestion

Digestion begins in the oral cavity: chewing (mechanical digestion) and addition of saliva to food to form a bolus Salivary amylase digests starch and glycogen (chemical digestion) Antibacterial agents pharynx

Involuntary contractions of smooth muscle surrounding the digestive tract propels food Occurs in esophagus and the intestines

Stomach structure secrete pepsinogen. secrete HCl converts pepsinogen into pepsin An adaptation which prevents stomach from digesting itself Mucus cells secrete mucus -lubricates and protects stomach

Helicobacter pylori

Bile emulsifies fat Physically breaks up fat globules Made in Liver Stored in gall bladder Including bicarbonate

Pancreatic enzymes (released into the duodenum via a duct) • • Trypsin (protein digestion) Pancreatic amylase (glycogen/starch) Lipase (fats) Nucleases (nucleic acids)

Intestinal enzymes (from wall of small intestine) • Disaccharidases (maltase, sucrase, lactase) • Dipeptidases

Anatomy of the small intestine

Villi Blood vessels -absorbs amino acids -absorbs monosaccharides -takes nutrient rich blood to liver LACTEAL -part of lymphatic system -contains fluid called lymph -collects components of fat digestion -will eventually empty into blood vessels

Hepatic Portal system

Large intestine (colon) Small intestine End of small intestine Rectum Unabsorbed food material Cecum Appendix Anus

Cecum is blind pouch at the intersection of the small and large intestines In humans it is a vestigial organ called the ? ?

Fig. 21 -13 a Stomach Small intestine Cecum Colon (large intestine) Carnivore Herbivore