Suspension feeders-sift small food particles through water

Clams oystersbaleen whales

Substrate-feeders-live in or on their food

Caterpillars, worms

Fluid-feedersmay 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 anusWastes 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 structuresecrete pepsinogen.

secrete HCl

HCl converts pepsinogen into pepsinAn 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

LACTEAL-part of lymphatic system

-contains fluid called lymph-collects components of fat digestion-will eventually empty into blood vessels

Blood vessels-absorbs amino acids-absorbs monosaccharides-takes nutrient rich blood to liver

Villi

Hepatic Portal system

Largeintestine(colon)

Endof smallintestine

AppendixCecum

Unabsorbedfood material

Anus

Rectum

Smallintestine

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

Fig. 21-13a

Small intestine

Cecum

Stomach

Colon(large intestine)

Carnivore Herbivore