The Frog: circulatory system

1. The Frog: circulatory system • Frogs have a closed circulatory system that is broken into two loops: • 1. Pulmonary circulation: blood is pumped from the heart to the lungs & back to the heart • 2. Systemic circulation: blood is pumped from the heart to the rest of the body & back again

2. The heart has three chambers: two atria & one ventricle

3. The Frog: respiration • Larval amphibians breathe through their gills & skin • As frogs mature, the gills are lost & respiration occurs through the skin & lungs • Respiration through the lungs is called pulmonary respiration • Respiration though the skin is called cutaneous respiration

4. The Frog: Digestive system • Food is captured by a sticky tongue & taken into the mouth • It is then swallowed & moves through the pharynx & elastic esophagus to the stomach • Once in the stomach, gastric digestive juices are secreted by glands that line the stomach

5. A muscle at the base of the stomach opens & allows the food to move into the first section of the intestines: the duodenum • From the duodenum it moves to the ileum where the nutrients released from the food is absorbed into the bloodstream • The duodenum and the ileum make up the small intestine

6. The indigestible parts of the food move into the large intestine where any extra water is reabsorbed & the leftover waste is pushed into the cloaca & out through the vent • The intestines are held in place by a thin but strong membrane called the mesentery

7. The frog has many accessory glands like humans that aid the digestion process • Liver: produces bile which breaks down fat • Gallbladder: bile is stored here until it is needed • Pancreas: secretes enzymes that help further digest the food

8. The Frog: Excretory system • The kidneys are the primary excretory organs • They lie on either side of the lower spinal column against the dorsal body wall • The kidneys filter wastes from the blood & excretes it from the body as urine

9. The Frog: Nervous system • The brain consists of the following parts: • Olfactory lobe: center for the sense of smell & is found at the anterior of the brain • Cerebrum: regulates behavior & learning & is found behind the olfactory lobe • Optic lobe: center for the sense of sight & lies behind the cerebrum

10. Cerebellum: coordinates muscular movement • Medulla oblongata: found at the posterior of the brain & controls organ functions

11. Frog & Toad Myths • They will NOT give you warts! • Their urine is NOT toxic! • If you kiss frogs, they will NOT turn into princes!! (sorry girls)

12. Froggy Facts • Because frogs come out in the rain people used to think that they fell to earth in the rain and in the 1800’s people tried to prove it by catching them! • At first it was thought that frogs could not throw up, but then it was discovered on a space mission that a frog can throw up. The frog throws up its stomach first, so the stomach is dangling out of its mouth. The frog then uses its forearms to dig out all of the stomach's contents and then swallows the stomach back down again. (GROSS!)

13. The End “It’s Not Easy Being Green” -Kermit