1. Evolution of the Circulatory System

2. Open vs Closed System Open Circulatory System Exists in invertebrates
Insects, mollusks some crustaceans
Blood vessel pumps blood through peristalsis to large sinuses where organs are bathed in blood.
Only works in small organisms where cells are close to environment.

3. Insects were huge during the carboniferous period!

4. Open vs Closed Circulatory System
Closed System
Found in some invertebrates and higher order organisms
Blood pumped through closed system of arteries, veins and capillaries
Blood pumped directly to organs
Allows for regulation of blood flow
Increased pressure and speed of blood flow
Allows for larger organisms with cells farther from the environment

5. Evolution of the heart
Hearts can be found in animals with 2, 3 and 4 chambers.

6. 2 Chambered Heart Found in fish One atria and one ventricle
Blood pumped to gills to pick up O2 and then
travels to organs and then back to heart.
Low blood pressure
Single Circulation

7. 3 Chambered Heart Found in reptiles and amphibians
2 atria and 1 ventricle
1 atria deoxygenated blood from body
1 atria oxygenated blood from lungs.
Single ventricle pumps blood out to both
lungs and body.
Oxygenated and deoxygenated blood mixed
In ventricle causing dilute O2 blood.

8. 4 Chamber Heart Birds and mammals 2 atria and 2 ventricles
Oxygenated and deoxygenated blood
kept separate.
Allows for increased blood pressure, thermal regulation and sustained muscle movement.