1. Biology 201 Dr. Edwin DeMont St. Francis Xavier University Respiration

2. St. Francis Xavier University Gas Exchange Animals must supply the oxygen required for aerobic respiration and a remove the carbon dioxide. The process of gas exchange is called respiration. Five main types of respiratory systems exist in animals: 1.Diffusion across plasma membranes (I) 2.Tracheae (I) 3.Cutaneous (body surface) exchange (I) 4.Gills (I,V) (I: Invertebrates) 5.Lungs (I,V) (V: Vertebrates)

3. St. Francis Xavier University Diffusion (I) Protozoa Cnidarian Flatworm Diffusion across plasma membranes Cutaneous (body surface) exchange

4. St. Francis Xavier University Tracheal System (I) Tracheae are an internal system of branching tubes that brings air directly to each cell in the body. Video

5. St. Francis Xavier University Book Lung (I) Tarantula Book lungs are sheets of internal lamellae that are exposed to air on the outside and filled with blood on the inside.

6. St. Francis Xavier University Gills (I) Bivalve Gills are very efficient in aquatic ecosystems— gills evolved from large or small skin projections with blood inside of the projections.

7. St. Francis Xavier University Gills (V) Gills may be internal or external, but gas exchange (oxygen in and carbon dioxide out) is very efficient due to countercurrent flow.

8. St. Francis Xavier University Lungs: Birds Lungs of birds are a flow-through system wherein air is conducted through the lungs in a single direction, and avian lungs are particularly efficient (90% of oxygen in air is removed).

9. St. Francis Xavier University Lungs: Humans The alveoli (structures with a large surface area) are the site of gas exchange in the lungs of mammals and birds. Video

10. St. Francis Xavier University Gas Exchanges Gases enter or leave the circulatory system by diffusing down concentration gradients. Video

11. St. Francis Xavier University Ventilation Mammals utilize a negative pressure system to bring air into lungs—they inhale by suction

12. St. Francis Xavier University LRC: Dogs Motion of thoracic complex and ‘visceral piston’ shown by high speed x-ray cinematographic images of a dog galloping on a treadmill. Locomotor respiratory coupling in mammals. Bramble (1989). American Zoologist. 29 (1)

13. St. Francis Xavier University LRC: Humans Humans utilize LRC while running. 2:1 (Footfall:Breath)