1. Relate Cause and Effect Why do some animals actively pump water over their gills
Interpret Visuals Contrast the structures of amphibian, reptilian, and mammalian lungs
Explain Describe the events that occur when a mammal respires including the path of air through the lungs.

2. Ch 27 Animal Systems I
27.2 Respiration

3. Gas Diffusion and Membranes
Gases diffuse most efficiently across a thin, moist membrane that is permeable to those gases
Larger the surface area membrane, the more diffusion that can occur.

4. Requirements for Respiration
Large surface area of moist, selectively permeable membrane
Difference in relative concentrations of oxygen and carbon dioxide on either side of the respiratory membrane.

5. Respiratory Surfaces of Aquatic Animals
Some aquatic invertebrates and a few chordates rely on diffusion of oxygen and carbon dioxide through their outer body covering.

6. Respiratory Surfaces of Aquatic Animals
Many aquatic invertebrates and most aquatic chordates exchange gases through gills
Gills
Feathery structures that expose a large surface area of thin, selectively permeable membrane to water
Capillaries
Network of tiny, thin-walled blood vessels.

7. Respiratory Surfaces of Aquatic Animals
May actively pump water over their gills as blood flows through inside
Gas exchange occurs as water passes over the gills.

8. Respiratory Surfaces of Aquatic Animals
Lungs
Organs that exchange oxygen and carbon dioxide between blood and air
Aquatic reptiles and aquatic mammals, must hold their breath underwater.

9. Respiratory Surfaces in Land Invertebrates
Wide variety of respiratory structures
Respire across their skin
Mantle cavity
Book lungs
Tracheal tubes.

10. Book Lungs
Which are made of parallel, sheetlike layers of thin tissues containing blood vessels.

11. Tracheal Tubes
Air enters and leaves the system through openings in the body surface called spiracles
Most invertebrates.

12. Lung Structure in Vertebrates
Lung structure in terrestrial vertebrates varies
Processes of inhaling and exhaling are similar

13. Inhaling brings oxygen-rich air through the trachea (airway) into the lungs
Oxygen diffuses into the blood through lung capillaries
Carbon dioxide diffuses out of capillaries into the lungs
Oxygen-poor air is then exhaled.

14. Amphibian, Reptilian, and Mammalian Lungs
Typical amphibian lung is little more than a sac with ridges.

15. Amphibian, Reptilian, and Mammalian Lungs
Reptilian lungs are divided into chambers
Increase the surface area for gas exchange.

16. Amphibian, Reptilian, and Mammalian Lungs
Mammalian lungs branch extensively
Filled with Alveoli.

17. Alveoli Provide enormous surface area for gas exchange
Enable mammals to take in the large amounts of oxygen required by their high metabolic rates.

18. Bird Lungs
Air flows mostly in only one direction, so no stale air gets trapped in the system
Gas exchange surfaces are continuously in contact with fresh air
Highly efficient
Enables flight, at high altitude for extended time.