1. BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 22 Respiration: The Exchange of Gases Modules 22.1 – 22.4

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The air at the height of the world’s highest peak, Mt. Everest, is very low in oxygen –Even expert mountain climbers do not always survive the journey –Thin air can weaken muscles, damage the digestive system, cloud the mind, and sometimes fill the lungs with blood Surviving in Thin Air

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Geese have adaptations that allow them to fly over the Himalayas –Their efficient lungs draw more oxygen from the atmosphere –Their hemoglobin has a high affinity for oxygen –They have a large number of capillaries to deliver this oxygen- rich blood to tissues and muscles

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Gas exchange is the interchange of O 2 and CO 2 between an organism and its environment –It is also called respiration MECHANISMS OF GAS EXCHANGE

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Gas exchange is essential because energy metabolism requires O 2 and produces CO 2 There are three phases of gas exchange 22.1 Overview: Gas exchange involves breathing, the transport of gases, and the servicing of tissue cells

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 22.1 1 Breathing 2 Transport of gases by the circulatory system 3 Servicing of cells within the body tissues Lung O2O2 CO 2 Circulatory system Capillary Cell CO 2 O2O2 Mitochondria

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings O 2 enters an animal and CO 2 leaves by diffusion through a respiratory surface –Respiratory surfaces are made up of living cells 22.2 Animals exchange O 2 and CO 2 through moist body surfaces

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Some animals use their entire skin as a gas- exchange organ –Example: earthworms Figure 22.2A Cut Cross section of respiratory surface (the skin covering the body) Capillaries CO 2 O2O2

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In most animals, specialized body parts carry out gas exchange –Gills in fish Figure 22.2B Capillaries CO 2 O2O2 Respiratory surface (gill) Body surface

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Tracheae in insects –Lungs in land vertebrates Figure 22.2C, D Body cells (no capillaries) CO 2 O2O2 Respiratory surface (tracheae) Body surface Capillary CO 2 O2O2 Respiratory surface (within lung) Body surface

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Gills are extensions of the body that absorb O 2 dissolved in water In fish, gill filaments bear numerous platelike lamellae –Lamellae are packed with blood vessels –They are the respiratory surfaces 22.3 Gills are adapted for gas exchange in aquatic environments

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The structure of fish gills Figure 22.3 Gill arch Direction of water flow Blood vessels Gill filaments Oxygen-poor blood Oxygen-rich blood Lamella Water flow

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Blood flows through the lamellae in a direction opposite to water flow –This countercurrent maintains a diffusion gradient that maximizes the uptake of O 2 22.4 Countercurrent flow in the gills enhances O 2 transfer Figure 22.4 Blood flow through lamellae Water flow over lamellae