1. What Is Life? A Guide To Biology First Edition What Is Life? A Guide To Biology First Edition Jay Phelan © 2011 W. H. Freeman and Company CHAPTER 21 Circulation and Respiration

2. FIGURE 21-1 Like a set of highways for the body.

6. FIGURE 21-7 The path of blood flow in the human body.

17. FIGURE 21-10 Rhythmic contractions of the heart.

24. FIGURE 21-16 Diseases of the heart and blood vessels.

31. FIGURE 21-18 The “other” circulatory system.

34. FIGURE 21-19 The lymphatic system supports the circulatory system while fighting illness.

38. FIGURE 21-22 Overview of respiratory gas exchange in animals.

46. FIGURE 21-24 Gills.

51. FIGURE 21-33 Hemoglobin: the oxygen transporter.

55. FIGURE 21-34 The force of particles on you.