Life on Earth

Chapter 22
Circulation and Respiration
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The Human Circulatory System
  • The vertebrate heart consists of muscular chambers whose contraction is controlled by electrical impulses.
  • Blood transports dissolved nutrients, wastes, and hormones throughout the body.
  • The blood vessels carry blood to all parts of the body.

    The Lymphatic System
  • Lymphatic vessels resemble the veins and capillaries of the circulatory system.
  • The lymphatic system returns fluids to the blood.
  • The lymphatic system transports fats from the intestine to the blood.
  • The lymphatic system helps defend the body against disease.

    Respiratory Systems Facilitate Gas Exchange by Diffusion

    The Human Respiratory System
  • The conducting portion of the respiratory system carries air to the lungs.
  • Gas exchange occurs in the alveoli.
  • Oxygen and carbon dioxide are transported using different mechanisms.
  • Air is inhaled actively and exhaled passively.
  • Breathing rate is controlled by the respiratory center of the brain.



  • PH Sower © 1997 by Prentice-Hall, Inc.
    Simon & Schuster/A Viacom Company
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