Organism and environment; Energy metabolism; Thermal relationship; Exchanges of salts and water: mechanisms; Exchanges of salts and water: integration; Nitrogen excretion and other aspects of nitrogen metabolism; Renal organs and excretion; Exchanges of oxygen and carbon dioxide: basic principles, respiratory anvironments, and external respiration; Exchanges of exygen and carbon dioxide: transport in body fluids; Circulation; Metabolic responses to oxygen deficiency and lowered availability of oxygen; The active animal.