Anatomy & Physiology I and II

Anatomy & Physiology Study Guide • Activation energy is the amount of energy required to start a reaction. Enzymes are catalysts— compounds that accelerate chemical reactions without themselves being permanently changed or consumed. Enzymes promote chemical reactions by lowering the activation energy requirements. • Inorganic compounds usually lack carbon, and organic compounds always contain carbon: Body fluid pH is vital for homeostasis: • The pH of a solution indicates the concentration of hydrogen ions it contains. Solutions are classified as neutral, acidic, or basic (alkaline) by the pH. Acids, bases, and salts are inorganic compounds with important physiological roles: • An acid releases hydrogen ions; a base removes hydrogen ions from a solution. Strong acids and strong bases ionize completely, whereas weak acids and weak bases do not. • A salt is an electrolyte whose cation is not hydrogen ( H + ) and whose anion is not hydroxide. • Buffers remove or replace hydrogen ions in solution. Buffers and buffer systems in body fluids maintain the pH within normal limits. Carbohydrates contain carbon, hydrogen, and oxygen in a 1:2:1 ratio: • Carbohydrates are most important as an energy source for metabolic processes. The three major types of carbohydrates are monosaccharides (simple sugars), disaccharides, and polysaccharides. Lipids contain a carbon-to-hydrogen ratio of 1:2: • Lipids include fats, oils, and waxes; most are water-insoluble molecules. The five common classes of lipids are fatty acids, eicosanoids, glycerides, steroids, and phospholipids and glycolipids. • Triglycerides (neutral fats) consist of three fatty acid molecules attached by dehydration synthesis to a molecule of glycerol.

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