| | | {|Guanase |Thymus, adrenals, |Changes guanin {| | pancreas | to xanthin {|Adenase |Spleen, pancreas, |Changes adenin Act on purins{| | liver | to hypoxanthin {|Oxidases |Lungs, liver, |Changes hypoxanthin {| | muscles, etc. | to xanthin and to {| | | uric acid ==============+===================+==================+=================== ~Classification of Enzymes.~--Sherman classifies the enzymes of the body according to their effects: 1. The hydrolytic enzymes: (a) Proteolytic or protein-splitting enzymes. (b) Lipolytic or fat-splitting enzymes. (c) Amylolytic or starch-splitting enzymes. (d) Sugar-splitting enzymes. 2. The coagulating enzymes, such as thrombin or thrombase (the fibrin ferment) and rennin, which causes the clotting of milk. 3. The oxidizing enzymes or oxidases (which, if the oxidation be accompanied by a splitting off of amino groups, may be called "deaminizing" enzymes). 4. The reducing enzymes or "reductases." 5. Those which produce carbon dioxide without the use of free "deamidizing" oxygen, such as zymase of yeast. 6. Enzymes causing the breaking down of a larger into a smaller molecule of the same composition, as in the production of lactic acid from glucose. DIGESTION (CHEMICAL) ~Salivary Digestion.~--The table shows that enzymic action begins in the mouth. ~Saliva~, the characteristic secretion of this region, contains the enzyme ptyalin which exerts its influence upon the starches and dextrins. The food mass remains in the mouth for so short a time, however, that a very small percentage of the starch is changed to maltose under salivary digestion. The action of ptyalin, however, continues in the fundus of the stomach until stopped by the acid in the gastric juice.