16. Respiratory Stimulants

Respiratory Stimulants. These exalt the functions of the respiratory centre in the medulla, affording deeper and quicker breathing: strychnine, atropine, digitalis, apomorphine, duboisine, emetine, opium (small doses).

17. Respiratory Sedatives (Depressants)

Respiratory Sedatives (Depressants). These lower the respiratory centre's activity, affording shallow and slow respirations: opium, physostigma, gelsemium, aconite, veratrum viride, comum, muscarine, hydrocyanic acid.

18. Pulmonary Sedatives (Gr.

V Agents Acting On The Respiratory System Respirat 48

lung; L. pulmonarius, pertaining to or affecting the lungs). - These lessen the irritability of the respiratory nerves or centre, thereby diminishing cough and dyspnoea. Some directly depress the centre, others remove irritating substances from the passages, others lessen local congestion, others lower the excitability of the vagus end-organs and afferent filaments of the lungs and respiratory tract: opium, morphine, codeine, hydrocyanic acid, belladonna.

19. Sternutatories. Errhines (L. sternutare, to sneeze; Gr.

V Agents Acting On The Respiratory System Respirat 49

in, +

V Agents Acting On The Respiratory System Respirat 50

the nose). - The former cause sneezing; the latter increase nasal secretion when applied to mucous membrane in powdered form: ipecac, quillaja, ammonia, cubeb, etc.

20. Ciliary Excitants (L. cilium, an eyelid, hair-like process). - These, when dissolved in the mouth, promote bronchial mucous expectoration through reflex excitation of the bronchial and tracheal cilia: acacia, ammonium and sodium chlorides, potassium chlorate.

21. Expectorants (L. ex, out of, + pectus, pectoris, the breast). These change the broncho-pulmonary mucous membrane secretion, promoting its expulsion: (a) Nauseating (Sedative) - which, in large doses, cause vomiting, thereby acting mechanically in expelling the mucus, and, in small doses, increase osmosis from the inflamed mucous membrane; they may increase secretion and lower blood-pressure: tartar emetic, ipecac, apomorphine, lobelia, pilocarpus; (6) Stimulating

- which stimulate the bronchial mucous membrane that eliminates them, altering the secretion and facilitating expectoration: senega, squill, ammonium carbonate and chloride, benzoin, balsams of Peru and Tolu, tar, turpentine, garlic, onion, licorice, saccharine substances, ammoniac.