CONTENTS xv 



CHAPTER XXI 



THE CIRCULATION OF THE BLOOD. BLOOD PRESSURE AND BLOOD 

 VELOCITY. THE PULSE 



PAGE 



Circulation seen in frog's web. Resistance to blood-flow. Conversion of 

 intermittent into continuous flow. Arterial pressure. Weber's 

 schema. The pulse. Blood-pressure in man. The rate of the blood- 

 flow. Secondary factors affecting the circulation. Aspiration of 

 the thorax. Proofs of the circulation of the blood 318 



CHAPTER XXII 



THE VASOMOTOR MECHANISM. SLEEP. THE LYMPHATIC SYSTEM 



Distribution of blood in different parts of the body. Nerves of the blood- 

 vessels. The vasoconstrictor nerves. The vasoconstrictor center. 

 Depressor nerve. Blushing. Taking cold. Adrenalin. Vasodi- 

 lator nerves. The vasodilator center. Relation of vasomotor tone 

 to cerebral activity. Sleep. Lymphatics. Thoracic duct. Lymph 

 nodes. Movement of lymph 336 



CHAPTER XXIII 



RESPIRATION. THE MECHANISM OF BREATHING. THE REGULATION 

 OF BREATHING 



Definitions. Respiratory organs. Air-passages and lungs. Trachea 

 and bronchi. Structure of lungs. Pleura. Respiratory move- 

 ments. Anatomy of thorax. Expiration. Forced respiration. 

 Respiratory sounds. Capacity of lungs. Hygiene of respiration. 

 Aspiration of thorax. Influence of respiratory movements upon 

 the blood circulation. Influence of respiratory movements on 

 lymph-flow. Respiratory center. Excitation of respiratory center. 

 Eupnea, Dyspnea, Apnea. Asphyxia. Artificial respiration. 

 Modified respiratory movements 348 



CHAPTER XXIV 



RESPIRATION. THE GASEOUS INTERCHANGES 



Nature of the problems. Changes produced in air by being once breathed. 

 Ventilation. Changes undergone by the blood in the lungs. The 

 blood gases. The laws governing the absorption of gases by a 

 liquid. The absorption of oxygen by the blood. The oxygen inter- 

 changes in the blood. The carbon dioxid of the blood. Hormone 

 action of carbon dioxid. Tissue respiration 370 



