An introduction to physiology

Preface To The Second Edition

Concentration, sequence, and election are fruitful principles in the higher education.

In 1898 the Committee on Medical Education, appointed by the Harvard Faculty of Medicine, reported in favor of the " concentration " system urged in the committee by the author in common with Professor W. T. Councilman. By this method, the first half-year in the Medical School is devoted to anatomy and histology, the second half-year to physiology and biological chemistry, the third half-year to pathology and bacteriology, and the fourth, fifth, and sixth half-years to practical medicine and surgery. Work under the new system began in the collegiate year of 1899-1900. In 1904, largely through the influence of Professor Bowditch, the seventh and eighth half-years were made elective, each student choosing for himself the studies best suited to his needs.

Concentration provides that the student shall not serve two masters, but shall study at one

VI PREFACE TO THE SECOND EDITION

time only one principal subject, such as physiology or pathology, disciplines that do not yield readily to a divided mind. Sequence provides that a foundation shall be laid before the superstructure is attempted. Students now have an acquaintance with anatomy before they begin the study of physiology. Election somewhat tardily intrusts to university men rarely less than twenty-five years ' of age a voice in the decision of their nearest affairs. The application of these principles to medical teaching has undoubtedly resulted in large savings of time and energy.

The economy of force secured by concentration and sequence has been highly valuable, though not indispensable, in the new teaching of physiology introduced by the author in February, 1900. The traditional teaching of physiology consists of lectures illustrated by occasional demonstrations and, in some instances, by experiments performed by the students themselves. The new method is fundamentally opposite. It consists of experiments and observations by the student himself. The didactic instruction, comprising lectures, written tests, recitations, conferences, and the writing and discussing of theses, follows the student's experiments and considers them in relation to the work of other observers.

PKEFACE TO THE SECOND EDITION Vll

In the old method, the stress is upon the didactic teaching. In the new there is no less didactic teaching, but the stress is upon observation. The old method insensibly teaches men to rest upon authority, but the new directs them to nature.

The new method requires :

1. Printed accounts of the fundamental experiments and observations in physiology, taken from the original sources, and arranged in the most instructive sequence. The reference to the original source should be given in each case.

2. Accessory data grouped about the fundamental experiments. The accessory data should also be taken as directly as possible from the original sources, and the reference given in each case.

3. Apparatus of precision designed with the utmost simplicity upon lines that permit its manufacture in large quantities at small cost.

It is obvious that these conditions cannot be met without prolonged labor. Meanwhile, the annual classes in physiology must be taught. The present volume is a collection of fundamental and accessory experiments in several fields printed in an abbreviated form for the temporary use of Harvard Medical students and other interested persons. This collection is being completed

Vlll PREFACE TO THE SECOND EDITION

and improved as rapidly as possible, and the data for the remaining fields are being brought together. In its final form this material will constitute " A Laboratory Text-book of Physiology."

The Harvard Medical School, January, 1906.

Contents

PAKT I

THE GENERAL PROPERTIES OF LIVING TISSUES

I

Page Introduction ..... 3

Nerve-muscle preparation — Preliminary considerations regarding energy, stimulation) and irritability.

II Introduction . 12

Kinetic theory — Osmotic pressure — Plasmolysis. Isotony — Estimation of osmotic pressure in the blood serum — Surface tension — Electrolysis — Electrolytic solution pressure.

The Electrometer, the Kheochord, and the Cell 34 Surface tension altered by electrical energy — Electrommeter — Kheochord — Long rheochord — Square rheochord — Simple key — Short-circuiting key — Polarization — Pole-changer — Polarization current — Dry cell.

Induction Currents 53

Inductorium — Magnetic induction — Magnetic field. Lines of force — To produce electric induction, lines of magnetic force must be cut by circuit — Electromagnetic induction — On the construction of the inductorium — Empirical graduation of inductorium — Platinum electrodes — Flat-jawed clamp — Pound-jawed

X CONTENTS

Page clamp — Double clamp — Make and break induction currents as stimuli — Extra currents at opening and closing of primary current — Tetanizing currents — Induction in nerves — Exclusion of make or break current. Unipolar Induction 71 m

Kymograph — Long paper kymograph — Light muscle lever — Writing lever — Tuning fork.

IV The Electrical Stimulation of Muscle axd Nbkvs

The Galvanic Current 93

Non-polarizable electrodes — Moist chaml D - : ac-

tion of the brain by pithing — Paralysis of voluntary motion by curare — Opening and closing contraction — Changes in intensity of stimulus.

Polar Stimulation of Muscle 101

Ureter — Gaskell Clamp — Intestine — Electro-magnetic signal — Tonic contraction — Physiological anode and cathode — Polar stimulation in heart.

Polar Stimulation of Xerve 113

Law of contraction — Changes in irritability — Changes in conductivity.

Stimulation of Human Nerves 127

Stinmlation of motor points — Polar stimulation of human nerves — Brass electrodes — Eeaction of degeneration.

Galtanotropism 137

Paramecium.

Influence of Duration of Stimulus 138

Tonic contraction — Ehythmic contraction — Continuous galvanic stimulation of nerve may cause periodic dis-

CONTENTS XI

Page charge of nerve impulses — Polarization current — Polar fatigue — Opening and closing tetanus — Polar excitation in injured muscle.

Polar Inhibition by the Galvanic Current . . . 153

Heart — Polar inhibition in veratrinized muscle. Stimulation affected by the Form of the Muscle 156 Effect of the Angle at which the Current Lines

cut the Muscle Fibres 157

The Induced Current 158

V

Chemical Stimulation 163

Effect of distilled water — Strong saline solutions — Drying — " Normal saline " — Importance of calcium — Constant chemical stimulation may cause periodic contraction.

Mechanical Stimulation . . . . „ 166

Idio-muscular contraction.!

VI

Independent irritability of muscle — Irritability and conductivity are separate properties of nerve — Minimal and maximal stimuli; threshold value — Summation of inadequate single stimuli — Relative excitability of flexor and extensor nerve fibres ; Ritter-Rollett phenomenon — Specific irritability of nerve greater than that of muscle — Irritability at different points of same nerve — Excitation wave remains in muscle or nerve fibre in which it starts — Same nerve fibre may conduct impulses both centripetally and centrifugally — Speed of nerve impulse.

Xll CONTENTS

PAET II

Page

Hydrolysis of Starch by Diastase 189

Conversion of starch to sugar by germinating barley — Conversion of starch to sugar by salivary diastase (ptyalin) — Extraction of diastase from germinating barley — Specific action of ferments.

Proteid Digestion by Pepsin 192

Gastric digestion of cooked beef and bread — Artificial gastric juice — Digestion with artificial gastric juice — Extraction of pepsin — Change of proteid to peptone by pepsin.

Splitting of Casein by Rennin 195

Kennim extract — Separation of rennin — Precipitation of casein — Experiments of Arthus and Pages.

Precipitation of Fibrin by Fibrin Ferment . . . 199 Buchanan's experiment — Extraction of fibrin ferment — Extraction of fibrinogen — Precipitation of fibrinogen by fibrin ferment.

Ammoniacal Fermentation of Urea by Urease . . 201 Extraction of urease.

Splitting and Synthesis of Fats 205

Chemistry of fats and soaps — Splitting of fats by the pancreatic juice — Preparation of neutral fat — The emulsion test for fatty acid — Extraction of lipase — Hydrolysis of ethyl butyrate by lipase — Synthesis of neutral fat by lipase.

CONTENTS Xlll

Page

Immunity 218

Ehrlich's ricin experiments — Ricin antitoxine — Theory of immunity.

Haemolytic and Bacteriolytic Ferments .... 227 Bordet's experiments.

Oxidizing Ferments 230

Schonbein's experiment — Further oxidations by animal tissues — Oxidation by nucleo-proteid — Oxidation about the nucleus — Glycolysis in blood — Oxidation not dependent on living cells of blood — Relation of glycolysis to the pancreas and the lymph — Glycolytic ferment of pancreas.

Alcoholic Fermentation 238

The yeast plant — Chemical relations of carbohydrates.

Activating Ferments 243

Enterokinase — Conversion of trypsinogen to trypsin by enterokinase.

Absorption of Proteids 245

Diffusion of proteids through dead membrane — Diffusion through living intestinal wall — Absorption velocity compared with diffusion velocity — Assimilable proteids — Non-assimilable proteids — Alimentary albuminuria — Albumose and peptone not ordinarily present in the blood or urine — Albumose and peptone changed in their passage through the intestinal wall.

Absorption of Fats, Fat Acids, and Soaps . . . 259 Absorption of fat — Absorption of fat acids — Absorption of fat acid as a soap.

Lymph 262

Permeability of vessel wall in inflammation.

II

Specific Gravity 264

Drawing the blood — Determination of specific gravity. Counting the Corpuscles 266

Counting the red corpuscles — Counting the white cor-

XIV CONTENTS

Page Estimation of Haemoglobin 269

Oxygen capacity of the blood ; the colorimetric determination of haemoglobin.

Haemorrhage and Kegeneration ....... 273

Physical Aspects of Coagulation 273

Physical action of salts in the coagulation of colloidal mixtures — Physical changes in coagulation.

Secretion 276

Speed of absorption and secretion.

Ill Respiration

Chemistry of Respiration 277

Estimation of oxygen, carbon dioxide, and water.

Metabolism 278

Effect of muscular exercise on the oxygen, carbon dioxide, and water of the respired air — Individual level of proteid metabolism — Nitrogenous equilibrium — Effect of muscular exercise on proteid metabolism.

PAET III

I Animal Heat

Animal Heat 285

Regional temperature — Effect of hot and cold drinks on the temperature of the mouth — Hourly variation — Reaction of cold and warm blooded animals to changes in the external temperature — Chemical action the source of animal heat.

CONTENTS XV

II

The Electromotive Phenomena of Muscle and Nerve

Page

The Demarcation Current of Muscle 287

Demarcation current of muscle — Stimulation by demarcation current — Interference between demarcation current and stimulating current ; polar refusal.

Demarcation Current of Nerve 295

Nerve may be stimulated by its own demarcation current.

Hypotheses regarding the Causation of the Demarcation Current 297

Action Current of Muscle 302

Rbeoscopic frog — Action current in tetanus; stroboscopic method — Action current of human muscle — Action current of heart.

Action Current of Nerve 315

Negative variation — Positive variation — Positive after current — Contraction secured with a weaker stimulus than negative variation — Current of action in optic nerve — Errors from unipolar stimulation.

Secretion Current 320

Secretion current from mucous membrane — Negative variation of secretion current.

Electrotonic Currents 323

Negative variation of electrotonic currents ; positive variation (polarization increment) of polarizing current — Electrotonic current as stimulus.

Electric Fish 329

XVI CONTENTS

III

Page

Volume of Contracting Muscle 331

The Single Contraction or Twitch 332

Muscle curve — Duration of the several periods — Excitation wave — Contraction wave — Relation of strength of stimulus to form of contraction wave — Influence of load on height of contraction — Influence of temperature on form of contraction — Muscle warmer — Influence of veratrine on form of contraction.

Tetanus 346

Superposition of two contractions — Superposition in tetanus — Relation of shortening in a single contraction to shortening in tetanus.

The Isometric Method 349

Graduation of isometric spring — Heavy muscle lever — Isometric contraction.

Contraction of Human Muscle 353

Simple contraction or twitch — Ergograph — Isometric contraction — Artificial tetanus — Natural tetanus.

Smooth Muscle 356

Spontaneous contractions — Simple contraction — Tetanus.

The Work Done 358

Influence of load on work done — Absolute force of muscle — Total work done ; the work adder — Total work done estimated by muscle curve — Time relations of developing energy.

Elasticity and Extensibility 363

Elasticity and extensibility of a metal spring — Of a rubber band — Of skeletal muscle — Extensibility increased in tetanus.

Fatigue . 366

Skeletal muscle of frog — Human skeletal muscle.

CONTENTS XV11

IV

Page

Simple Reflex Actions 370

The spinal cord a seat of simple reflexes — Influence of afferent impulses on reflex action — Threshold value lower in end organ than in nerve-trunk — Summation of afferent impulses — Segmental arrangement of reflex apparatus — Reflexes in man.

Tendon Reflexes . 375

Knee jerk — Ankle jerk — Gower's experiment.

Effect of Strychnine on Reflex Action .... 377

Complex Co-ordinated Reflexes 377

Removal of cerebral hemispheres — Posture, etc. — Balancing experiment — Retinal reflex — Croak reflex.

Apparent Purpose in Reflex Action 381

Reflex and Reaction Time 382

Reflex time — Reaction time — Reaction time with choice.

Inhibition of Reflexes 384

Through peripheral afferent nerves — Through central afferent paths; the optic lobes.

The Roots of Spinal Nerves 386

Ludwig's demonstration — Localization of movements at different levels of the spinal cord.

Distribution of Sensory Spinal Nerves .... 388

Muscular Tonus 389

Brondgeest's experiment.

V

Sensations of Temperature 390

Hot and cold spots — Outline — Mechanical stimulation — Chemical stimulation — Electrical stimulation — Temperature after-sensation — Balance between loss and gain

XViil CONTENTS

Page of heat — Fatigue — Eelation of stimulated area to sen sation — Perception of difference — Relatively insensitive regions.

Sensations of Pressure 393

Pressure spots — Threshold value — Touch discrimination — Weber's law — After-sensation of pressure — Temperature and pressure — Touch illusion ; Aristotle's experiment.

' VI General Sensations

Tickle 398

Irradiation — After image — Topography — Summation — Fatigue.

Pain .399

Threshold value — Latent period — Summation — Topography — Individual variation — Temperature stimuli.

Motor Sensations 400

Judgment of weight — Sensation of effort — Sensation of motion.

VII Taste

Taste 401

Threshold value — Topography — Relation of taste to area stimulated — Electrical stimulation.

Introduction to Physiological Optics

Reflection from. Plane Mirrors ....... 403

Angles of incidence aud reflection.

Reflection from Concave Mirrors 405

Principal focus — Conjugate foci — Virtual image — Construction of image from concave mirrors.

CONTENTS XIX

Page Reflection from Convex Mirrors 410

Refraction 410

Refraction by Prisms 413

Construction of the path of a ray passing through a prism.

Refraction by Convex Lenses 416

Principal focus — Estimation of principal focal distance — Conjugate foci — Virtual image — Construction of image obtained with convex lens.

Refraction by Concave Lenses . . 422

Refraction by Segments of Cylinders 422

Refraction through Combined Convex and Cylindrical Lenses 424

Aberration 426

Spherical aberration by reflection — Spherical aberration by refraction — Dispersion circles — Myopia — Hypermetropia — Chromatic aberration — Aberration avoided by a diaphragm.

Numbering of Prisms and Lenses 435

Numbering of prisms — Numbering of lenses.

IX Kefraction in the Eye

The eye as a camera obscura.

The Schematic Eye 438

Cardinal Points of the Cornea (System A) . . . 440 Construction drawing of System A — Principal focal distances — Construction of image — Calculation of position to conjugate foci.

Cardinal Points of the Crystalline Lens (System B) 445 Construction drawing of System B — Optical centre — Nodal points — Principal surfaces — The point s — Principal points — Principal focal distances.

Cardinal Points of the Eye (System C) . . . . 451 Principal surfaces — Nodal points — Principal foci.

XX CONTENTS

Page Calculation of the Situation and Size of Dioptric

Images 456

Reduced Eye 458

Relations of the Visual Axis 463

Visual angle — Apparent size — Size of retinal image — Acuteness of vision — Smallest perceptible image — Measurement of visual acuteness.

Accommodation 469

Schemer's experiment — Dispersion circles — Diameter of circles of dispersion — Accommodation line.

Mechanism of Accommodation 473

Narrowing of pupil — Relation of iris to lens — Changes in the lens.

Measurement of Accommodation ....... 479

Far point — Determination of far point — Near point — Determination of near point — Range of accommodation.

Ophthalmoscopy 484

Reflection from retina — Influence of angle between light and visual axis — Influence of size of pupil — Influence of nearness to pupil — Ophthalmoscope.

Direct Method 490

Emmetropia — Ametropia ; qualitative determination — Measurement of myopia — Measurement of hypermetropia — Measurement of astigmatism. Indirect Method 496

X x

Mapping the blind spot — Yellow spot — Field of vision. Color Blindness 501

Method of examination and diagnosis.

CONTENTS XXI

XI Mechanics of Respiration

Page

Mechanics of Respiration 505

Artificial scheme — Inspiration — Expiration — Normal respiration — Forced respiration — Obstructed air passages — Asphyxia — Coughing ; sneezing — Hiccough — Perforation of the pleura.

XII The Mechanics of the Circulation 508

Circulation scheme.

The Conversion of the Intermittent into a Continuous Flow 515

The Relation between Rate of Flow and Width

of Bed 519

The Blood-Pressure 521

Relation of peripheral resistance to blood-pressure — Curve of arterial pressure in the frog — Effect on blood-pressure of increasing the peripheral resistance in the frog — Changes in the stroke of the pump; inhibition of the ventricle — Effect of inhibition of the heart on the blood-pressure in the frog.

The Heart as a Pump 525

Opening and closing of the valves — Period of outflow from the ventricle — Sphygmograph tambour — Visible change in form — Graphic record of ventricular contraction.

The Heart Muscle 5S0

All contractions maximal — Staircase contractions — Isolated apex ; Bernstein's experiment — Rhythmic contractility of heart muscle — Constant stimulus may cause periodic contraction — Inactive heart muscle still irritable — Refractory period; extra-contraction; compensatory pause — Transmission of the contraction wave in the ventricle ; Engelmann's incisions — Transmission xxii CONTENTS of the cardiac excitation from auricle to ventricle; Gaskell's block — Tonus — Influence of "load" on ventricular contraction — Influence of temperature on frequency of contraction — Action of inorganic salts on heart muscle.

The Heart Sounds 541

The Pressure-Pulse 543

Frequency — Hardness — Form — Volume — Pressure-pulse in the artificial scheme — Human pressure-pidse curve — Low tension pressure-pulse — Pressure-pulse in aortic regurgitation — Stenosis of the aortic valve — Incompetence of the mitral valve.

The Volume Pulse 552

XIII The Innervation of the Heart and Blood-Vessels

The Innervation of the Heart and Blood- Vessels 554

The Augmentor Nerves of the Heart 555

Preparation of the sympathetic — Action of sympathetic on heart.

The Inhibitory Nerves of the Heart 558

Preparation of the vagus nerve — Stimulation of cardiac inhibitory fibres in vagus trunk — Effect of vagus stimulation on the auriculo-ventricular contraction interval — Irritability of the inhibited heart — Intracardiac inhibitory mechanism — Inhibition by Stannius ligature — Action of nicotine — Atropine — Muscarine — Antagonistic action of muscarine and atropine.

The Centres of the Heart Nerves 564

Inhibitory centre — Augmentor centre — Reflex inhibition of the heart ; Goltz's experiment — Reflex augmentation.

The Innervation of the Blood-Vessels .... 568

Bulbar centre — Vasomotor functions of the spinal cord — Effect of destruction of the spinal cord on the distribution of the blood — Vasomotor fibres leave the cord in the anterior roots of spinal nerves — Vasoconstrictor fibres in the sciatic nerve — Vasodilator nerves — Reflex vasomotor actions.

ILLUSTRATIONS

Diagrams which merely illustrate the grouping of apparatus for a particular experiment are omitted from this list.

Fig. Page

1. Muscles of left hind limb of frog, dorsal view . . 6

2. Nerve-muscle preparation 7

3. Muscle clamp, stand, and nerve-holder .... 8

4. Tension indicator 25

5. Stage electrometer . 38

6. Long rheochord 43

7. Square rheochord 44

8. Simple key 45

9. Short-circuiting key 46

11. Pole-changer, early form . 49

12. Rocking key 50

14. Inductorium 54

15. Platinum electrodes 65

16. Flat-jawed clamp and round-jawed clamp .... 66

17. Double clamp 6Q

19. Long paper kymograph 82

20. Smoker 84

21. Light muscle lever 86

22. Tuning fork 87

23. Non-polarizable electrodes 94

24. Moist chamber 95

25. Hind limb of frog, anterior view 99

25. Gaskell clamp 103

26. Electro-magnetic signal 105

28. Frog board 112

XXIV ILLUSTRATIONS

Fig. Page

35. Motor points on the anterior surface of the forearm

and hand 128

36. Motor points on the posterior surface of the forearm 129

and hand

38. Brass electrodes 132

42. Gas chamber, with bottle for generating carbon

dioxide 172

43. Sartorius 181

44. Gracilis 183

48. Scheme of myomeres in a parallel- fibred muscle . . 298

49. Scheme of myomeres in an oblique section . . . 299

50. Vibrating interrupter 303

51. Vibrating interrupter arranged to make one contact

per second . 304

53. Heart lever * . 311

54. Scheme of differential rheotome 313

58. Volume tube 332

59. Muscle warmer 343

60. Heavy muscle lever 351

61. Ergograph 354

62. Work adder 359

63. Lantern and optical box 404

65. Reduced eye 459

67. Respiration scheme 504

68. Quantitative circulation scheme 512

69. Mercury manometer 523

70. Sphygmograph 527

71. Sphygmograph tambour ......... 528

72. Scheme of sympathetic nerve in frog 556

73. Scheme of cervical nerves in frog 558

74. View of brain of frog from above 565

Part I The General Properties Of Living Tissues

PART I

THE GENERAL PROPERTIES OF LIVING TISSUES