Ernest G. Martin
Physiology: The Science of the Body
Published by Good Press, 2021
EAN 4057664575340
Table of Contents
CHAPTER II THE MAINTAINING OF LIFE
CHAPTER III THE SOURCES OF FOOD
CHAPTER VI THE SUPPORTING FRAMEWORK
CHAPTER VIII SENSATION—INTERNAL AND CONTACT SENSES
CHAPTER IX SENSATION—DISTANCE SENSES
CHAPTER X THE NERVOUS SYSTEM AND SIMPLE NERVOUS ACTIONS
CHAPTER XI THE BRAIN AND COMPLEX NERVOUS ACTIONS
CHAPTER XII SOME SPECIAL NERVOUS ACTIONS; SMOOTH MUSCLE AND GLAND CONTROL
CHAPTER XIV THE CONVEYER SYSTEM OF THE BODY
CHAPTER XV THE SERVICE OF SUPPLY OF FOOD
CHAPTER XVI THE SERVICE OF SUPPLY OF OXYGEN
CHAPTER XVII THE SERVICE OF REMOVAL OF WASTE
CHAPTER XVIII MORE ABOUT THE USE OF FOOD BY THE BODY
CHAPTER XIX KEEPING WARM IN WINTER AND COOL IN SUMMER
CHAPTER XX THE PERPETUATION OF THE RACE
PREFACE
WHEN Alexander Pope wrote “The proper study of mankind is man,” he was thinking rather of man as a social being than as the possessor of an amazingly complex and interesting body. It is nevertheless true that to one who finds enjoyment in the study of intricate mechanisms or to one for whom that amazing sequence of events which we call life has appeal there is no more fascinating study than the study of the living body. That part of the study of the body which concerns itself primarily with activity and only secondarily with form and structure, makes up the science of Physiology. The way the body works is the central theme.
The practical value of Physiology to the general reader lies in the fact that it forms the basis of all sound rules of hygiene. Life is made up of bodily activities which may be carried on correctly or incorrectly. Carried on correctly they mean health, carried on incorrectly, unhealth. The world is flooded with health-preserving or health-restoring systems, urged upon the public, for the most part, by promoters in search of gain. Such of these as have merit are based on definite physiological principles, and anyone who has a common-sense working knowledge of his own body can order his life in accordance with them, at little or no expense. Moreover, a sound appreciation of Physiology drives home the truth that when the body is really out of order its restoration can be safely intrusted only to the properly trained physician: the man or woman who through years of painstaking study has won insight into the intricacies of the human mechanism and whose honest appreciation of the difficulties of his profession, and courageous sincerity in grappling with them, justify to the full the confidence in which he is held by his community.
Ernest G. Martin.
CHAPTER I
THE SIGNS OF LIFE
PHYSIOLOGY is the study of living things, so the first thing to be asked when we begin to think about physiology is how we are to know whether anything is alive or not. It is usually pretty easy to tell whether a dog or cat is alive or dead, although sometimes when a dog is stretched out on the road we have to look closely to tell whether he has already met his end or is merely courting it by sleeping in the public highway. There are in the world hosts of animals with which we are not familiar, and to tell whether these are alive or dead is often a puzzle. More than one picnicker has been thoroughly surprised by seeing what looked like a bit of dead twig begin to walk away, and recognized the walking stick. On the whole we will agree that the sign of life which we find most reliable is motion of some sort on the part of the living animal. If the stretched-out dog makes breathing movements, we pronounce him alive; if not, we decide that he is dead. It is because the walking stick moves off when disturbed that we know it is not a twig. But while motion is the thing we look for in living animals we know perfectly well that it would be foolish to assert that anything that moves is alive. When the wind is blowing the air may be full of dead leaves and butterflies, all moving, but only part, the butterflies, alive. Unless the motion is produced by the animal itself it is not good as a sign of life. So widespread among animals is the making of movements, either on their own account, or when disturbed, that we shall not often find ourselves mistaken if we decide that an object which remains quiet indefinitely is not a living animal. Now how about the other side of the question? Is anything that moves on its own account or when disturbed to be judged alive?
Suppose that the inhabitants of Mars have finally succeeded in perfecting a flying boat that can be hermetically sealed and shot across space from that planet to our earth. Suppose further, that the first exploring party has set forth on a voyage of discovery, and has reached a point high in our sky from which objects on the earth’s surface begin to be distinguishable. Of course the huge landmarks, cities, lakes, and rivers, have been in view for a long while, and now the explorers are on the lookout for signs of living things. They are watching,