I am becoming increasingly disturbed by the lack of under standing of science revealed by politicians, industrialists and the general public. I am also concerned about the widespread mis use of the word "scientific" which is more and more being used in situations where it is quite inappropriate. As a result, in some circumstances gross overestimates are made as to what science can do. In other circumstances the real power of science is foolishly underestimated and the contributions which it can make are squandered. Science is God is an attempt to explain just what is meant by the scientific approach and to define more closoJ. y what the word "scientific" indicates. It is deliberately brief and controversial because I want it to be read. In fact, the material dealt with in each single chapter really deserves a whole book to itself. In the future I hope that I may be able to give to each subject such full treatment. Meanwhile I hope that this book will stimulate discussion about science and will increase understanding of it. DAVID F."

to Human Physiology D. F. Horrobin Published by MTP Press Limited SI. Leonard's House, Lancaster, England Copyright (c) 1973, D. F. Horrobin ISBN-13: 978. . ()-85200-048-9 e-ISBN-13: 978-94-010-2349-8 001: 10. 1007/978-94-010-2349-8 First pUblished 1973 No part of this book may be reproduced in any form without permission from the publishers except for the quotation of brief passages for the purpose of review Reprinted 1975 and 1976 by the Blackburn Times Press, Northgate, Blackburn BBZ lAB Contents Introduction 2 The Maintenance of a Constant Internal Environment 7 21 3 Biochemistry The Nervous System 45 4 The Endocrine System 5 79 The Body Fluids and Blood 6 93 7 Circulation 105 8 The Respiratory System 119 9 The Kidneys and Urinary Tract 129 10 The Alimentary Tract 137 11 The Reproductive System 145 12 Responses of the Whole Body 159 An Introduction to Human Physiology Author's Preface In many fie1dliof study it is difficult to understand the sig nificance of the part before one understands the whole. Yet one cannot understand the whole without a prior understanding of the parts. The dilemma is one of the most difficult problems to be solved by the teacher and in no subject is it more important than in physiology. In physiology more than in most subjects the part serves the whole and the whole serves the parts in an extraordinarily intimately integrated manner."

Physiology is the study of the normal working of the body. It is essential that its principles should be understood by nurses and doctors, for only if you know how the body works normally can you understand what is happening during disease. This first chapter covers the whole of physiology in outline, so that as later you read the chapters devoted to giving details of the various systems, you will be able to see where each system fits into the scheme of things. THE CELL You can learn a great deal about physiology by considering the requirements of a simple, single-celled organism such as the amoeba. These requirements may be summarized as follows: 1. Supplies. All living organisms require a supply of energy if they are to survive. Plants can obtain their energy directly from the sun and by using very simple inorganic materials they can manu facture all the substances they need. But animals must obtain their energy from the complex materials which they take in as food. The energy is released by the process known as oxidation (burning), in which food is broken down and combined with oxygen to release all the energy which is required. Animals therefore obviously need a supply of food and a supply of oxygen. Since the animal body is largely made up of water, they need a supply of water as well. The amoeba finds it easy to obtain all these materials from the water which surrounds it."

Biochemistry is the study of the chemistry of living organisms, of the ways in which food is used to serve all the many needs of the body. Biochemistry is closely connected with nutrition, the study of the types and amounts of various materials required in the diet. Biochemistry is also inextricably int rtwined with endo crinology, the study of hormones, for most of the hormones exert their actions by altering the behaviour of chemical reactions within the body. The central problem in biochemistry is that of the supply of energy. Energy is needed for a multitude of purposes of which muscular activity is the best known. Energy is required for digestion, and for the functioning of the kidney, the liver, the brain and all the other organs in the body. Energy is also essential for the building up of the complex organic molecules of which the body is con structed. Ultimately, most of the energy utilized on earth comes from the sun. Plants are able to tap this energy source directly by the process of photosynthesis. By using pigments, notably the green chlorophyll, plants can trap the energy of sunlight and use it to build up complex substances such as fat, carbohydrate, protein and nucleic acids. The only raw materials required are carbon dioxide, water and simple inorganic substances such as nitrates which can be extracted from the soil."

of these subjects and should be kept constantly at hand so that it can readily be consulted when difficult topics arise. I hope that it may succeed in reducing the fear with which many nurses face the sciences with which the book deals. Section 1 BIOLOGY 2 The cell and its requirements The world of living things is conveniently and conven tionally divided into two great groups, the animals and the plants. Broadly speaking the important feature which distinguishes plants is that they can manufacture most of the substances they require by trapping and using various forms of outside energy, in particular the energy of sunlight. In the process of photosynthesis they utilize the energy of light to build up complex chemical substances from relatively simple ones. In contrast, animals lack the ability to use light or any other form of outside energy. Instead they must obtain the energy they require by breaking down complex substances which ultimately they always obtain from plants. Plant-eating animals such as cows and sheep obtain these substances directly. Carnivores obtain them indirectly after they have passed through the bodies of other animals."

The study of the normal function of the animal and human organisms and of the diseases which disturb that normal func tion is largely the study of control mechanisms. These control mechanisms are essential for the survival of an organism in a more or less hostile environment. In many ways they clearly resemble the control mechanisms devised by electronic engin eers for running machinery of all kinds and there are many remarkable parallels between biology and engineering. However, it should not be forgotten that the biological systems were on the scene first and that the engineering is a parallel and independent development. It is therefore perhaps a pity that in recent years the study of biological control systems has tended to be dominated by mathematicians and engineers who have moved from these more precise disciplines into biology. As a consequence of this dominance, one often gets the impression that the principles of biological control can be understood only after one has undergone a rather high-powered course in elec tronic control theory. It often seems to be assumed that it is electronics which must do all the teaching while biology and medicine must do all the learning. In fact I suspect that biolo gical control mechanisms are considerably more sophisticated than anything yet available in the world of the physical sciences and that in the long run biology will teach more to control engineers than vice versa."

I first became interested in prolactin a little over two years ago. I was then working in Nairobi and I knew nothing about the hormone apart from its role in lactation. Professor Mohammed Hyder of the Department of Zoology in the University of Nairobi was interested in the endocrine mechanisms which enable Tilapia fish to adapt to water with a very high electrolyte content. He invited me to a seminar given by Professor Howard Bern which was largely concerned with the role prolactin plays in fluid and electrolyte balance in sub-mammalian vertebrates. This inspired me to begin a programme of research into the roles prolactin plays in man and other animals. Very few physiologists or clinicians seem aware of the multifarious effects of prolactin in mammals. This book therefore aims to give a comprehensive account of the mammalian physiology of prolactin and to make suggestions about its possible role in diseases ranging from cancer to mental illness. The two subjects which have been previously widely covered, the roles of prolactin in lactation and in rat mammary cancer, are presented relatively briefly though with a full list of references. Other subjects are dealt with more extenSively and I hope that many research workers and clinicians may find the book helpful.