Nerve Cells and Neuroglia

There are said to be 27,000,000,000 nerve cells in the human brain and there are about ten times as many neuroglial cells. On the whole, nerve cells are large and glial cells are small, so that their weights are about equal. The cytology of nerve cells does not provide any really startling information. There is a nucleus and a nucleolus complete with sex chromatin, and in the cytoplasm there is Nissl substance formed of RNA and endoplasmic reticulum, mitochondria carrying respiratory enzymes, and lipochromes. Fairly certainly the RNA is concerned with the synthesis of proteins which move out along the axon, and the rate of protein synthesis is increased during axon regeneration. The rate of oxygen uptake is very high, and weight for weight is said to be higher than that in any other cell. Its measurement presents great difficulties, as oxygen uptake of nervous tissue in vivo gives values 5 to 100 times those obtained in vitro. The metabolic activity of nerve cells is believed to increase about five times during and after nervous activity. At the same time, the amounts of cytochrome oxidase and RNA present increase, and there is an increased ammonia production suggesting proteolysis. Excessive activity is said to cause a decrease in cytoplasmic protein and a decrease in RNA. There is a vast literature on cytological changes in cells in overaction, exhaustion and after deprivation of sleep, but there cannot be said to be a coherent body of observed facts, let alone a satisfactory biochemical interpretation of the facts

Bloody analogical reasoning

In this paper I will study some of William Harvey's applications of analogies in the Prelectiones Anatomiae Universalis and the Exercitatio anatomica de motu cordis et sanguinis in animalibus. I will show that Harvey applied analogies in many different ways and that some contributed to the discovery of the characteristic 'action' of the heart and pulse and even to the discovery of the blood circulation. The discovery process will be approached as a problem solving process as described in Batens' contextual model. The focus on constraints allows to see Harvey both as a modern because of his extensive use of experimental results and as strongly influenced by an Aristotelian 'natural philosophy interpretation' of anatomy and physiology as, for instance, propagated by Fabricius of Aquapendente

Res Medica, Spring 1962, Volume III, Number 2

TABLE OF CONTENTSABDOMINAL CRISES II: I. S. R. Sinclair. F.R.C.S.NERVE CELLS AND NEUROGLIA: Professor D. Whitteridge, F.R.S. RESPIRATORY INADEQUACY:Charles E. Hope RES MEDICATHE TREATMENT OF RENAL DISEASES: J. A. Calvert. B.Sc. THE EDINBURGH INFLUENCE ON EARLY AMERICAN MEDICINE: Professor Sir Walter MercerSIR CHARLES BELL: Robert A. ButlerOFFICE-BEARERS 1961-1962RETROSPECT—225th SESSIONBOOK REVIE