Book contents
- Frontmatter
- Contents
- List of contributors
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- How to use this book
- Acknowledgements
- List of abbreviations
- Section 1 Clinical anaesthesia
- Section 2 Physiology
- 1 Cellular physiology
- 2 Body fluids
- 3 Haematology and immunology
- 4 Muscle physiology
- 5 Cardiac physiology
- 6 Physiology of the circulation
- 7 Renal physiology
- 8 Respiratory physiology
- 9 Physiology of the nervous system
- 10 Physiology of pain
- 11 Gastrointestinal physiology
- 12 Metabolism and temperature regulation
- 13 Endocrinology
- 14 Physiology of pregnancy
- 15 Fetal and newborn physiology
- Section 3 Pharmacology
- Section 4 Physics, clinical measurement and statistics
- Appendix: Primary FRCA syllabus
- Index
9 - Physiology of the nervous system
from Section 2 - Physiology
- Frontmatter
- Contents
- List of contributors
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- How to use this book
- Acknowledgements
- List of abbreviations
- Section 1 Clinical anaesthesia
- Section 2 Physiology
- 1 Cellular physiology
- 2 Body fluids
- 3 Haematology and immunology
- 4 Muscle physiology
- 5 Cardiac physiology
- 6 Physiology of the circulation
- 7 Renal physiology
- 8 Respiratory physiology
- 9 Physiology of the nervous system
- 10 Physiology of pain
- 11 Gastrointestinal physiology
- 12 Metabolism and temperature regulation
- 13 Endocrinology
- 14 Physiology of pregnancy
- 15 Fetal and newborn physiology
- Section 3 Pharmacology
- Section 4 Physics, clinical measurement and statistics
- Appendix: Primary FRCA syllabus
- Index
Summary
Structure and function of neurones
The main excitable cell in the nervous system is the neurone. Non-excitable cells or glial cells support neurones and perform various other functions (see Figure NE1). Neurones specialise in processing and transmitting information. The human nervous system contains between 1011 and 1012 neurones. Functionally, neurones are classified as sensory, motor and interneurone. Structurally, a typical neurone is made up of three parts: a cell body, an axon and terminal buttons (Figure NE2). The cell body consists of intracellular organelles by which the cell maintains its functional and structural integrity. The axon originates from the cell body and divides into terminal branches; each branch terminates in enlarged endings called terminal buttons. The axon is a long projection surrounded by supporting cells (oligodendrocytes or Schwann cells). When there is a layer of lipid–protein complex deposited within the Schwann cell membrane, the neurone is said to be myelinated, otherwise it is unmyelinated. Myelination allows saltatory conduction with an accompanying increase in speed of propagation of a nerve impulse. Mammalian neurones have varying fibre diameters and speeds of conduction, as summarised in Figure NE3.
The ionic basis of membrane potential
Membrane potential at rest
As in other excitable tissues in the body, the electrical potential of a neurone in the resting state is more negative on the inside of the cell than on the outside.
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- Fundamentals of Anaesthesia , pp. 388 - 411Publisher: Cambridge University PressPrint publication year: 2009