The Structure of the Nervous System
The building blocks of the nervous system are the nerve cells, also called neurons. It is estimated that the human brain possesses 25 billion cells. Like all animal cells, each neuron is bounded by a cell membrane that encloses the contents of the cell—that is, the cytoplasm (cell fluid) and the nucleus. The size and shape of these neurons vary widely, but the structural plan always includes certain elements (Fig. 1–1): a cell body, or soma, and the processes from this cell body, namely an axon (neurite), and usually several dendrites. The neuron diagrammed in Fig. 1–1 has one axon and four dendrites.
KeywordsSpinal Cord Glial Cell Nerve Fiber Dorsal Root Ganglion Schwann Cell
Unable to display preview. Download preview PDF.
- Bradbury MW (1979) The concept of a blood-brain barrier. Wiley, Chichester, pp 1–465Google Scholar
- Davson H (1976) The blood-brain barrier. J Physiol (Lond) 255: 1–28Google Scholar
- Fawcett DW (1966) An atlas of fine structure: the cell, its organelles and inclusions. WB Saunders, Philadelphia LondonGoogle Scholar
- Handbook of Physiology (1977) Section 1: The nervous system, vol I: Cellular biology of neurons. William & Wilkins, Baltimore, pp 1–1238 (in two books)Google Scholar
- Maran TH (1980) The cerebrospinal fluid. In: Mountcastle V (ed) Medical physiology, vol II. 14th ed. Mosby, St. Louis, p 1218Google Scholar
- Peters A, Palay SL, Webster H def (1976) The fine structure of the nervous system. WB Saunders, Philadelphia London TorontoGoogle Scholar
- Waxman SG (ed) (1978) Physiology and pathobiology of axons. Raven, New YorkGoogle Scholar