Intro | Cytoplasm | Endoplasmic Reticulum | Golgi Complex | Microtubules | Mitochondria | Nucleus | Plasma Membrane | Ribosomes
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Part 3: Multiple-Choice Self-Test
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The internal features of a typical neuron are similar to those of all eucaryotic cells (or all cells other than bacteria). Eucaryotic cells contain a nucleus and other structures called organelles, each of which is bound by membrane. The organelles or substructures within a neuron maintain all basic life processes and, in addition, support the specialized functions of receiving, conducting, and transmitting electrochemical signals.
Tutorial 1 illustrates the main internal structures of a neuron and describes the primary functions of each.
Neurons vary in size, but most fall somewhere between 10 and 20 micrometers in diameter (Arms & Camp, 1995). The human eye is incapable of seeing anything less than 100 micrometers, therefore, the study of this level of anatomy was impossible before the development of the first compound light microscope in the late 16th century. The study of organelles within the neuron ensued only with the development of transmission and scanning electron microscopy; technologies which became available for general research purposes in the 1970's and 1980's, respectively. Scanning electron microscopy allows for visualization of structures approximately 100 micrometers to 8 nanometers in diameter. The resolution of transmission electron microscopy ranges from approximately 50 micrometers to .2 nanometers. Typical sizes of cellular structures include: mitochondria (7 micrometers), ribosomes (20-25 nanometers), microtubules (25 nanometers), and DNA (2 nanometers).
Although each organelle has an important job to play in the life of the cell, not all cells will contain each type. In addition, organelles will vary in number depending on the activity of the cell.
Arms, K. & Camp, P. (1995), Biology (4th ed.). New York: Harcourt Brace College Publishers.
|Suggestions for further study|
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(Society for Ultrastructural Pathology)
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