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Saladin: Anatomy & I 12. Nervous Tissue I Text I I © The McGraw-Hill

Physiology: The Unity of Companies, 2003

Form and Function, Third

Saladin: Anatomy & I 12. Nervous Tissue I Text I I © The McGraw-Hill

Physiology: The Unity of Companies, 2003

Form and Function, Third

Neuron Saladin
Multiple neurons of the brain "firing" (artist's conception)

CHAPTER OUTLINE

Overview of the Nervous System 444

Nerve Cells (Neurons) 445

  • Universal Properties 445
  • Functional Classes 446
  • Structure of a Neuron 446
  • Axonal Transport 449

Supportive Cells (Neuroglia) 449

  • Types of Neuroglia 450
  • Myelin 451
  • Unmyelinated Nerve Fibers 453
  • Conduction Speed of Nerve Fibers 453
  • Regeneration of Nerve Fibers 453

Electrophysiology of Neurons 455

  • Electrical Potentials and Currents 455
  • The Resting Membrane Potential 455
  • Local Potentials 456
  • Action Potentials 458
  • The Refractory Period 460
  • Signal Conduction in Nerve Fibers 460

Synapses 463

  • The Discovery of Neurotransmitters 463
  • Structure of a Chemical Synapse 463
  • Neurotransmitters and Related Messengers 464
  • Synaptic Transmission 465
  • Cessation of the Signal 467
  • Neuromodulators 468

Neural Integration 468

  • Postsynaptic Potentials 468
  • Summation, Facilitation, and Inhibition 469
  • Neural Coding 470
  • Neuronal Pools and Circuits 472
  • Memory and Synaptic Plasticity 473

Chapter Review 476

INSIGHTS

  1. 1 Clinical Application: Glial Cells and Brain Tumors 451
  2. 2 Clinical Application: Diseases of the Myelin Sheath 453
  3. 3 Clinical Application: Nerve Growth Factor 455
  4. 4 Clinical Application: Alzheimer and Parkinson Diseases 475

Brushing Up

To understand this chapter, it is important that you understand or brush up on the following concepts:

  • Cations and anions (p. 60)
  • Ligand- and voltage-regulated gates (p. 100)
  • Cyclic AMP as a second messenger (p. 102)
  • Simple diffusion (p. 106)
  • Active transport and the sodium-potassium pump (p. 110)
  • Basic structure of nerve cells (p. 175)

Saladin: Anatomy & I 12. Nervous Tissue I Text

Physiology: The Unity of Form and Function, Third Edition

444 Part Three Integration and Control

If the body is to maintain homeostasis and function effectively, its trillions of cells must work together in a coordinated fashion. If each cell behaved without regard to what others were doing, the result would be physiological chaos and death. This is prevented by two communication systems—the nervous system (fig. 12.1), which is specialized for the rapid transmission of signals from cell to cell, and the endocrine system, which is specialized for sending chemical messengers, the hormones, through the blood. The most important aspect of both systems is that they detect changes in an organ, modify its physiology, and modify that of other organs. Thus, these systems functionally coordinate the organs of the body and play a central role in maintaining homeostasis.

The scientific study of the nervous system is called neuroscience. It includes neuroanatomy, the study of structure, and neurophysiology, the study of function. The branch of medicine that deals with the diagnosis and treatment of neurological disorders is neurology.

Chapters 12 through 16 deal with neuroscience and chapter 17 with the endocrine system. This chapter is primarily concerned with how individual nerve cells work. The next four chapters are concerned with the organization and function of the nervous system at the organ level. The basic parts of a nerve cell were introduced in chapter 5 (p. 175).

Parts The Nervous System
Figure 12.1 The Nervous System.

© The McGraw-Hill Companies, 2003

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