The Nervous System: Structure, Function, and Cellular Communication

The Nervous System: Rapid Communication

Introduction to Nervous System Function

The nervous system enables rapid communication between cells, which is essential for the coordination and function of animal bodies. This system allows organisms to sense, process, and respond to internal and external stimuli efficiently.

• Rapid communication is fundamental for survival, enabling quick responses to environmental changes.

• The nervous system is composed of specialized cells called neurons that transmit information via electrical and chemical signals.

Neuron Structure and Arrangement

Basic Anatomy of a Neuron

All neurons share a similar structural organization, which allows them to efficiently transmit signals throughout the body.

• Cell Body (Soma): Contains the nucleus, mitochondria, and other organelles necessary for the cell's metabolic activities.

• Dendrites: Short, branched extensions that receive incoming information from other neurons or sensory receptors and transmit it toward the cell body.

• Axon (Nerve Fiber): A long, slender projection that conducts nerve impulses away from the cell body toward other neurons, muscles, or glands. The axon may have branched tips called axon terminals or synaptic terminals.

Example: In a typical motor neuron, dendrites receive signals from other neurons, the cell body processes these signals, and the axon transmits the resulting nerve impulse to a muscle or gland, triggering a response such as contraction or secretion.

Diagram Description: Neuron Structure

• The neuron consists of dendrites, a cell body, an axon, and synaptic terminals.

• The trigger zone (axon hillock) is where the action potential is initiated.

• The direction of signal transmission is from dendrites → cell body → axon → synaptic terminals.

Key Terms and Definitions

• Neuron: A specialized cell that transmits nerve impulses.

• Synapse: The junction between two neurons or between a neuron and another cell (e.g., muscle or gland cell), where communication occurs via neurotransmitters.

• Action Potential: A rapid, temporary change in a cell's membrane potential, allowing the transmission of electrical signals along the axon.

Additional info:

• Neurons are classified based on their function: sensory neurons (carry information to the central nervous system), motor neurons (carry commands from the central nervous system to muscles or glands), and interneurons (connect neurons within the central nervous system).

• Glial cells support and protect neurons but do not transmit nerve impulses.