Structure & Functions of Neurons

Introduction

Neurons are the fundamental building blocks of the nervous system, responsible for transmitting electrical and chemical signals throughout the body. Understanding the structure and functions of neurons is crucial for comprehending how our nervous system operates. In this section, we will explore the key components of neurons, including dendrites, the cell body, and axons, as well as the role of the myelin sheath and glial cells in neuron function.

Structure and Functions of Neurons

1. Dendrites

• Definition: Dendrites are branch-like structures that extend from the cell body of a neuron.
• Function: Dendrites receive incoming signals or impulses from other neurons or sensory receptors. They act as the input or receiving part of the neuron.
• Example: When you touch a hot object, the sensory neurons in your skin transmit signals through their dendrites to relay the message of heat to your brain.

2. Cell Body (Soma)

• Definition: The cell body, or soma, is the central part of the neuron.
• Function: The cell body contains the nucleus and various organelles necessary for the neuron's metabolic functions. It integrates incoming signals from dendrites and decides whether to generate an output signal.
• Example: The cell body processes information received from dendrites and determines if a muscle contraction is required in response to a stimulus.

3. Axons

• Definition: Axons are long, slender projections that extend from the cell body of a neuron.
• Function: Axons transmit nerve impulses away from the cell body and towards other neurons, muscles, or glands. They act as the output or transmitting part of the neuron.
• Example: When your brain sends a command to your muscles to contract, it does so through the axons of motor neurons.

---

Structure & Functions of Neurons

Structure and Function of Myelin Sheath

The myelin sheath is a protective covering that surrounds axons in some neurons. It is composed of lipids and proteins.

1. Function

The myelin sheath serves multiple functions, including

2. Insulation

It insulates the axon, preventing electrical signals from dissipating or interfering with neighbouring axons. This insulation increases the speed of impulse conduction.

3. Speed Enhancement

Myelinated axons conduct nerve impulses faster than unmyelinated axons. This is essential for rapid and coordinated responses to stimuli.

4. Development

Myelination of axons continues from birth to adolescence. As myelination progresses, responses to stimuli become more rapid and coordinated. In infants, responses are less efficient due to the absence of a fully developed myelin sheath.

Role of Glial Cells

Glial cells, or neuroglia, are non-neuronal cells that support and nourish neurons within the nervous system.

1. Function

Glial cells have various functions, including:

2. Myelin Production

Some glial cells, known as oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system, produce the myelin sheath. They wrap around axons to create this protective covering.

3. Nutrient Supply

Glial cells supply neurons with essential nutrients, such as glucose and ions, required for their metabolic activities.

---

Structure & Functions of Neurons

4. Protection

They protect neurons from harmful substances and provide physical support.

Summary

Neurons are the fundamental units of the nervous system, consisting of dendrites, the cell body, and axons. Dendrites receive incoming signals, the cell body processes and integrates information, while axons transmit signals to other neurons, muscles, or glands. The myelin sheath, composed of lipids and proteins, insulates axons, increasing the speed of impulse conduction. Glial cells, such as oligodendrocytes and Schwann cells, play a crucial role in producing the myelin sheath and supporting the overall function of neurons. Understanding the structure and functions of neurons is essential for comprehending the complexity of the nervous system and how it enables us to perceive and respond to our environment.