The Characteristics of Nervous Tissue

Introduction

The cell is a structural and functional unit of the organism. They perform the basic functions of our body. These special clusters of cells work together to form a tissue. Plants and animals have different tissues. There are four types of tissues in animals: Connective Tissue, Epithelial Tissue, Muscular tissue, and Nervous Tissue.

Nervous tissue is the major tissue component of the nervous system. The nervous system regulates and controls the functions and activities of the body. It consists of two parts: the central nervous system (CNS), the brain and spinal cord, and the peripheral nervous system (PNS). It is composed of branched peripheral nerves. It consists of neurons, also known as nerve cells that send and receive impulses, and glial cells, that help to propagate nerve impulses and to supply nutrients to the neurons.

The Central and Peripheral Nervous System

The nervous system can be divided into two main areas: the central nervous system and the peripheral nervous system. The central nervous system (CNS) is the brain, spinal cord, and peripheral nervous system (PNS) is everything else. The brain is contained in the cranial cavity of the skull and the spinal cord is contained in the vertebral cavity of the spine. It’s a bit too simple to say that the CNS is inside these two cavities and the peripheral nervous system is outside them, but that’s one way of thinking about it. There are several elements of the peripheral nervous system that reside within the skull or spinal cavity. The peripheral nervous system is so named because it is located in the periphery, beyond the brain and spinal cord. Depending on the various aspects of the nervous system, the central and peripheral boundaries are not always universal.

The nervous tissue found in both CNS and PNS contains two basic types of cells: neurons and glial cells. Glial cells are one of the many cells that make up the framework of neurons and the tissues that support their activity. Neurons are functionally more important than the two in terms of the communication function of the nervous system.

Types of Neurons

There are trillions of neurons in the nervous system, and the shape of the cells varies greatly. Neurons come in three common forms:

• Multipolar neurons have multiple processes that originate from the cell body (hence the name multipolar). They have dendrites on the perikaryon, often with long axons. Motor neurons, like most central nervous systems, are multipolar neurons
• Bipolar cells have two processes that extend from both ends of the cell body facing each other. One is the axon and the other is the dendrite. Bipolar cells are less common. They are mainly found as part of the olfactory epithelium (where the sensory stimuli are perceived) and the retina of the eye
• Unipolar cells have long axons that leave the perikaryon, but the perikaryon is not at either end of this axon. One end of the axon has dendrites and the other end forms synaptic connections with target cells. Unipolar cells are exclusively sensory neurons with dendrites around them that sense stimuli

Structure of Tissue

It is made up of nerve cells or neurons, each made up of axons. Axons are long stem-like protrusions protruding from a cell that is responsible for communicating with other cells called target cells, thereby relaying impulses. 

The main part is the perikaryon, which contains the nucleus, cytoplasm, and organelles. Elongation of the cell membrane is called a process.

 Dendrites are highly divergent processes for receiving information from other neurons and synapses (special points of contact). Information from other neurons is provided by dendrites and connects to the perikaryon.

Information within a neuron is unidirectional because it travels from the dendrites through the neuron, across the perikaryon, and down the axons.

Nervous Tissue Location

Nervous tissue is found not only in peripheral nerves throughout the body but also in organs of the central nervous system such as the spinal cord and brain. Nervous tissue is made up of nerve cells or neurons. Neurons are specialized cells that respond to stimuli by generating signals through axons, which are elongated structures that arise from the cell body.

The Function of Nervous Tissue

• Neurons generate and execute nerve impulses. They create electrical signals that travel distances by secreting chemical neurotransmitters

• Responds to stimuli
• Nervous Tissue Carries out communication and integration
• Provides electrical insulation to nerve cells and removes debris
• They carry messages from the other neurons to the cell body

Characteristics of Nervous Tissue

• Nervous tissue constitutes the CNS and PNS of the nervous system
• They contain two distinct cells – neurons and glial cells
• The nervous tissue consists of the dendrites, cell body, axon, and nerve endings
• Neurons secrete some chemical neurotransmitters that are responsible for stimulating other neurons as a result of the stimulation
• The presence of specialization at axonal terminals called synapsis
• The nerve cells live long, cannot be divided and replaced (except memory cells)

Conclusion

Nervous tissue is a term for a group of organized cells in the nervous system that controls body movements, sends and receives signals to and from different parts of the body, and controls body functions such as digestion. Nervous tissue can be divided into two main categories: neurons and glial cells. Neurons or nerves transmit electrical impulses, but glial cells do not. Neuroglia has many other functions, such as neuron support and protection.