Nervous tissue: Structure, Types and Function

In this article we will discuss about the Nervous tissue: – Definition, Structure, Types of Neuron, Classification of nervous tissue and Functions

Nervous tissue

• Nervous tissue are highly specialised to transmitting the stimulus very rapidly from one place to another within the body
• Nerve tissue is the main tissue of our nervous system

Structure of Nervous Tissue

• Nervous tissue consists of two cells: nerve cells or neurons and Neuroglia (glial cell)

Neuron

• They vary in shape and size, all neurons contains three parts- cell body, dendrites and axon
• Cell body which contains the nucleus, cytoplasm and cell organelles
• Dendrite is a highly branched cytoplasmic extension, responsible for receiving impulses
• from outside & pass to the cyton
• Axons are long stem-like projections emerging out of the cell, It conduct nerve impulse away from cell body

Neuroglia

• Glial cells are non conducting cells that protect and nurture as well as support cells of nervous tissue.

Types of Neurons

Unipolar

• Single process arises from cyton (1 Axon)
• E.g. Nervous system of embryo

Bipolar

• Two process arise from cyton (1 Axon and 1 dendron)
• E.g. Retina (Rod and cones) olfactory epithelium

Multipolar

• Neuron which one axon but many dendrons
• E.g. Most of neurons of vertebrates

Nonpolar Neuron

• No definite dendron/axon
• Cell process are either absent or if present are not differentiated in axon and dendrons
• Nerve impulse radiates in all directions
• E.g. Hydra, Amacrine cell of Retina

Pseudounipolar

• In this type, nerve cell has only axon but a small process develop from axon which act as dendron
• E.g. Dorsal root ganglia of spinal cord

Classification of Nervous System

• The nervous system is classified into the central, peripheral and autonomic nervous systems

Central Nervous System

• Central Nervous System is often called the central processing unit of the body
• It consists of the brain and the spinal cord

Brain

• The brain is one of the important, largest and central organ of the human nervous system.
• Brain control unit of the nervous system, which helps us in discovering new things, remembering and understanding, making decisions, and a lot more
• It is enclosed within the skull
• The human brain is composed of three major parts:
  • Forebrain: The anterior part of the brain, consists of Cerebrum, Hypothalamus and Thalamus.
  • Midbrain: The smaller and central part of the brainstem, consists of Tectum and Tegmentum.
  • Hindbrain: The central region of the brain, composed of Cerebellum, Medulla and Pons.

Spinal Cord

• The spinal cord is a cylindrical bundle of nerve fibers and associated tissues enclosed within the spine and connect all parts of the body to the brain
• It begins in continuation with the medulla and extends downwards
• It is enclosed in a bony cage called vertebral column and surrounded by membranes called meninges
• The spinal cord is concerned with spinal reflex actions and the conduction of nerve impulses to and from the brain

Peripheral Nervous System

• Peripheral Nervous System is the lateral part of the nervous system that develops from the central nervous system
• PNS includes two types of nerve fibers
  1. Afferent nerve fibers – These are responsible for transmitting messages from tissues and organs to the CNS.
  2. Efferent nerve-fibers – These are responsible for conveying messages from CNS to the corresponding peripheral organ

Autonomic neural system

• The autonomic neural system is involved in involuntary actions like regulation of physiological functions (digestion, respiration, salivation, etc.).
• It is a self-regulating system which conveys the impulses from the CNS to the smooth muscles and involuntary organs (heart, bladder and pupil)
• The autonomic neural system can be further divided into:
  1. Sympathetic nervous system
  2. Parasympathetic nervous system

Functions of the Nervous System

• The master controlling and communicating system of the body
• Sensory input: detects external and internal stimuli
• Integration: processes and responds to sensory input
• Control of Muscles and Glands
• Homeostasis is maintained by regulating other systems
• Center for Mental Activities

Frequently Asked Questions: –

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