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What is a Neural Tissue?

 Neural tissue is also called as the nervous tissue. The neural tissue is the main component of the nervous system – both the central nervous system and the peripheral nervous system. 

  • This includes the brain, spinal cord, and other types of nerves. In two words, if we have to describe the functions of the neural tissue, we can specify that integration and communication are the main functions of this specialized tissue.
  • The neural tissue consists of mainly the neurons and the neuroglia. The neurons or the nerve cells are highly specialized cells that have the ability to generate and also conduct nerve impulses.  
  • There are supporting cells in the form of neuroglia that help remove the debris, give physical support along with providing electrical insulation.

The Neuron

The neuron is the basic unit of the neural system. Neuron or Nerve cell is made up of cell body & cell process – (Dendron and Axon = Neurites)

NeuronNeuron

(i) Cell body or Cyton or soma or perikaryon:-

  • It contains uninucleated cytoplasm.
  • Except centriole, all cell organelles are found in cytoplasm.
  • Centriole is absent or immaturely present in the nerve cell thus cell division is absent.
  • Some other cell organelles like Nissl's granule and Neurofibril are also found in nerve cell.

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Nissl's granules:

  • Endoplasmic reticulum coils around the ribosome and form granule like structure called as Nissl's granules or Tigroid body.
  • It is the centre of protein synthesis.
  • Chemically – Ribonucleoprotein containing Iron.
  • Site – Cyton & dendron (Rod shape)
  • Many small fibrils are found in the cytoplasm called neurofibrils, these help in internal conduction in the cyton.

(ii) Cell processes: 

(A) Dendron:– It is small cell process. It's fine branches are called dendrites. Some receptors are found on the dendrites, so dendron receive the stimuli & produce centripetal (towards the cell body) conduction.

(B) Axon (Long process = Axon = Nerve fibre) – It is longest cell process of cyton, its diameter is uniform. It contain axoplasm.

  • Nissl's granules are absent in the axoplasm. (Axoplasm of axon contains only neurofibrils and mitochondria). 
  • Axon is covered by axolemma. Part of cyton where axon arises called axon hillock.
  • The axon hillock is the neuron's trigger zone, because it is the site where action potential are triggered.
  • The terminal end of axon is branched in button shape branches which are called as Telodendria.
  • More mitochondria are found in the telodendria which synthesize Acetylcholine (Ach) with the help of choline acetyl transferase enzyme.
  • ach is stored in the vesicles.
  • Axon is the functional part of nerve cell, therefore term nerve fibre usually refer to Axon.

Differences between Axon & Dendron:

 Axon Dendron
 It is always single. One or more.
 It has Neurofibrils but no Nissl's granules. It has both.
 It is long sized process. Small sized
 Nerve impulse travels away from the cell body. (Centrifugal) Nerve impulse travels towards the cell body.(Centripetal)

Axon is covered by a layer of phospholipids  (sphingomyelin) which is called as medulla or myelin sheath.

  • Medulla is covered by thin cell membrane, which is called as neurilemma or sheath of schwann cells.
  • The neurilemma is composed of schwann cells.
  • Schwann cell takes part in the deposition of myelin sheath (myelinogenesis).

Myelinogenesis in the Peripheral nervous system (PNS):– In the peripheral nerves, myelinogenesis begins with the deposition of myelin sheath in concentric layer around the axon by schwann cells.

  • Myelin sheath is discontinuous around the Axon. These interruptions where Axon is uncovered by myelin sheath are called node of Ranvier.

Types of Neurons | Biology Class 11 - NEET

Central nervous system and Peripheral nervous system


Myelinogenesis in the Central nervous system (CNS) :– Neurilemma or schwann cells are not present therefore myelinogenesis process occurs with the help of oligodendrocytes (Neuroglia).

  • Neurons in which myelin sheath is present, are called medullated or myelinated neurons. In some nerve cells where myelin sheath is absent, called as non medullated or non myelinated neurons.

Collaterals of Axon – These are small process or branches of axon. It's structure is similar to axon. It help in the conduction of nerve impulse in more area.
Gray matter:– It is composed of nerve cells. It consist of cytons & non-medullated nerve fibres (Grey fibers).
White matter – It contain myelinated nerve fibres (White fibres).

Types of Neurons | Biology Class 11 - NEET


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 Types of Neurons

Based on the functionality, the neurons are classified into three types. They are:

  • Sensory neurons or afferent neurons- transmit information from the Peripheral nervous system to the central nervous system.
  • Motor neurons or efferent neurons – transmit information from the central nervous system to the effector organs.
  • Interneurons- here, processes are limited to a local area in the brain or spinal cord.

Based on the structure, neurons are again classified into the following:

  • Bipolar neurons: they have one dendrite and one axon
  • Multipolar neurons:  they have 3 or more processes coming from the cell body. Generally, they have one axon and many dendrites.

    Types of Neurons | Biology Class 11 - NEET

Apolar/Nonpolar Neuron:– No definite dendron/axon. Cell processes 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.

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FAQs on Types of Neurons - Biology Class 11 - NEET

1. What is neural tissue?
Ans. Neural tissue refers to the specialized tissue that makes up the nervous system. It consists of nerve cells called neurons, which are responsible for transmitting electrical signals, and supporting cells called neuroglia, which provide structural and functional support to neurons.
2. What is the function of neural tissue?
Ans. The main function of neural tissue is to transmit, process, and store information. Neurons within the neural tissue are responsible for receiving and sending electrical signals, allowing for communication between different parts of the body and the brain. This enables various physiological and cognitive processes, including sensory perception, motor control, and memory formation.
3. How is neural tissue structured?
Ans. Neural tissue is organized into complex networks of neurons and neuroglia. Neurons consist of a cell body, dendrites, and an axon. The cell body contains the nucleus and other organelles, while dendrites receive signals from other neurons. The axon carries the electrical signals away from the cell body and transmits them to other neurons or effector cells. Neuroglia, on the other hand, provide support, insulation, and nourishment to neurons.
4. What are the types of neurons found in neural tissue?
Ans. There are three main types of neurons found in neural tissue: sensory neurons, motor neurons, and interneurons. Sensory neurons transmit signals from sensory receptors (e.g., in the skin, eyes, ears) to the central nervous system. Motor neurons transmit signals from the central nervous system to muscles or glands, enabling movement and secretion. Interneurons connect sensory and motor neurons, facilitating communication between different parts of the nervous system.
5. How does neural tissue contribute to brain function?
Ans. Neural tissue is fundamental to brain function as it forms the basis of the nervous system. The complex network of neurons in the brain allows for the integration and processing of sensory information, generation of thoughts and emotions, and control of bodily functions. The different regions of the brain, each composed of specialized neural tissue, work together to regulate and coordinate various cognitive and physiological processes that enable human behavior and consciousness.
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