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Content Curator
Nervous tissue is the fundamental component of our neurological system. It monitors and regulates the body's processes.
- Nervous tissue is made up of two types of cells: Nerve Cells or Neurons and Glial Cells, which aid in the transmission of nerve impulses and provide nutrition to neurons.
- The brain, spinal cord, and nerves are made up of nervous tissue designed to be stimulated in order to rapidly transport stimuli from one part of the body to another.
- The spinal cord and brain compose the central nervous system (CNS), while the branched peripheral nerves of the peripheral nervous system (PNS) control and regulate the body's functions and activities.
Key terms: Nerves, Cells, Tissue, Neurons, Central nervous system, Peripheral nervous system, Brain, Neural Tissue
What is Nervous Tissue?
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Nervous tissue, also known as neural tissue, is the fundamental tissue component of the nervous system.The nerve tissue is the collection of neurons and fibres which makes the nervous system in the body.
- Nervous tissue mainly consists of two types of cells: nerve cells or neurons, and glial cells.
- Nerve cells live longer, having a length of one meter, they do not divide and cannot be replaced (except memory cells).
Nervous Tissue Diagram
- The nervous tissue is specialized for being stimulated, transmitting the stimulus from one part to another part of the body rapidly. Thus, it monitors and regulates the functions of the body.
- The nervous tissue is present in CNS and PNS. The Central nervous system formed by the spinal cord and the brain and the peripheral nervous system's peripheral nerves that control and regulate the body's functions and activities. The nervous tissue is located in the peripheral nerves all through the body and in the organs of the central nervous system such as the spinal cord and the brain.
Also check: Control and Coordination
Structure of Nervous Tissue
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The nervous tissue comprises two types of cells:
- Nerve cells or neurons
- Glial cells
Nerve cells or neurons
The nerve cell (neuron) is the fundamental communication unit of the nervous system. Neurons secrete chemicals called neurotransmitters which are responsible for stimulating other neurons as a result of a stimulus or response.The nerve cell has the following parts.
Cell Body
A cell body, which includes a nucleus, Golgi body, endoplasmic reticulum, mitochondria, and other parts, is a part of every neuron.
Dendrites
These resemble branches and are involved in the transfer of messages from other neurons to the cell body.
Axon
The axon, which resembles a tube, is responsible for transmitting electrical impulses from the cell body to the axon terminals, which then send the impulse to a neighbouring neuron.
Synapse
A synapse is where nerve impulses between two nerve cells (neurons) or a neuron and a gland or muscle cell are sent (effector). It is sometimes referred to as a neural junction.
Information in a neuron is one-directional. It passes through neurons from dendrites, across the cell body down the axon to the next neuron.
Glial cells (Neuroglia)
Glial cells help to transmit nerve impulses and also provide nutrients and nourishment to the neurons.
- Glia, also called glial cells or neuroglia.
- They are non-neuronal cells in the central nervous system and in the peripheral nervous system.
- They do not produce any electrical impulses. They maintain homeostasis (fixed nature), produce myelin (the liquid that protects and nourishes the neurons) in the peripheral nervous system, and provide support and protection for neurons. Myelin is the protective sheath covering the neurons.
Glia cells are further divided into the following categories.
Central Nervous System
Ependymal cells line the fluid-filled ventricles of the brain as well as the spinal cord's central canal.
- Astrocytes maintain contact with both capillaries and neurons in the CNS. They give nutrients and other materials to neurons, control the levels of ions and chemicals in the extracellular fluid, and support synapses structurally.
- Microglia scavenge and destroy dead cells while guarding against microbial infection of the brain.
- Oligodendrocytes in the CNS create myelin sheaths surrounding axons. One oligodendrocyte may myelinate several axons, and many neurons can get myelin from a single oligodendrocyte.
Peripheral system
In the Peripheral system,
- Satellite glia supply nutrition and structural support to neurons in the PNS.
- Schwann cells function as PNS myelinating cells and peripheral neuron support cells. By enveloping its plasma membrane concentrically around the inner axon, a Schwann cell creates a myelin sheath.
Peripheral System
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Location of Nervous Tissue
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The nerve tissue or nervous tissue is the main component of the two primary parts of the nervous tissue - the central nervous system (CNS) created by the spinal cord and the brain, and the peripheral branched nerves of the peripheral nervous system (PNS) which control and regulate the body's functions and activities.
Nervous tissue can be found throughout the body in both peripheral nerves and central nervous system components such as the spinal cord and brain.
Nervous Tissue Characteristics
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Nervous tissue is one of the four major types of tissue. It is a specialised tissue that is present in both the peripheral and central nervous systems.
- It contains glial cells and neurons, two particular types of cells.
- It comprises dendrites, cell body ends, axons, and nerves.
- In response to stimuli, the neurons release chemical neurotransmitters that excite other neurons.
- Information in a neuron is unidirectional. It passes through neurons from dendrites, across the cell body down the axon to the next neuron.
Types of Nerves
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There are four types of nerves in the nervous tissues on the basis of their functions, they are as follows.
Motor Nerves
Motor neurons or motor nerves send signals or impulses from the spinal cord and brain to all the muscles of the body.
- Thus, motor nerves carry the impulses for motor functions.
- The impulse is the signal which lets humans carry out their basic activities such as talking, walking, drinking water, blinking their eyes, sitting, sleeping, etc.
- Any damage to the motor neurons would result in muscle weakness and shrinking.
- For example, The sciatic nerve passes from the lower back to the hips and enables the complete leg to move which consists of various nerves.
Sensory Nerve
The sensory nerves or sensory neurons are responsible for generating impulses or signals which are different from the impulses carried by the motor neurons.
- The sensory neurons gather sensory information such as pressure, pain, temperature, etc from the sensors in the muscles, skin and other internal organs and then redirect it back to the brain and spinal cord.
- These sensory nerves communicate the information related to motion (except for the eyes, as they themselves do it).
- Damage to the sensory nerves can cause numbness, pain, tingling sensation and even hypersensitivity
Also check: Sensory Perception
Autonomic nerve
The autonomic nerves system controls the actions of the automatic systems of the body, such as the muscles of the heart, such as smooth muscles located in the stomach and in the interlining of glands.
- The autonomic nerves control and regulate the functions that are not under voluntary control, i.e., they are involuntary actions.
- There are two divisions in the autonomic nervous system:
- The sympathetic nervous system, which is responsible for the heart rate and all other actions related to flight or fight responses, such as reduced digestion, extra adrenaline, etc.
- The parasympathetic nervous system which controls activities such as excretion, digestion, and other related metabolic actions
Also check: Difference between Sympathetic and Parasympathetic Nervous System
Functional divisions in the autonomic nervous system
Cranial Nerve
The cranial nerves transmit the impulses from the brain to all the organs which are present in the skull.
- They only occupy and regulate all the functions related to the skull.
- The cranial nerves are essential in smell, vision, movement of the face and eyes, movements of the tongue and salivation.
- They emerge from the lower side of the brain.
- There are 12 pairs of cranial nerves in the body:
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Spinal accessory
- Hypoglossal nerves
Cranial Nerves
Functions of Nervous Tissue Functions
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Some nervous tissue functions include:
Interpreting the Surrounding
The interpretation of information from our surroundings is one of the key jobs of the nervous system. The peripheral nervous system's sensory neurons may pick up on changes in pressure, heat, chemicals, colour, and more. The central nervous system receives this information and processes it.
Responding to surroundings
In response to our surroundings, the peripheral nervous system's motor neurons collaborate with the central nervous system. This enables any motion, including talking, sprinting, and even shifting our eyes to focus on novel stimuli.
Internal Conditions Monitoring
Our interior environment is constantly monitored by nervous tissue in addition to the external surroundings. Sensory neurons send information to the central nervous system after detecting changes in temperature, pH, and other parameters. This enables our body to keep an eye out for any issues with our organ systems.
Monitoring homeostasis
Homeostasis is also regulated by nervous tissue. The central nervous system receives information from sensory neurons that are keeping an eye on our inside surroundings. Here, information may be transmitted back to the body so that it can adjust in order to maintain homeostasis or the stability of the body's systems.
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Things to remember
- The cells of the nervous tissue are specialised and modified to get stimulated (excited) and then transmit the response very rapidly from one place to another within the body.
- The brain, spinal cord and nerves are all composed of nervous tissue.
- Nervous tissue is present as the major tissue in the CNS and PNS of the nervous system
- Nervous tissue also contains cells that do not transmit impulses but rather support the neurons' functions. These are the neuroglia, also known as glial cells.
- Neurons secrete chemical neurotransmitters which are responsible for stimulating other neurons as a result of a stimulus and carrying on the impulses.
- The gap between the nerve endings and the next dendrites is called a synapse.
Sample Questions
Ques. What are the different types of nerves? (1 marks)
Ans. There are four types of nerves in the nervous tissues on the basis of their functions, they are
- Motor Nerve
- Sensory Nerve
- Autonomic nerve
- Cranial Nerve
Ques. Which neurons are classified on the basis of their shape? (3 marks)
Ans. On the basis of their shape neurons are classified as follows
- Unipolar cells have a single process that emerges from the cell. Since only invertebrate species have true unipolar cells, it is more accurate to refer to human unipolar cells as "pseudo-unipolar" cells. Unipolar cells in invertebrates lack dendrites.
- Bipolar cells have two opposing processes that extend from each end of the cell body. One is the dendrite, the other the axon. Bipolar cells are extremely rare. They are mostly located in the retina and the olfactory epithelium.
- Multipolar neurons are any neurons that are not unipolar or bipolar. They have two or more dendrites, often many more, and one axon.
Ques. What is the function of nervous tissue? (3 marks)
Ans. The functions of Nervous Tissue
- Nerve cells called neurons create and carry out specific signals. By secreting chemical neurotransmitters, they generate electrical impulses that may travel long distances.
- Responding to stimulus
- Carries out communication and integration
- Insulates electrical systems and clears away dirt from nerve cells
- Carries signals to the cell body from other neurons.
- Coordinates information from all body areas and transmits nerve impulses that regulate all movement.
Ques. How many systems are present in the nervous system? (5 marks)
Ans. The systems present in the Nervous system are
- The Central nervous system (CNS)
The central nervous system is made up of the brain and spinal cord, which coordinate information from all parts of the body and send nerve impulses that regulate all physical actions.
- The Peripheral nervous system (PNS)
Peripheral nerves, which have branches throughout the body, make up the peripheral nervous system. It is directly in charge of regulating the actions of particular body parts and serves as a channel between the CNS and the rest of the body.
- The Sympathetic nervous system (SNS)
When an organism faces a threat and must decide whether to fight or run from it, the SNS becomes active in order to induce a fight-or-flight response in the organism. it activates to trigger a fight-or-flight response in that organism.
- The Parasympathetic nervous system (PSNS)
When an organism is not currently under threat, the PSNS is engaged during the "rest and digest" phases. The PSNS nerves slow down the heart rate and stimulate processes that can happen while at rest, including digestion, waste elimination, and sexual arousal.
Ques. What is nervous tissue? (3 marks)
Ans. Nervous or nerve tissue is the tissue of the nervous system in the body. It is in charge of coordinating and controlling several bodily functions. It promotes muscular contraction, develops environmental awareness, and is important for emotions, memory, and thinking. Cells in nervous tissue must be able to communicate with one another using electrical nerve impulses in order to perform all of these functions. Nervous tissue comprises two cells: nerve cells or neurons, and glial cells. The brain, Spinal Cord, and nerves are made up of nervous tissue. Thus, they make up the central nervous system and the peripheral nervous system too.
Ques What is nervous tissue composed of? (5 marks)
Ans. The nervous tissue comprises two types of cells:
Nerve cells or neurons: Neurons are the fundamental components of the nervous system. These specialised brain cells serve as the brain's receiving and sending information processing units. Every component of the neuron contributes to the transmission of information throughout the body. The different types of neurons are
- Interneurons
- Sensory neurons
- Motor neurons
Glial cells: Glial cells are neurons' supporting cells. Instead of sending electrochemical signals on their own, they foster a favourable environment that supports and shields neurons. Both the central and peripheral nervous systems include the Glia cells. The different types of Glial cells are
- Astrocytes
- Microglial cells
- Ependymal cells
- Oligodendrocytes
- Satellite cells
- Schwann cells
Ques. Write a short note on nerve cells. (5 marks)
Ans. The fundamental components of the nervous system are neurons. The information-processing parts of the brain that are in charge of receiving and delivering information are these specialised cells. Every component of the neuron contributes to the transmission of information throughout the body.
Neurons are responsible for carrying messages from the brain to various muscle groups in the body and sensory data from external stimuli.
Nerve cells or neurons consist of a Cell body, axon, and nerve endings broadly.
- The primary and initial part of the neuron is the cell body which comprises a nucleus, cytoplasm and cell organelles. The cell body of a neuron has extensions. Extensions of the cell membrane are referred to as processes.
- Dendrites are highly branched processes which are responsible for receiving information from other neurons around them and synapses (specialized points of contact).
- Axon is a long stem-like projection emerging out of the cell which is responsible for communicating with other cells called the Target cells and thereby passing impulses. Each neuron has one axon.
Ques. What are terminal buttons? (3 marks)
Ans. The terminal buttons are found at the neuron's end and are responsible for transmitting the signal to neighbouring neurons.
- The terminal button has a synapse—a gap—at the end.
- Signals are sent from one neuron to another through neurotransmitters.
- Neurotransmitters are then released into the synaptic gap when an electrical signal reaches the terminal buttons.
- It Contains vesicles containing neurotransmitters, transforms electrical signals into chemical signals and is also responsible for reabsorbing any surplus neurotransmitters produced during this phase.
Ques. What are the functions of nerve cells? ( 2 marks)
Ans. Every nerve cell in the human body has the primary function of transmitting the information. But the following processes are also carried out by nerve cells:
- It facilitates the body's reaction to external stimuli.
- It assists the body in the proper conduction of metabolic processes.
- Both voluntary and involuntary movements of the body parts are assisted by it.
- It facilitates message transmission without interruption, establishing a connection between the central nervous system and various bodily areas.
Ques. What happens when a neuron delivers an electrical impulse? (3 marks)
Ans. When a neuron delivers an electrical impulse, the following occurs:
- The signal passes down the axon, which is the nerve's "wire" link.
- At the axon hillock, which is located at the end of the nerve, the message is converted to a chemical signal.
- The substance discharges chemicals known as neurotransmitters into a space that connects one neuron to another. These connections are known as synapses.
- A receptor on the muscle or connected neuron attaches to the neurotransmitter, which then converts it into a different electrical signal.
- Electrical impulses go along the next neuron's length.
- Until the message reaches its target, the procedure is repeated.
Ques. Where is the nervous tissue located? (5 marks)
Ans. The primary location of nervous tissue is in the nervous system, which includes the brain, spinal cord, and nerves. This occurs in both the central and peripheral nervous systems.
The brain and spinal cord are the two primary components of the central nervous system. White matter, grey matter, and nerves make up the brain and spinal cord. The brain acts as a central computer, processing information as its main task. The spinal cord communicates with the brain and the body. Long nerves that enter and leave the spinal column through the vertebrae make up this structure.
The peripheral nervous system also contains nervous tissue. All nerves and neurons outside the brain or spinal cord are considered to be a part of the peripheral nervous system. This area's primary job is to pick up stimuli from the environment and communicate movement instructions to the body.
Ques. Explain the types of Neurons. (5 marks)
Ans. Cells called neurons have the ability to send signals known as action potentials or nerve impulses. A neuron's electrical membrane potential experiences a brief rise and fall known as an action potential, which is used to send signals from one neuron to the next. There are three types of neurons.
- Sensory neurons, also known as afferent neurons, transmit information from the PNS to the CNS; several types of sensory neurons can sense temperature, pressure, and light.
- Motor neurons, also known as efferent neurons, carry signals from the CNS to the PNS, where they supply information to sensory neurons in order to "teach" them what to do (e.g., initiate muscle movement).
- Interneurons serve as connectors to create neural circuits and are involved in reflex actions and higher-order brain activities like decision-making. They connect sensory and motor neurons to the brain and spinal cord.
While neurons can be specialised and appear very different from one another, they all share certain components. Every neuron has a soma, or cell body, which contains the nucleus, axon, and dendrites.
Ques. What are Neuroglia and their function? (3 marks)
Ans. The Neuroglia are a collection of cells that support the neurons. Furthermore, they assist in nutrition and maintain the myelin sheath. They also maintain homeostasis. It resides in both the PNS and CNS.
The function of Neuroglia is as follows
- It provides necessary nutrition. It provides neurons with oxygen.
- It kills pathogens. It helps in neuron protection.
- It offers structural stability. It creates a framework of support for the neurons to live in.
- The myelin sheath is another thing it contributes to. The nervous system's ability to operate depends on the sheath. It stimulates and hastens the conduction of electrical impulses. It does this by encircling the axons.
- Additionally, it supports the neurons' ability to stay in a state of homeostasis. A cell can maintain homeostasis to keep its internal environment steady in the face of disruptions.
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