What is Nervous Tissue?
Nervous tissue is specialized tissue found in CNS
(central nervous system) and PNS (peripheral nervous system); brain and spinal
cord and nerve.
Nervous tissue
is responsible for coordinating and controlling body movements and bodily function.
Know here the embryonic
origin of nervous tissue.
Neurons and Neuroglia
Nervous tissue contains two categories of cells-
1. Neuron or Nerve cell
Neuron has three main parts-
A. Cell body
B. Dendrites
C. Axons
2. Neuroglia
Also, check out here types of
epithelial tissue and types of
connective tissue.
1. Neuron or Nerve cells
The smallest functional unit of the nervous system is a neuron.
Neuron or nerve cell is excitable cells, that generate
electrically signal.
It
is the basic structural and functional unit of the nervous system.
Nerve cells consist of -
Cell
body, dendrites, and axon
Function of Nerve Cells
1. Responsible for conducting the nerve
impulses.
2. Generate nerve impulse fast processing and
transmission of cellular signals.
3. Transmit nerve impulses, send and receive
signals from the brain.
4. Neurons transmit nerve impulses to other cells.
5. Process and transmit information throughout
the body.
6. Responsible for communicating information in
both chemical and electrical form.
Parts of Neurons
1. Cell Body
The cell body is also called soma, it is spherical
in shape contains the nucleus and other organelles.
The cell body is also known as the factory of neurons.
2. Dendrites
Dendrites are a projection of Neurons, it is highly
branched.
It received signals from other neurons and the transfer
of information from one neuron to another is achieved through chemical signals
and electric impulses (electrochemical signals).
Dendrites conduct electrical messages to the neuron
cell body for the cell to function and conduct nerve impulses towards the cell
body.
3. Axon
Axon is also called nerve fibre. A neuron
typically has one axon that connects it with other neurons or with muscle or
gland cells.
Axons carry nerve impulses away from the cell
body.
For example, from the spinal cord, down to the toe.
Types of Neurons
According to function, there are three types of neurons-
1. Sensory neuron
2. Motor Neuron
3. Mixed Neuron
1. Sensory Neuron (Carrying Towards)
The sensory neuron is referred afferent
neuron, which carries impulses from peripheral sense
receptors to the CNS.
Sensory neurons detect inputs from the
environment, convert them into signals (electrical impulses), and carry towards information to the brain and
spinal cord where a response can be generated.
Sensory input is activated from the environment.
For example,
When touching a hot surface with fingertips, the sensory
neuron will be firing, acting, and sending off signals to the rest of the
nervous system about the information they have received.
2. Motor Neuron (Carrying Away)
Motor neurons referred to as efferent
neurons) are the nerve cells responsible for carrying signals away from the central nervous system
towards muscles to cause movement.
Motor Neurons transmit impulses from the spinal
cord to skeletal and smooth muscle and directly all of our muscle movement.
Motor neurons of the spinal cord are part of the CNS and connect to muscles glands and organs throughout the body.
3. Mixed Neuron
Mixed
neurons contain both
afferent axons and efferent axons. They connect the spinal motor and sensory neurons and transfer signals
between sensory and motor neurons.
Afferent
axons carry the impulses from the motor neuron to CNS, and efferent
axons carry the impulse for the CNS to the target organs. So, mixed neurons
carry impulses from the motor neurons to the central nervous system as well as
from the CNS to the target organ.
What are Myelinated and Unmyelinated Neurons?
Myelinated Neurons
Myelinated neurons are neurons with myelinated axons that can
conduct impulses at a faster speed. Axon is covered by a layer of Schwann cell
membranes (myelin sheath).
Neuron with myelin sheath acts as the insulator that helps
to propagate the electronic signal faster.
Unmyelinated Neurons
Unmyelinated neuron in which no myelin sheath surrounding the axon.
Neurons without myelin sheath are a lower
speed of conduction of the nerve signals.
2. Neuroglia or Glial Cells
Neuroglia is nonconductive and non-excitable cells. It does not generate or conduct impulses and not transmit
messages and does not give feedback.
It Provides support and nutrition,
nourishment of cells of the nervous system, and protection.
It helps to protect, nourish and maintain cells
of the nervous system.
Types of Neuroglia
Types of
neuroglia are-
1. Astrocytes
Astrocytes'
function is control of the blood-brain barrier (BBB) and blood flow.
2. Microglial cell
Microglial
cells' function is to remove damaged neurons and infections.
3. Ependymal cell
Ependymal cells
play an important role in cerebrospinal fluid (CSF) homeostasis, brain
metabolism, and the clearance of waste from the brain.
4. Oligodendrocytes
Oligodendrocytes
produce the myelin sheath, which provides support and insulation to axons.
Function of Nervous Tissue
The function of nervous tissue is-
1. Coordination nerve, spinal cord, and brain
2. Muscle movement
3. Mental activity; Integration and communication
4. Control and integrate all body activity
5. Homeostasis
6. Motor function
7. Respond
8. Sensory receptors
9. Support and protect impulse, generating neuron
10. Generate and transmit nerve impulse
11. Regulates and control body function
Get details on types of
muscle tissue and their functions.
0 Comments