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What is Nervous
System?
To control and coordinate all kinds of activities in our body, there is a complex network made up of tissues, cells and organs called the "nervous system". It plays a crucial role in our
ability to interact with the world around us and to carry out basic functions
such as movement, perception, thought, and emotion.
Parts
of the Nervous System
The
nervous system is divided into two main parts: the central nervous system (CNS)
and the peripheral nervous system (PNS).
Central nervous system
The control center that controls our body's senses, and processing of information, is the central nervous system. The central nervous system is made up of the brain and spinal cord. The brain is the command center, and the spinal cord serves as a pathway for
signals to travel to and from the brain.
(1) The Brain: The brain is the most complex organ
in the human body, and it is responsible for controlling all the body's
functions. It is made up of three parts cerebrum, cerebellum and brainstem
The cerebrum is the largest part of the brain, divided into two hemispheres. It is responsible for
controlling conscious thought, movement, and sensation. The function of coordination and balance in our body is done by the cerebellum which is located in the back part of the brain. Functions in the body like breathing, heart rate and blood pressure are performed by the brainstem, which is located between the brain and the spinal cord.
The brain controls the CNS in our body. It is divided into
several different regions, each of which is responsible for a different set of
tasks. For example, the frontal lobe of the brain is responsible for
decision-making and problem-solving, while the occipital lobe is responsible
for processing visual information.
(2) The Spinal Cord: The spinal cord is a long, thin,
tubular bundle of nerves that extends from the brainstem to the lower back. It
is responsible for relaying messages between the brain and the rest of the
body. The spinal cord is protected by the vertebrae of the spine, which act as
a shield against injury.
The spinal cord is a long, thin bundle of nerves that runs
from the base of the brain down through the spinal column. It acts as a
communication highway between the brain and the rest of the body, transmitting
information back and forth in real-time.
Together, the brain and spinal cord make up the CNS, which
is responsible for everything from regulating the body's temperature to
controlling movement and sensation. Without the CNS, the body would not be able
to function properly.
and disorders. Some of the most common CNS disorders include Alzheimer's
disease, Parkinson's disease, multiple sclerosis, and epilepsy. These disorders
can have a significant impact on a person's quality of life, and can even be
life-threatening in some cases.
There are many treatments available for CNS
disorders, including medications, therapies, and surgeries. With the right
treatment and support, many people with CNS disorders are able to manage their
symptoms and live full, healthy lives.
The
Peripheral Nervous System
The work of connecting different parts of our body with the central nervous system (CNS) is done by the peripheral nervous system (PNS). It is responsible for
carrying messages from the brain and spinal cord to various organs, tissues,
and muscles, and also for receiving information from the external environment
and transmitting it to the CNS.
The PNS
is essential for our survival and helps us to respond to various external
stimuli. For example, if we touch something hot, our PNS sends a signal to the
CNS, which then sends a signal back to our muscles to remove our hand from the
hot object. Similarly, if we are scared or threatened, our PNS activates the
fight or flight response, which prepares our body to either fight or run away
from the threat.
The
PNS consists of two main components: the somatic nervous system and the
autonomic nervous system. The somatic nervous system is responsible for
controlling voluntary movements, while the autonomic nervous system controls
involuntary functions like heart rate, breathing, and digestion.
(1) The
Somatic Nervous System
The somatic nervous system controls voluntary movements and sensations in our body. It is responsible for carrying sensory information
from the body's sensory receptors to the central nervous system (CNS) and
transmitting motor commands from the CNS to skeletal muscles.
The somatic nervous system controls voluntary
movements, such as walking or reaching for an object. It is responsible for the
conscious movements we make. The function of connecting the muscles and sensory receptors in our body is done by sensory and motor neurons, which are located in the somatic nervous system.
When
a person touches a hot stove, sensory receptors in their skin send a message
through the somatic nerves to the spinal cord and then to the brain, which
interprets the sensation as pain. The brain then sends a message back through
the somatic nerves to the muscles, causing a reflexive withdrawal of the hand
from the stove.
The somatic nervous system also contributes to the voluntary movements of the muscles of the skeletal system of our body. When a person decides to move a muscle, the brain sends a
message through the somatic nerves to the muscle, causing it to contract.
The
somatic nervous system is different from the autonomic nervous system, which
controls involuntary movements such as heart rate and digestion. Both the somatic and autonomic nervous systems work together to control our body movements and maintain homeostasis.
Damage
to the somatic nervous system can lead to sensory deficits, such as numbness or
loss of sensation, or motor deficits, such as weakness or paralysis. Conditions
that affect the somatic nervous system include peripheral neuropathy, spinal
cord injuries, and multiple sclerosis.
(2) The
Autonomic Nervous System
system, which is under our conscious control, the autonomic nervous system
operates automatically, hence the name "autonomic."
The autonomic nervous system is made up of the sympathetic nervous system and the parasympathetic nervous system. The
sympathetic nervous system is responsible for preparing the body for action or
stress, while the parasympathetic nervous system is responsible for maintaining
normal body functions and restoring the body to a state of rest after the
stress has passed.
(a) Sympathetic nervous system
Thesympathetic nervous system prepares the body for "fight or flight"
situations. It triggers the release of adrenaline, which increases heart rate
and blood pressure, dilates the pupils, and increases breathing rate. These
responses prepare the body to respond quickly to a perceived threat.
(b) Parasympathetic nervous system
The parasympathetic nervous system is responsible for thebody's "rest and digest" response, which helps to conserve energy and
promote relaxation. This response slows down heart rate and breathing rate
while increasing digestive activity and blood flow to the digestive system. The
parasympathetic nervous system is also responsible for sexual arousal and
promoting the body's natural healing processes.
The
autonomic nervous system plays a crucial role in maintaining homeostasis, which
is the body's ability to maintain a stable internal environment despite changes
in external conditions. This is achieved through a delicate balance between the
sympathetic and parasympathetic nervous systems. For example, when we are
exercising, the sympathetic nervous system is activated to increase heart rate
and breathing rate, while the parasympathetic nervous system is suppressed.
Once we finish exercising, the parasympathetic nervous system takes over,
slowing down our heart rate and breathing rate to help our body recover.
the autonomic nervous system can sometimes malfunction, leading to a variety of
health problems. For example, an overactive sympathetic nervous system can lead
to conditions such as hypertension (high blood pressure), while an overactive
parasympathetic nervous system can lead to conditions such as gastroparesis
(delayed stomach emptying).
How
the Nervous System Works
The
nervous system works by transmitting electrical and chemical signals between
the brain, spinal cord, and other parts of the body. These signals are carried
by specialized cells called neurons.
Neurons
are the basic building blocks of the nervous system. They are responsible for
transmitting electrical signals called action potentials, which allow for
communication between different parts of the body. There are tiny gaps between cells in our body called synapses. Neurons communicate with each other through these synapses.
When
a neuron is activated, it releases a chemical called a neurotransmitter into
the synapse. The neurotransmitter binds to receptors on the next neuron,
causing it to become activated and continue the signal.
Cells
of the nervous system
The
basic building blocks of the nervous system are the cells, which are commonly
known as neurons or nerve cells. There are three main types of cells that make
up the nervous system: neurons, glial cells, and Schwann cells.
(1) N eurons
Neurons
are the main information-processing cells of the nervous system. They receive,
process, and transmit information throughout the body. Neurons have a unique
structure that allows them to perform these tasks. They have a cell body that
contains the nucleus, which is responsible for controlling the cell's
activities. Neurons also have dendrites, which are small branches that receive
information from other neurons, and axons, which are long branches that
transmit information to other neurons.
(2) Glial cells
Glial
cells, also known as neuroglia, are support cells that provide structural
support and nutrition to neurons. They also help remove waste products from the
nervous system. Glial cells do not transmit information like neurons, but they
play an important role in the proper functioning of the nervous system. Astrocytes, oligodendrocytes, and microglia are types of glial cells.
Astrocytes provide structural support to neurons in our body. Oligodendrocytes produce myelin in the body. And myelin also protects neurons. Microglia are immune cells that
protect the nervous system from infection and injury.
(3) Schwann cells
Schwann
cells are a type of glial cell that is found in the peripheral nervous system.
They produce myelin, which helps to insulate the axons of peripheral neurons
and allows for faster transmission of information.
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