Human Nervous System

The nervous system of the human body is the system that transmits stimuli from sensory receptors to the brain and spinal cord, as well as impulses from the brain and spinal cord to other body components. The human nervous system, like the nervous systems of other higher vertebrates, is divided into two main parts: the central nervous system (which includes the brain and spinal cord) and the peripheral nervous system (which includes the rest of the body) (the nerves that carry impulses to and from the central nervous system). The human brain is particularly huge and well developed in comparison to other animals.

Almost everything you do, think, say, or feel is influenced by your nerve system. It is in charge of complex processes like as movement, cognition, and memory, among others. It also plays an important role in the functions of your body that occur without your conscious awareness, such as breathing, blushing, and blinking.

Your nervous system has an impact on every area of your health, including your ability to do the following:

1. Thoughts, memory, learning, and feelings are all part of the human experience.
2. Movements require balance and coordination.
3. Perception and perception of your senses, including how your brain interprets what you see and hear as well as what you taste, feel, and touch
4. Sleep, healing, and the process of ageing.
5. The rhythm of your heartbeat and breathing patterns.
6. Response to stressful situations.
7. Digestion, as well as how hungry and thirsty you feel are all important factors.
8. Body processes, such as puberty.

This intricate system serves as the control centre for your entire body. It helps to control your body’s processes and allows you to be more aware of your surroundings.

Throughout your body, a large network of nerves transmits and receives electrical impulses from and to other cells, glands, and muscles. These nerves are responsible for receiving information from the environment around you. Once the information has been received, your nerves will analyse it and govern your response. It’s almost as though your body contains a massive information highway that runs throughout it.

Neurons

Neurons, also known as nerve cells, are responsible for carrying out the operations of the nervous system by transmitting nerve impulses. They have a high level of specialisation. In other words, if a neuron is destroyed, it will not be able to be replaced because neurons do not go through the process of mitosis. 

Each neuron is composed of three basic components: a cell body (soma), one or more dendrites, and a single axon (outermost fibre).

The Cellular Structure

The cell body resembles the bodies of other types of cells. This organelle contains many of the conventional cytoplasmic organelles, as well as a nucleus with at least one nucleolus. Centrioles, on the other hand, are absent. Because centrioles play a role in cell division, the absence of these organelles in neurons is consistent with the amitotic character of the cell, as previously stated.

Dendrites

Fibers are a term that is sometimes used to describe them. In most cases, but not always, dendrites are short and branching, which increases the surface area available to receive signals from neighbouring neurons. The number of dendrites on a neuron varies depending on its size. Afferent processes are so named because they are responsible for transmitting impulses to the neuron cell body. Each cell body contains only one axon, which is responsible for sending signals to the outside world. In most cases, it is elongated, and it is referred to as an efferent process because it transports impulses away from the cell body.

Axon

Axon collaterals are branches that form on an axon only on rare occasions.

Axons and axon collaterals branch out into several short branches, known as telodendria.

The synaptic bulbs are formed at the distal extremities of the telodendria, which are slightly expanded. Myelin, often known as the myelin sheath, is a segmented, white, fatty material that surrounds many axons in the brain. Cell bodies and unmyelinated fibres make up the grey matter in the central nervous system, whereas myelinated fibres make up the white matter. The nodes of Ranvier are the unmyelinated portions between the myelin segments that are located between the myelin segments. When it comes to function, neurons are classed as afferent, efferent, or interneurons (association neurons) based on the direction in which they transmit impulses in relation to the central nervous system. Afferent neurons transfer impulses in the direction in which they receive them. Afferent neurons, also known as sensory neurons, are responsible for transmitting impulses from peripheral sense receptors to the central nervous system. They often have long dendrites and small axons, which makes them easy to distinguish from one another. Efferent neurons, also known as motor neurons, are neurons that carry impulses from the central nervous system to effector organs such as muscles and glands. Efferent neurons have short dendrites and long axons, which distinguish them from afferent neurons. Interneurons, also known as association neurons, are neurons that are found entirely within the central nervous system (CNS), where they serve as a connecting link between afferent and efferent neurons. They have short dendrites and either a short or a long axon, depending on the species.

Neuroglia

Neuroglia cells do not transmit nerve impulses; rather, they provide support, nourishment, and protection to the neurons they surround. They outnumber neurons in both number and ability to undergo mitosis, which distinguishes them from neurons.

Tumours

In otherwise healthy individuals, Schwannomas are benign tumours of the peripheral nervous system that typically manifest themselves as sporadic, single lesions on the neurological system. Individuals who have multiple schwannomas that arise from one or more parts of the peripheral nervous system are extremely rare.

Morton’s Neuroma is a benign nerve growth that develops as the outer covering of a nerve in your foot expands. It is a very frequent problem that affects people all over the world. Two bones repeatedly rubbing together causes in irritation of branches of the medial and lateral plantar nerves, which results in thickening of the skin around these nerves.

The Central Nervous System (CNS)

The Central Nervous System (CNS) is sometimes referred to as the “central processing unit” of the body because of its role in information processing. It is made up of two parts: the brain and the spinal cord.

Brain

The brain is one of the most essential, largest, and central organs of the human nervous system, and it is also the most complex. It is the central nervous system’s control unit, and it aids us in a variety of tasks such as learning new things, remembering and interpreting them, making decisions, and so on. It is contained within the skull, which provides protection on the frontal, lateral, and dorsal sides. It is believed that the human brain is made up of three major parts:

1. Forebrain: The cerebrum, hypothalamus, and thalamus are the three parts of the brain that make up the anterior region of the brain.
2. Midbrain: The Tectum and Tegmentum are the smaller and more central parts of the brainstem that make up the midbrain.
3. Hindbrain: The cerebellum, the medulla, and the Pons are all parts of the brain that make up the central region of the brain.

Brain stem

A stalk-like portion of the brain that connects our brain to our spinal cord is represented by the term “brainstem” (column of nerve tissue that runs down your spine). Because it is located near the bottom of your brain, it is considered to be a member of our central nervous system.

Our brainstem is involved in the regulation of several bodily activities, including breathing and heart rhythm. The brainstem is also responsible for maintaining your balance, coordination, and reflexes.

Spinal Cord

Located within the spine, the spinal cord is a cylindrical bundle of nerve fibres and accompanying tissues that communicate with the brain and allow communication between all parts of the body. It begins from the medulla and extends downhill in a descending direction. It is protected by a bony cage known as the vertebral column, which is bordered by membranes known as meninges. The spinal cord is responsible for the execution of spinal reflex actions as well as the transmission of nerve signals to and from the brain.

Peripheral Nervous System

A lateral section of the nervous system that arises from the central nervous system and connects different parts of the body to the CNS is known as the Peripheral Nervous System (PNS). It is via the use of peripheral nerves that we may perform both voluntary and involuntary activities.

The peripheral nervous system (PNS) is composed of two types of nerve fibres:

• Fibres of the afferent nerve – These are important for conveying messages from tissues and organs to the central nervous system (CNS).
• The efferent nerve fibres are responsible for transmitting messages from the central nervous system to the associated peripheral organ.

The peripheral nervous system is divided into the following categories:

• A neural system that controls voluntary actions in the body by sending impulses from the central nervous system (CNS) to skeletal muscle cells is known as the somatic neural system (SNS). The somatic nerves are what make up this system.
• The autonomic nervous system (ANS) is comprised of the following parts: Among its involuntary acts are the regulation of physiological functions, which is performed by the autonomic nervous system (digestion, respiration, salivation, etc.). 
• It is a self-regulating system that transmits impulses from the central nervous system to the smooth muscles and involuntary organs of the body (heart, bladder and pupil).

The autonomic nervous system can be further subdivided into the following categories:

1. Sympathetic nervous system:The sympathetic nervous system, sometimes known as the fight or flight response, is responsible for inducing the body’s fight or flight reaction. It prepares the body’s energy for demanding or energy-exhausting activities by increasing the body’s metabolic rate.
2. Parasympathetic nervous system:The parasympathetic nervous system, on the other hand, is concerned with energy conservation and preservation. In order to conserve its energy, the body sleeps and relaxes.

Conclusion

Neurons (specialised cells of the nervous system) convey messages via thin fibres known as axons and communicate with other cells by releasing chemicals known as neurotransmitters at cell-cell junctions known as synapses. Neurotransmitters are released at cell-cell junctions known as synapses. Glial cells are non-neuronal cells that maintain and nourish the nervous system’s neurons and glial tissue.

The nervous system in humans is made up of two parts: the central nervous system and the peripheral nervous system. The brain, spinal cord, and retina are all components of the human central nervous system.

The peripheral nervous system is made up of sensory neurons, clusters of neurons known as ganglia, and nerves that connect them to one another and to the central nervous system, among other things.