Nervous tissue makes up the nervous system in the human body. It allows the system to link the brain with the rest of the body and transmit and receive messages between them. The central nervous system controls movement, thought, sensation, and emotion, while the peripheral nervous system conveys information to and from the central nervous system. The anatomy of nervous tissue includes various types of cells, such as neurons and neuroglia. In addition to transmitting electrical signals, neurons are protected and supported by neuroglia. An axon and dendrites make up the neuron’s cell body. Dendrites project from the cell body and receive information from other neurons. The nucleus and cytoplasm are found in the cell body.

Neuron Structure

The nervous tissue in the brain and spinal cord contains neurons, which are nerve cells. Electrical signals are sent and received by them. Neurons have three parts: dendrites, axons, and a cell body. Cell bodies contain the nucleus and different organelles. Cell bodies are branched and have dendrites that resemble trees. Neural contact occurs at the dendrites.  Each neuron has an axon, which carries signals between it and other neurons. Axons allow communication and stimulation in the brain. There are billions of neurons in the human brain, each with a unique structure.

• Brain regions communicate with one another using neurons. Cells in the body use neurons for communication. 
• Nerve cells fall into two main categories: sensory neurons and motor neurons. The spinal cord and brain receive communication from sensory neurons in other parts of the body. Muscle contraction and relaxation are controlled by motor neurons.
• Genetics and environment determine the structure of neurons. Neurons’ axons, dendrites, and cell bodies are all controlled by genes. In addition to determining how much oxygen and nutrients are available to the neuron, the environment is also a factor in shaping its development.

Dendrites and Axons

In the anatomy of nervous tissue, an axon is the long projection of a nerve cell that maintains communication with other parts of the body. A component of neuronal branches is a dendrite that receives information from the neighbouring neurons. 

Neurons contain many tiny spines that transmit messages throughout the body, and these extensions form their cell bodies. Neurotransmitters are released from these spines into the synapse.

• Cells receive information from each other primarily via dendrites. These connect the neuron body to its dendrite. 
• Arborisation is the process of extending these dendrites outward. With each branch having a specialised function, different parts of the brain are able to communicate with each other.
• These protrusions are known as dendritic spines and occur along dendritic lengths. Learning and memory are mediated by spinal cord activity. It is believed that they serve as sites for the formation and strengthening of synapses.
• Signals are transmitted away from the cell body by axons, which are the long extensions of a nerve cell. Neurons use these fibres to transmit electrical impulses throughout the nervous system.

Synapses

Synapses form when two neurons come together. Neurotransmitters are released at these junctions, binding to receptors on the dendrites of receiving neurons. Consequently, the receiver neuron receives a signal transmitted up its axon.

• Myelin is a layer of insulating (or protective) material surrounding nerves in your brain and spinal cord. 
• This layer consists mostly of proteins and fat.
• A layer of myelin sheath protects nerve cells and speeds up the transmission of signals.

Anatomical Divisions of the Nervous System

The brain and spinal cord comprise the Central Nervous System (CNS). Nerve fibres that leave the central nervous system and pass through the peripheral nervous system make up the peripheral nervous system (PNS). 

The CNS is composed of the mind and spinal cord, whereas the PNS comprises the cranial nerves and the sympathetic and parasympathetic branches of the autonomic senses.

Action Potentials

The action potential is generated by the depolarisation of the plasma membrane. An action potential consists of three parts:

• Depolarisation phase: This is where the membrane potential changes from a hyperpolarized state to a polarised state.
• Repolarization phase: This occurs after the membrane has been depolarised. The membrane returns to its original hyperpolarized state.
• Resting phase: This is the period between the depolarisation and repolarisation phases.

Disorders of the Nervous System

Epilepsy

Epilepsy is a neurological disorder that causes seizures. Seizures are caused by the excessive firing of neurons in the brain. The symptoms include:

• Sudden muscle contractions
• Loss of consciousness
• Sensory disturbances
• Headaches
• Confusion
• Memory problems
• Personality changes
• Death

Epilepsy can be categorised into:

• Generalised tonic-clonic (grand mal)
• Partial
• Focal
• Myoclonic 
• Absence
• Juvenile myoclonic
• Psychogenic

Parkinson’s Disease

A progressive, chronic illness, Parkinson’s disease causes tremors, rigidity, bradykinesia, and instability in the body. This condition worsens over time as it progresses. These are some of the possible symptoms people may experience: 

• Hallucinations
• Anxiety
• Sleep disorders
• Cognitive impairment

Multiple Sclerosis

The central nervous system is affected by multiple sclerosis, which is an autoimmune disorder that progresses over time. In addition to experiencing sexual dysfunction, affected individuals experience the following symptoms: 

• Fatigue
• Numbness
• Vision problems
• Tremors
• Walking difficulties

Huntington’s Disease

Patients with Huntington’s disease suffer from: 

• Jerky involuntary movements
• Uncontrolled muscle spasms
• Memory loss
• Early death

HTT, a gene that causes nerve damage in the brain, causes nerve cells in the brain to die. As a result of this damage, the individual loses coordination, has speech problems, develops depression, and eventually dies.

Conclusion

Learning about the anatomical divisions of nervous tissue can help us understand how the nervous system works. The nervous system is in charge of all of our automatic functions, such as breathing and waking up. It is also responsible for our bodily and emotional well-being. This mechanism is always in operation and is extremely vital.