The brain is the most amazing organ in our body that simulates the activities of a computer when performing a task. It controls the important functions of our body including breathing, heart function, blood pressure, physical movements, dreaming, reasoning and experiencing emotions.
It is fascinating that how such a small organ like our brain which is of the size of a cauliflower’s head controls our day-to-day life activities. The brain, spinal cord and the peripheral nerves of our body together regulate all the conscious and unconscious aspects of functioning.
What are Neurons?
The brain constitutes billions of nerves that communicate with each other through means of certain chemical transmitters. The cells of the nerves are called neurons that send out signals to and from other neurons of the body.
An action or stimulus is generated by the signals that are sent to and from different neurons located in the body and the brain. They are essentially like the wires of the computer that process and send information for the appropriate functioning.
Parts of the Neurons
- Soma – It is the body of the neuron cell that contains essential components like DNA, ribosomes and mitochondria that carry the life of the cell.
- Axon – It is a long cable projection of the cell that carries the messages from one neuron to another to carry out an action or stimuli.
- Dendrites – They are the nerve endings with small branches which create the connections to other neurons. They can be located the both the ends of the cell
- Myelin Sheath – It is a fatty layer that covers the axon and effectively increases the transmission speed through the axon.
- Axon Terminal – They contain synapses where chemicals called neurotransmitters are generated to pass a signal from one neuron to another.
Neurons come in many size and shapes in accordance with the function generated by them. The neurons in the brain are smaller compared to other where it can extend for longer length like in the arms.
- Sensory Neurons – They are generally unipolar and have dendrites at both ends with a cell body in the center joined by a long axon. They carry signals from periphery external parts of the body to the central nervous system.
- Motor Neurons – Suggested by its name, it controls muscle movements. They contain a cell body with an axon connected to a dendrite on the other end. They send out signals from the central nervous system to the external parts like the muscle or skin of the body to generate some reaction.
- Interneurons – They coordinate movements between the sensory and motor neurons. They are generally bi-polar that have two axons wherein when axon connects to the central nervous system and the other to the specific body part. Their job is to monitor and link neurons within the brain, spinal cord and external body parts.
For instance, let’s take a simple movement of the knee reaction. When you tap your knee with some object, a signal from the sensory neuron is passed onto the spinal cord. The sensory neuron then passes on information to the motor neurons of the corresponding leg muscle. The motor neuron then generates a movement in the muscle to contract.
The response if that of a jerk that happens in a matter of seconds through this process. There are many wired reflexes like this controlled in a similar way. But more complex tasks involve the brain also to play its role and the neurons in the brain pass the signals to others.
Even though the neurons have the capability to repair and regenerate in the event of damages; there are still a lot of adverse conditions without proper functioning of the neurons. Some of them are hereditary and some lead to overall loss of productivity with certain functions of the body difficult to perform.
Disorders of the neuron lead to loss of the computational power of the brain.
- Alzheimer’s disease – It involves deterioration of the cognitive ability and is a neurodegenerative condition with day-to-day activities coming to all time low. The very first symptom of this disease is constant memory loss progressing to more levels of forgetfulness. With more progress the person also experiences significant intellectual impairment that can extend to language, movements, recognition and decision-making functions.
- Parkinson’s disease – Also another degenerative disease of the central nervous system that deters motor movements and speech. It involves symptoms of tremors caused by muscle rigidity and reducing physical movement. This happens due to a massive reduction in the stimulation process of the brain to perform the necessary action. It can also lead to slow cognitive capabilities and language problems with bad speech.
- Myasthenia Gravis – It leads to muscle weakness and causes overall fatigue when doing simple tasks. This happens due to blockage of connection near the neurons of the muscular junction that constrain the stimulation process of the muscle.
- Charcot-Marie-Tooth Disease(CMD) – It is a hereditary disorder of nerves with damage of the touch function and muscle tissue more in the feet and legs. As it progresses, it can also pass on to other parts of the body like arms and hands. This is an incurable and inherited disease.
- Multiple Sclerosis – The myelin sheath effectively transmits signals from one neuron to another. Due to the loss of this myelin, it leads to bad conduction of signals and the nerve weakens gradually leading to the problem of multiple sclerosis. It leads to severe attacks including physical, mental or psychological problems.