How does human brain work?

All animals that we can think of have a brain, be it birds, sea animals, elephants, frogs, etc. But what distinguishes the “Human Brain” from the rest of the animals around us although it is not the largest? It can perform several activities, separately or simultaneously. It gives us emotions; reasoning, thought, power to control our muscles, the five different senses and even the ability to dream. It is truly an amazing organ. It is the most complex organ of the human body acting as a hub for about 50-100 billion neurons which are connected to each by nodes called Synapses. The brain, spinal cord and the peripheral nerves together form the Central Nervous System.


The primary functions of the brain are:

  • It controls the physical actions which involve the movement of muscle parts
  • It maintains the blood pressure, heart beat, body temperature and breathing
  • It receives and processes the data sent from the sense organs to make us aware of the environment around us.
  • It gives us the ability to think, reason and dream about every abstract matter around us. It also lets us feel emotions.


Although we evolved from the primates, the human skull structure saw a drastic change as it was noticed that comparing a primate’s and a human’s brain, the primate skull was bulged toward the inside whereas the human brain did not have these inner facing protrusions. This gave more volume to the skull enabling it to support a larger brain. The inner bulges of a primate’s skull were evolved to place the jaw muscles. Therefore jaw strength was sacrificed to make room for intelligence.


A chimpanzee brain

A chimpanzee brain

The human brain containing a jelly like mass of tissue called the “Grey Matter” which is the cell body made of neurons and “White Matter” which is the branching network of the thread like roots of the neurons called “Tendrils”, weighing about1.4 kilograms. The neurons present in the central nervous system carry messages through electrochemical charges with the help of sodium, potassium or chloride ions. We can symbolise them as the wiring system of the human body. A certain class of cells called the “Glial Cells” also exist in the brain matter. They function by amplifying the neuron signals. More Glial cells imply the better mental calculation ability of the person. Study of the human brain is called Neuroscience or Neurobiology. The brain is categorized into different parts each of which co-ordinates specific functions.



Anatomy of human brain

The brain is divided into two hemispheres along a longitudinal axis. Most people generally believe that the right hemisphere of the brain is more on the creative and emotional side where the left side deals with logical, reasoning and memory. Although this is true on an elementary level, it is much more complicated than that. Coming on to the parts of the brain are:

 1.      Brain Stem:

The brain stem consists of the medulla (the upper end of the spinal cord), pons and the midbrain. The brain stem controls the involuntary functions like heartbeat, reflexes, limb movements, digestion and urination processes.

 2.      Cerebellum:

The cerebellum analyses the information received from the vestibular system to indicate the position and movement to coordinate the limb movement function of the brain stem.

 3.      Hypothalamus and Pituitary Gland:

The hypothalamus and the pituitary gland are responsible for visceral functions, maintaining body temperature and various behavioural responses like aggression, pleasure, hunger etc. the pituitary gland is also responsible for releasing various hormones that are responsible for bodily functions.

 4.      Cerebrum:

The cerebrum is the ‘Control Room’ of all the sense organs. It also performs all activities of the motor neurons and controls emotions. It also holds memories by creating millions of new neuron connections and provokes thought process. The cerebrum is the largest and most evolutionarily recent part of the brain.



A stimulus is anything that provokes the sense organs causing the necessary reaction. When an organ comes across a stimulus, the sensory nerves pass on a signal through electrochemical discharges through the tendrils of the neuron. This signal on reaching the brain activates the cerebrum or the cerebellum discharging a response which goes back through the same way to the sense organs which react accordingly. All this processing and responding takes place in a fraction of a second.


Certain signals sent by the neurons stimulate the discharge of some neurochemicals like glutamate, dopamine, acetylcholine, noradrenalin, serotonin and endorphins. These neurochemicals pass on the signals from the neurons to the collection centres called receptors in the brain cells to process the information. These chemicals must be produced in a perfect balance to perform its exact task. The deficiencies of these neurochemicals result in degenerative diseases. The deficiency of dopamine causes leads to Parkinson’s disease. Deficiency of serotonin causes depression and acetylcholine leads to Alzheimer’s disease.



The brain structure is partly dependant on the genes inherited from the parents but largely dependent on experience. Recently neurobiologists have discovered that the brain cells are born fairly regularly throughout our lives. This process is known as “Neurogenesis”. During certain periods of our lives the brain undergoes bursts of growth. This occurs at the first two to three years, during puberty and again during early adulthood. The ageing of the brain also depends on the lifestyle choices that we make. For example excessive drinking affects the nervous system which causes paralysis and brain damage since damage to nerve cells is permanent and not fixable. The right diet keeps the brain healthy.  It is also important to exercise our brain from time to time to keep the signals running smoothly. This can be done by reading, problem solving, undertaking creative hobbies etc.

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