The nervous system

All parts of the nervous system are interrelated. The nervous system can be separated into the following divisions and subdivisions:

The central nervous system includes all the nerves in the brain and spinal cord, and it contains the majority of the body’s neurons. Some of the very simplest stimulus-response reflexes are carried out within the spinal cord. The peripheral nervous system consists of the nerves leading from the brain and spinal cord to the other parts of the body. The peripheral nervous system is subdivided into the somatic system and the autonomic system.

The nerves of the somatic system transmit information about external

stimulation from skin, muscles and joints to the central nervous system; they make us feel pain, pressure and temperature variations. Nerves of the somatic system also carry impulses from the central nervous system back to the body parts, there they start action.

The nerves of the autonomic system run to and from the internal organs regulating such processes as respiration, heart rate, and digestion. It took its name from the fact that many of the activities that it controls are autonomous, or self-regulating – such as digestion and circulation, which continue even when a person is asleep or unconscious.

The brain

Your body’s personal computer

• is soft and looks like a cauliflower;

• consists of over ten billion nerve cells;

• is pink/ grey colour;

• has two distinct halves;

• control every aspect of your physical and mental life.

The human brain has 3 main functions:

1. it controls the body. It’s a difficult task because every part of the body needs food, blood, heat and oxygen;

2. it stores data in the form of memories, which can then be taken if necessary;

3. it creates thoughts, dreams, ideas, emotions, moods.

The brain works by receiving and sending signals at fast speed. Let’s take a simple example. You’re visiting a friend and you pick up a cup of tea. What happens? Well, first the receptor cells in your hand collect information about how big/ heavy/ hot the cup is. All this information is sent to the brain by nerves called sensory neurons. They exist in very part of the body and pass signals from one to the next like electricity. So the information about the cup is in your brain. Next, it is processed. The brain does this by using its memory of the same experiences in the past to make decisions. What decisions? Well, perhaps the cup is very hot – dangerously hot. In this case the brain tells your hand to put down or even drop the cup. Instructions like these travel back to the hand along a different set of nerves called motor neurons. The last motor neuron in the chain is connected to a muscle. The signal arrives – the muscle contracts - your hand puts down (or drops) the cup.

Thousands of signals are received and sent every second – signals about what you see, touch, hear, feel, say, taste, remember.

While you are asleep it makes sure that the internal organs which you can not control (the liver, kidneys, heart) continue to work. It produces dreams. No one exactly knows why we dream, but there are two main theories. One is that we all have fears and fantasies which are difficult to fully understand and express while we are awake. The result? Our brain explores them at night. While we are asleep, our brains store information about the previous day. In other words, they file what happen, who we met, what people said to us, the emotions we felt, comparing it with the information already in the memory.

The brain is divided into several different areas, each of which has a specific job – controlling vision, speech, thought or memory. There is some difference between the left and the right side (hemispheres) of the brain.

The left brain controls logic, numbers, facts, analysis, the movements of the right-hand side of the body. The right brain controls emotions, music, dreams, imagination, the movements of the left-hand side of the body. For most people, the left half of the brain is more powerful or dominant than the right. But for creative artists, painters, writers, composers the opposite is true.