The Nervous System

Have you realised that you need more energy when you run or play outdoor games? Your heart also starts beating faster when you undertake strenuous activities. This is because it pumps more blood so that more food reaches your cells. You also need more oxygen and your rate of breathing increases. So who decides how much blood should be pumped and how much oxygen is needed? The answer is our nervous system. It controls all the other systems in our body. The nervous system controls your sense organs like the eyes, ears, tongue, nose and skin. They all need the nervous system to do their various jobs. Without the nervous system, you will not be able to see, hear, taste, smell or feel.

What is the Nervous System made of?

The nervous system is made up of the brain, the spinal cord and a large network of nerves. The nerves carry messages from all parts of our body, through the spinal cord and take it to the brain. The brain decides what action needs to be taken and sends the instructions to our body systems through the spinal cord and the nerves. Without the nervous system, we would not be able to control our body.

Parts of the Nervous System:

The Central Nervous System or CNS is made up of the brain and spinal cord. The rest of the nervous system is called the Peripheral Nervous System and consists of the nerves. There are 12 pairs of nerves that branch out from the brain and 31 pairs of nerves that branch out from the spinal cord.

The Brain

The brain controls everything that goes on in our body. It also stores a lot of information and can recall the information when needed. This is called Memory. The brain is like a super computer that is protected by a bony skull and has three main regions- the Cerebrum, Cerebellum and the Medulla, also known as the brain stem. The cerebrum is the largest part of our brain. It controls the memory, thoughts, learning and intelligence. It also controls our sense organs. The cerebellum controls the movements of our muscles and helps us to keep our balance. It is the back side of the brain. The medulla looks like a stem; hence it is also called the brain stem. This joins the brain to the spinal cord and helps to control actions such as circulation and breathing.

Nerves

Nerves are just like telephone wires because they carry messages between the brain and our body. There are three types of nerves: Sensory Nerves, Motor Nerves and Mixed Nerves. While Sensory Nerves carry messages to our spinal cord and brain from the sense organs, the Motor Nerves carry messages from our brain and spinal cord to muscles and glands, telling them what to do. The Mixed Nerves carry messages between the sensory nerve cells and the motor nerve cells. They are present in the spinal cord and the brain.

The Spinal Cord

The spinal cord is a thick bundle of nerves connected to the brainstem. It goes down our back and is protected by the vertebra. Its main function is to transmit information between the brain and spinal nerves. The spinal cord is also involved in some reflex activity.

Reflexes

A reflex is an emergency reaction of the nervous system to any threat, such as something hot touching our skin. It is a division of the nervous system and is called the automatic nervous system. For example, when we accidentally touch a sharp object, we withdraw our hand immediately. This is called an automatic reaction. In such cases the messages do not go to the brain, the spinal cord is able to sense the danger and take action quickly.

Sense Organs

Our five senses-, the eyes, nose, ear, tongue and skin, help us know our surroundings. Our eyes and brain work together, to make us see things by sending messages to the brain through the optic nerve. The nose has endings of nerves inside, which can detect smell. The smell messages are sent to the brain by these nerves. The tongue has tiny bumps called taste buds which contain the end of nerves that can detect the five kinds of taste: sweet, salty, sour, umami and bitter. These taste messages are sent to the brain through these nerves. The skin also has many nerve endings which send messages to the brain. These are sensitive to pain, heat, pressure and cold.