Road safety

Many victims of traffic accidents in cities and villages are children. The main reasons are: crossing the street unsafely, riding a bicycle without wearing a helmet, and not wearing a seatbelt in the car.

In some cases, the consequences of these accidents are very serious. The spinal cord and the brain can be damaged. Spinal cord injuries can cause paralysis in different parts of the body, and brain injuries can affect many activities such as thinking, talking, moving, etc.

In order to be safe and avoid these types of accidents, we always need to be careful when we cross the road at pedestrian crossings or traffic lights. In addition, we always need to wear bicycle helmets and seatbelts.

It is estimated that the proper use of a bicycle helmet can reduce the risk of head injury by 70 %.

What is sensitivity?

Through sensitivity, we respond to changes in the external environment. These changes are called stimuli.

Look at these examples:

• If the Sun is too bright, we respond by shading our eyes.

• If we see a large rock falling towards us, we respond by moving away.

• If we walk into a room and there is a bad smell, we respond by holding our nose or leaving the room.

How does sensitivity work?

If somebody throws a ball to us, we respond by trying to catch it. In order for this to happen, various organs and systems are involved.

• Sense organs capture information from the environment. Sense organs have groups of specialized cells, called receptors, which are sensitive to stimuli.

• The nervous system controls the function of sensitivity. First, the nerves carry information from the sense organs to the brain. The brain receives and interprets the information and decides how we should respond. Finally, the nerves carry responses from the brain to the muscles.

• The locomotor system is made up of the muscular system and the skeletal system. Muscles receive orders from the brain and work with bones to make the body move.

Internal coordination

Many processes are occurring inside our body at all times, for example, digestion and blood circulation. These processes are coordinated in order for the body to function properly.

This is called internal coordination, and it is part of the function of sensitivity. The nervous system is responsible for internal coordination.

The sense organs capture information from the environment and send it to the brain through the nerves.

Eyes and sight

The eyes are the sense organs of sight. They detect light so we can see shapes and colours, and estimate distances.

The information captured by receptors in the retina travels to the brain through the optic nerve. The brain receives and interprets this information.

Ears and hearing

The ears are the sense organs of hearing. They detect sounds and their properties, and where these sounds come from.

The information captured by receptors in the cochlea travels to the brain through the auditory nerve. The brain receives and interprets this information.

The tongue and taste

The tongue is the sense organ of taste. It detects different flavours.

The information captured by receptors in the taste buds travels to the brain through the taste nerves. The brain receives and interprets this information.

Nervous tissue under a microscope. 

Neurons

Nervous tissue consists of nerve cells or neurons. These are grouped together to form nerves. Neurons have three parts:

• The body, which is the widest part of the neuron. The other parts reach out from the body like branches.

• Dendrites, which receive messages from the sense organs or other neurons.

• The axon, which transmits messages to other neurons.