HUMAN BODY

Our nervous system needs information to create responses in order to move or react to something. We use our senses to get that information from our surrounding: hearing (ears), seight (eyes), smell (nose), taste (tongue), touch (skin).

OUR EYES

Our eye is a very complex machine, very similar to a camera.
The iris is the coloured part of the eye and it's made up of many different muscular tissues that makes the smaller or bigger according to the source of light.
The pupil is a black hole that lets the light pass into the eye. It's bigger when there is not much light and smaller when it is lighter.
The cornea protects the iris and the pupil and it is responsible for focusing the light into the eye.
The retina is the back wall of the eye and it is where the image is focused in an upside way. Then, the different cells on the retina (cones and rods) create nerve impulses that are transmitted to the optic nerve. 
The optic nerve transmits the nerve impulses to the brain where the information is interpreted.

 Here you can learn how our eye works:

It is important to check your eyes regularly in order to detect possible problems and correct them with glasses or lens. If our senses work properly our brain won't need to make an extra work. 

Here you are a video that explains the different problems of sight that we can suffer from (shortsighted, farsighted and astigmatism); enjoy it:

OUR EARS

Thanks to our sense of hearing we can detect sounds around us. It is important to have our ears clean and don't put objects inside it because we can damage different parts of them.

The main parts of the ear are:

Auditory canal is the tube where the sound travels through. At the end of the auditory canal we have the eardrum. 

The eardrum is like the membrane of a drum and when the sounds arrive here it vibrates and makes the ossicles (small bones: hammer, anvil and stirrup) move. This movement creates nerve impulses in the cochlea and this information is sent to the auditory nerve.

The auditory nerve is connected to the brain, so the nerve impulses are transmitted from this nerve to the brain. The brain receives the information and interprets it.

Here you are another video that explains how the ears work:

THE SENSE OF SMELL

 

In the air there are gasses that pass into our nose through the nasal passages. When they are detected by the olfactory cells (receptors) they create nerve impulses that are transmitted to the olfactory nerve. It sends the nerve impulses to the brain and it interprets this information.

Another video to see the nose working:

THE SENSE OF TASTE

Thanks to the taste we can detect many different flavours. In our tongue there are different bumps called taste buds that mix the chemical substances in the food with the saliva. There are some nerves in our tongue called the gustatory nerves that receive the nerve impulses and send the information to the brain to interpret it. 

In the tongue there are different zones where we can detect sweet, salty, sour and bitter food.