Facts about the works of  human body Parts 1: Eyes, Ears, Nose

Eyes

Eyes help us to see. Your eyes work by taking pictures of the world and sending them to your brain. Light from a thing pass through the lens in the middle of your eye. The lens centre the light onto the retina at the back of the eye. The retina transform light outline into signals that it sends to the brain. The brain changes the signals into a picture to tell you what your eyes are seeing. We need two eyes because together they help us see things properly. Each eyes gives the brain a slightly different view of something, and the brain uses those little differences to work out exactly how far away the object is. This is called depth perception helps us do things like catch a ball, shake hands or pick up a pain. In a fraction of seconds, our eyes work with the brain to tell us what we are looking at and what size, colour, texture and shape it has.

             The eyes are made up of:

Pupil: when we look at an object, the light from the objects our eye through the round black hole called pupil.

Iris: Pupil is surrounded by a coloured ring-shaped membrane called iris. Iris organize the amount of light that can enter the eye. Too much of light can hurt our eyes.

Lens: The lens of the eyes sits just behind the iris. It focuses the entering light onto the retina to form sharp, clear image of the object.

Retina: It is situated at the back of the eyeball. It is made up of many light receptors called rods and cones.  So this is how we see. When the light from the lens falls onto the retina, the nerves inside the retina turns this light into special signals and carry these to the brain. The brain then tells us what image we are looking at.

            You usually blink once every five seconds. You may not even notice you are doing it. Blinking keeps your eyes clean and moist. When you blink, your eyelid spreads tears over from the front of the eye. This stops the eyes from drying out and washes out bits of dirt and dust. Blinking also helps to stop and dirt getting into your eyes in the first place.

 

EARS: How do ears work?

            Ears help us to hear. You have two ears, one on each side of your head helps you work where sounds are coming from. For example, before crossing a road, you look and listen for cars. The sound of a car reaches one ear before the other. Your brain uses the slight difference to judge how far away the car is and check if it is safe to cross.

 

A process takes place inside your ears, which turns sound into signals to the brain. Sounds make the air vibrate, or move to and fro, and the vibrating air makes the eardrum vibrate. The eardrum is joined to set of tiny bones, called ossicles, so they vibrate too. The ossicles pass the vibrations to the tube called the cochlea. When tiny hairs inside the cochlea move, they send signals along a nerve to the brain.

            When a sound wave reach our ears, it hits the eardrum. The eardrum is a thin layer of skin inside the ear. The sound wave make the eardrum vibrate and with this, the bones behind the eardrum vibrate too. The nerves inside the ears convert these vibrations into signals that the brain can understand. The brain signals back and we understand what the sound is. Remember that your eardrum is very sensitive and fragile. It’s not a good idea to place anything in your ear. Even a little that seems safe and soft can injure your eardrum.  Sometimes, even loud noise can damage it.  The sounds that people hear most clearly are other people’s voices. That is because being able to hear other people is an important form of communication for us.

            Gymnasts balance using their ears. Inside the ear, there are three bony tubes called semi-circular canals that are filled with fluid. When the body moves, so does the fluid in these tubes. The brain uses these slight changes to sense even the smallest movement. This allows a gymnast to adjust their arms or legs in order to keep them balance.

 

NOSE

            Nose helps us to smell. You smell things when you breathe in and air passes through your nose. The inside of your nose is lined with nerve cells that sense odours in the air. The nerves cells that send messages to the brain, which then works out what the smells are. Your sense of smell is important. It can warn you of danger, for example, if you smell smoke from a fire.

            When we breathe, the air goes into our nostrils. There are many tiny hair inside the nostrils called cilia. We already know about how cilia can trap the germs and dirt and act as our bodyguards. But there is another very important function of cilia. These tiny hair are connected to nerves that send signals to the brain about the smells around us. We smell things when they release small molecules that float in the air. These molecules reach our nostrils and activate the nerves in the cilia which take the information to the brain and we know what we smell. But sometimes the sense of smell gets bored easily. When you enter a bakery, you are very aware of the smell at first but by the time you select your favourite cake, you will no longer be able to smell the different smells around you. But it will be refreshed if you give your nose a little break. Go and breathe some fresh air. Try the bakery now, it smells delicious again.