Why do we need sense organs

The 5 sense organs: skin, eye, ear, nose and mouth

The sense organs from the perspective of biology are dealt with in this section. First of all, we will tell you what a sense organ is and which organs are so called. In addition, we will show you what performance these sense organs accomplish.

Let's start with a supposedly very simple question: What is a sense organ? Well, this is an organ that can capture information in the form of stimuli. These Stimuli are conducted by nerves into the brain and processed there so that people become "aware", i.e. they notice the stimuli. Man has five sense organs: Skin, eyes, ear, nose and mouth. Even if the properties of these organs are known to many, we want to go into their functions again here.

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The skin - the largest sensory organ

The skin isn't just that largest sense organ of humans, but also the largest human organ at all. The skin has several functions:

  • The skin provides the "surface"and prevents our blood from leaking out of the body. This case only occurs with wounds, where the body tries to close the wounds as quickly as possible and" repair "the damage.
  • The skin is also used for Perception of our surroundings. This is how we feel when rain is pounding down on us or a cold wind is blowing. We also feel touched and feel when we have been wounded.
  • Far less known is that the skin also breathes. The so-called Skin breathing helps supply our bodies with oxygen. However, skin respiration is very weak compared to normal respiration: Humans only perform around 1% of the air exchange through the skin.


Everyone has their own individual skin structure. The police also make use of this. So you can use Fingerprints determine whether a person has touched an object with their hand. Because a direct touch of the hand - without gloves - leaves traces on an object. These traces can be compared with the fingerprints of people. Each person has a unique fingerprint, even identical twins have different fingerprints.

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The eye / The eyes

What the eyes are good for should be clear to everyone: To see. For this reason, the eyes are also part of the human sense organs. However, many people know far less about how they work, which is why we would like to list some important features here:

  • The eye reacts to optical stimuli and can perceive light with a wavelength of around 380 nm to 780 nm. To whom the numbers mean nothing: The Wavelengths define the colors of lightthat we perceive. The values ​​just mentioned represent the colors of light that a healthy person can perceive.
  • There is an outer, middle and inner eye skin. The outer skin of the eye contains the dermis to which the Eye muscles attack to move the eye. The choroid (rich in blood vessels), the ciliary body (suspension of the eye lens and accommodation) and the Iris (Iris), which forms the pupil. To the inner eye skin (retina) one counts the light sensory cells. There are no light sensory cells where the optic nerve leaves the eye. The area of ​​the field of vision that corresponds to this point is called the Blind spot. The point of sharpest vision is the yellow spot.
  • In the retina stand about 130 million visual cells close to each other. These are divided into rods and suppositories. The rods provide a black-and-white image and enable you to see at dusk. Colors are perceived with the cones.
  • The sensory cells are stimulated to different degrees by the light falling on the eyes. This information is provided via the Optic nerve forwarded to the brain and processed there.

The ear (s)

The ear, better said, the two ears are used to hear sounds. In principle, the following applies: the younger a person is, the better they hear. This is why many older people often have to speak much louder or they turn the television or radio much louder. But how does this sense organ actually work? Well, this is how hearing works:

  • Take the ears Sound waves true. When these sound waves reach the ear, they are conducted from the auricle into the ear canal. There they meet that eardrumwhich starts to vibrate. The first of the three ossicles has grown firmly to the eardrum and therefore has to move with it.
  • The hammer hits the anvil and this on the stirrup. This amplifies the sound and transfers it to a special skin that closes the middle ear from the inner ear. The fluid in the ear begins to "vibrate". The auditory cells are located in the snail. These send the stimuli to the brain via a so-called auditory nerve so that we can perceive them as noises.
  • At a young age, the human ear hears frequencies between 16 Hertz and around 20,000 Hertz. If the person grows up slowly, the maximum decreases audible frequency. This depends on genetic factors, but also on the way of life. Anyone who goes to the disco every day increases their risk of needing a hearing aid considerably.

Mouth and nose

The tongue in your mouth tells you whether you like lunch or not. This has so-called "Fields of taste", with which different tastes can be perceived. For example, part of the tongue is used to perceive bitter tastes, while another is used for sour tastes. A third area is used to identify salty foods and a fourth area for sweet tastes.

The nose, on the other hand, has two extensive functions. On the one hand, we can breathe through them, as well as through the mouth. In particular, cold air is first warmed up and moistened when inhaled through the nose. The second function of the nose is to perceive smells. So you can smell very quickly whether the person sitting next to you at school or your colleague from the office is wearing fresh clothes or has recently taken a shower.

If you want to find out more about the nose, click on our article "The nose".

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