Can you feel the hotness of a cup of tea? Can you feel the warm air and cold air? How do you do that? If you are not familiar with the science behind it, it’s time to know now!
Sense organs are those organs interconnected to the sensory nervous system. It is nothing but a part of the nervous system responsible for processing sensory information.
FACT: Sense organs respond to external stimuli by conveying impulses to the sensory nervous system.
In the following passages, we will discuss different kinds of sense organs that a human body contains in detail while having a good look at some of its related concepts.
This is an important chapter that has a lot of weightage in the CBSE Class 12 Term 2 exams.
Sense organs – Definition
A simple definition of sense organs would be a bodily structure that could receive stimulus and be affected. It could easily initiate excitation of associated sensory nerve fibers. This behavior causes some effects on the central nervous system, where they are interpreted as corresponding sensations receptors.
What are the sense organs?
These are referred to as specialized organs capable of helping us perceive this world. Sense organs act as an integral part of our lives, and it is one of the only ways that could enable us to perceive our environment.
These sense organs provide us with the required data to interpret through a network of nerves and various other organs in response to multiple physical phenomena.
Given below are the five most fundamental sense organs situated in our body:
All the above-mentioned sensory organs are provided with receptors that could easily relay all types of information through the sensory neurons to appropriate places within the nervous system.
These receptors are categorized into two categories: general receptors and the other is special receptors. The general receptors are contained throughout the body, whereas the special receptors include chemoreceptors, photoreceptors, and mechanoreceptors.
Five sense organs
As mentioned earlier, we have five sense organs capable of receiving and relaying sensory information to our brain. This helps provide an organism with an essential amount of information crucial for perception. The following paragraphs explain each of the sense organs stated above.
Eyes – Ophthalmoception (Sight)
Eyes are the visual sensory organs in our bodies and are seen as sensitive to bright or light images. The colour of eyes varies from person to person based on the melanin percentage contained in our body.
The pupil’s diameter is controlled by the iris present in the eyes. Iris is a colored part that directly affects the amount of light that enters the eyes. The vitreous body lies behind the lens of the eyes and is filled with gelatinous material. This is called the vitreous humor.
This structure is very helpful in deciding how the shape of the eyeball should be and can also easily transmit light to the eyeball on its very back. This is the place where the retina is being found.
Fun fact: Your eyes can distinguish approximately 10 million different colors.
The retina consists of photoreceptors that help detect light. Two kinds of cells could perform functions different from each other. Those are rods and cones.
- Rods: Rods are sensors that can function in low light. Rods are found on the edges of the retina in the eye. Other than just that, they could also be helpful in peripheral vision.
- Cones: Cones are another type of retinal cell capable of working better while in bright light. This helps detect fine details and colours, and other more important features. There are three different types of cones to detect three colours of light: red, blue, and green. Moreover, colour blindness is a deficiency when any of the types mentioned above is missing.
Fun fact: Ommatophobia is a fear of the eyes.
Tongue – Gustaoception (Taste)
The tongue is one of the five sense organs. It helps us perceive various kinds of flavors and tastes. The taste buds are contained on the tongue between the papillae, which helps in sensing various tastes.
Do you know?: The tongue is made up of eight muscles.
The tasting sense and smelling sense partner up and perform together. If a person cannot smell something, neither could he taste it. The tasting sense can also be referred to as gustaoception. Taste buds on the tongue also contain chemoreceptors that will work the same as chemoreceptors in the nasal cavity.
Additionally, the chemoreceptors present in the nose could detect any smell. In contrast, there are only four different kinds of taste buds, and each can detect various kinds of tastes such as sweetness, saltiness, sourness, and bitterness.
Fun fact: Those bumps on your tongue are not taste buds. There are taste buds all over the tongue. There are thousands of taste buds on a person’s tongue.
Nose – Olfalcoception (Smell)
Our noses are olfactory organs, and the olfactory system present in our noses helps us perceive different kinds of smells. Smelling sense doesn’t just stop there. It also helps us taste different kinds of foods. This can also be termed as olfaction.
On one of the ends, olfactory cells contain cilia which help project into the nasal cavity, while on the second end, olfactory nerve fibres are present.
While breathing in, the nasal cavity sucks air in. These cells mainly consist of protein receptors that could detect precise changes in chemicals. This is why these cells are chemoreceptors. These chemicals are bound to the cilia that could eventually conduct a nerve impulse sent to the brain.
Do you know?: Your nose regulates the temperature of your breath. Your nose protects you through smell.
After this, the brain translates them into forms of meaningful smells. Furthermore, during cold, our body generates mucus that could block the smell. So, this is why our foods taste bland when we try to eat while having a cold or fever.
Ears – Audioception (Hearing)
Ears are rightly considered as the auditory sense organ of the body. Ears help us perceive sounds. The process behind how we could hear sounds includes the detection of vibrations, and that is how any living creature in this world can hear sounds. This is called hearing or audioception.
Do you know?: Ears are always working. Your ears never stop hearing even while you’re asleep.
Ears are divided into three sections. They are the inner ear, middle ear, and outer ear. All the sounds that are occurring in this world are vibrations. The outer ear can capture those vibrations and transfer them into ear canals. This is where our brain understands the frequency of those vibrations, changes them into meaningful sounds, and helps us hear them in the correct form. Other than just hearing, it is fundamental for us to balance our equilibrium.
Skin – Tactioception (Touch)
Comparing all other sense organs, skin is seen as the largest of them all. Skin can be seen as a touching sense. This can also be called tactioception.
Fun fact: The average person’s skin covers an area of 2 square metres. Skin accounts for about 15% of your body weight.
The skin contained in the body consists of general receptors that could feel touch, temperature, pressure, pain, etc. These are present everywhere on the skin and are highly capable of generating an impulse. When activated, it has been sent to the spinal cord and then eventually to the brain.
Other sense organs
Apart from the ones mentioned above, two more sensory organs could help orient us with the world:
- Vestibular system:
This system can act as one kind of sensory system for our body. It plays a crucial role in transmitting information to the brain regarding the head position, motion, and spatial orientation. This system involves motor functions and assists in the following functions:
- Maintaining the balance of our bodies.
- Maintaining our body posture.
- Identifying the body’s orientation and posture in accordance with the environment.
- Stabilising our head as well as our body during any movement.
Therefore, this system is very fundamental for normal moments and equilibrium.
- Proprioception system
This system involves consciousness and unconsciousness of the joint position. The proprioception system helps our body identify the muscles, limbs, and joints located in the three-dimensional space, as well as the direction in which its movement is in relation to the body. The following are some of the actions made with the assistance of this system:
- Touching nose with closed eyes.
- Balancing on a single leg.
- Walking without looking exactly at our legs.
- Putting food in our mouth without actually looking at our mouth or hands.
This is an important chapter while preparing for NEET Biology.
Frequently Asked Questions on Sense Organs