Sense Organs: Have you ever wondered how a human body feels senses? How do we connect with the outside world? We perceive the external world around us through sensory organs. Sense organs respond to external stimuli by conveying impulses to the sensory nervous system. The sense organs definition states that they are specialised organs that help to perceive the world around us. These sense organs are an important part of the human body and help in experiencing the reality of the surroundings.

The 5 sense organs – namely sight, hearing, touch, taste and smell – are known, but the latest studies acknowledge that there are several more. An understanding of the 5 sense organs is useful for our day to day lives. This article provides detailed information about the five sense organs including their classification, function and more. Read on to learn about five sense organs in detail.

Sense Organs: Definition, Classification, Functions

The organs which enable the human body to perceive and respond to the surrounding environment are known as the sense organs of the body.There are mainly five sensory organs in a human body.

below is the list of the sense organs’ name:

• Eye (to see)

• Ear (to hear)

• Tongue (to taste)

• Nose (to smell)

• Skin (to touch). 

Types of Sense Organs

The 5 sense organs of the human body are the eyes, ears, tongue, nose, and skin.

Sense Organ: Eyes

The eyes are specialised sense organs that help the human body to detect light and receive visual images. A human body has a pair of eyes. The eyes are the visual sensory organs in our body that are sensitive to light images. Eyes vary in colour depending on the amount of melanin present in our bodies. It helps in the sense of sight by detecting and focussing the light reflected from objects to form their images.

The iris is the coloured part of the eye that controls the size and diameter of the pupil. It directly affects the amount of light entering the eyes. Behind the lens of the eye lies the vitreous body, which is filled with a gelatinous material called the vitreous humour. This substance gives shape to the eyeball and also transmits light to the retina at the back of the eyeball. The main components of the human eye are the cornea, iris, pupil, lens, optic nerve, and retina. Let us look at the functions of each of these parts in an eye one by one.    

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• Retina

The retina is a thin layer of tissue that is located near the optic nerve. The function of the retina is to receive light from the lens and transform it into neural signals and transmit them to the brain for identifying the visuals. Rods and Cones are the two photoreceptors that are present in the retina that detects light.

• Rods

The cells which are responsible to perform in low light levels are called rods. Rod cannot detect colours.

• Cones

The cells which are stimulated in bright light are called cones. They are photoreceptor cells. Cones are responsible for detecting colours.

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Sense Organ: Ear

The ear is a  human organ that is responsible for hearing senses and maintaining body balance. The ear is mainly divided into three parts- the outer ear, the middle ear, and the inner ear. A human body has a pair of ears.

Outer ear	The outer ear consists of a pinna and ear canal. It is the visible part of the ear.
Middle ear	The middle ear consists of three tiny bones together called ossicles. These three bones are malleus, incus, and stapes.
Inner ear	The inner ear is also known as the labyrinth of the ear. It is located at the end of the ear. This part of the ear comprises two functional parts: the cochlea and vestibular system. The mechanoreceptors respond to sense hearing and balance in the inner ear.

Sence Organ: Tongue

A tongue is a muscular organ of the human body. It is essential for chewing and swallowing food as a part of the digestive system as well as for speech. The tongue is the main organ of taste. The small bumps on the upper layer of the tongue are called papillae. Papillae are of different types like the circumvallate papillae and fungiform papillae which contain taste buds. The taste buds are a collection of sensory cells that connect to the brain. There are four common tastes: sweet, sour, bitter, and salty.

Sense Organ: Nose

The nose is a vital organ of the human body which is responsible for the sense of smell. It is also the first organ that helps in the process of respiration. It is the gateway through which air enters the human body. It is also known as the olfactory organ. It completes the process of purification of air by filtering, warming, and moistening it.

The nose has two cavities that are parted by a wall of cartilage called the spectrum. Nostrils are the external opening of the nose. The vestibule is the section that is within and above each nostril. Chemoreceptors contain olfactory receptors which are found in the nose and help in detecting smell.

Sense Organ: Skin

Skin is one of the crucial sense organs of the human body. It is also the largest sense organ of the human body. Receptors that can sense touch, temperature, and pressure, can be found on the skin. It is a soft fleshy surface, and the upper layer is covered with hair. It is like a protecting shield between the human body and the exterior environment. The colour and thickness of skin may differ in various parts of the human body. 

The skin has three layers: epidermis, dermis, and hypodermis.

Epidermis	The outermost layer of the skin is called the epidermis.
Dermis	This is the second layer which is below the epidermis.
Hypodermis	The layer below the dermis is called the hypodermis.

Other Sense Organs Name:

1. Vestibular System

The Vestibular system is a sensory system that contributes to providing a sense of balance and spatial orientation that coordinates movement with balance in a human body. It has two components: the semicircular canals that specify the rotational movements and otoliths that specify the linear accelerations, and it also provides the sense of balance and the information about the body position that allows rapid movements.

2. Proprioceptive System

The Proprioceptive system provides the sense that indicates a human body to control force and pressure. The location of this system is the muscles and joints. It is a connector between sensory receptors that provide information to the body and the nervous system. Sensory receptors are found in the skin, joints, and muscles of the human body.

Functions of Sense Organs

Sense organs and their functions play a vital role in the human body. The different functions of sense organs are given below:

Functions of Eyes

1. The eye provides the vision to human beings to see and identify an object around their surroundings.
2. Human beings possess different eye colours based on the amount of melanin.

Functions of Ears

1. Hearing is the main function of the ears. It helps us to perceive sound.
2. It allows for maintaining the balance of the body.

Functions of Tongue

1. It is involved in sensing taste with the help of different taste buds.
2. It works as a digestive organ by helping in the chewing and swallowing process.
3. It also facilitates speech.

Functions of Nose

1. It is an olfactory organ that perceives different smells.
2. It helps in breathing.

Functions of Skin

1. It protects us from injuries, cold, heat, harmful effects of UV radiation, and excessive loss of protein. It also helps in sensing pain and touch.
2. It helps in the formation of vitamin D from the sun.

Sense Organs : Coordination of Sense Organs with Nervous System

Have you ever considered how you feel when an object is hot or cold or how do you perceive the wonders of nature? even how do we communicate with each other? or how do we get the odour? So here is the answer, the different sensory organs of our body detect the type of changes in the environment through cranial and spinal nerves.

There are different types of sensory receptor cells like photoreceptors, chemoreceptors, thermoreceptors, and mechanoreceptors which are present in sensory organs that transmit sensory information from the sensory organs to the central nervous system. In the central nervous system, all the inputs are processed and analysed. Then the signals are sent to the sensory cortices in the brain where signals are processed and perceived.

This is the process through which sense organs and nervous systems coordinate with each other which in turn, helps the human body to sense the changes in the surrounding environment.

Sensory Receptors

Sensory receptors are specific nerve cells that are specialized to receive a particular kind of stimuli. It detects changes in the internal or external environment by developing a nerve impulse. The different types of sensory receptors that respond to a specific type of stimuli are:

1. Mechanoreceptors: The mechanoreceptors respond to forces and movements. They are found in the skin to sense touch and in the ear to sense hearing and balance.
2. Thermoreceptors: The thermoreceptors respond to heat and are present in the skin. They indicate temperature changes.
3. Photoreceptors: The photoreceptors are specific cells that respond to light. Rods and Cones are these types of receptors found in the retina of the eye.
4. Chemoreceptors: Chemoreceptors are sensory receptors that respond to chemical substances. Chemoreceptors contain olfactory receptors which are found in the nose and help in detecting smell.

Disorders of Sense Organs

1. Myopia or near-sightedness causes difficulties in seeing objects at a distance.
2. Hyperopia or far-sightedness causes difficulties in which nearby objects are blurry.
3. Cataracts create a clouding area over the front part of the eye.
4. Conjunctivitis causes inflammation of the conjunctiva.
5. Colour blindness happens due to the lack of one or more types of colour receptors.
6. Deafness is a partial or total hearing loss.
7. Sensory Processing Disorder is a condition in which sensory signals do not get processed into appropriate responses.
8. Sinusitis is a condition in which inflammation of the mucous membranes in the sinuses takes place.
9. Eczema is a condition in which white or scaly patches develop on the skin.
10. Acne is a condition in which blackheads, whiteheads, pimples, and painful cyst occurs on the skin.
11. Glossitis is a condition of soreness of the tongue.

Sense Organs Name: Summary

The human body is an amazing structure. We learn and understand the surrounding environment through our senses. The five sense organs of the human body are the eyes, ears, tongue, nose, and skin. Smell is considered to be the strongest sense. Additionally, the skin is the largest sense organ. Sense organs help us to respond to and collect information from the outside world and transmit the information to our central nervous system where the information processing is done.

FAQs on Sense Organs

The most frequently asked questions about sense organs are answered here:

Q.1: What are the 6 sense organs?
Ans: The six sense organs are-
a. Eyes
b. Ears
c. Nose
d. Tongue
e. Skin
f. Vestibular system

Q.2: What are sense organs?
Ans: The organs which enable a human body to perceive and respond to the surrounding environment. are known as sense organs.

Q.3: What are the 5 sense organs and their functions?
Ans: Humans have five sense organs.
The five sense organs are:
(a) Eyes- Helps to see
(b) Ears- Helps to hear
(c) Nose- Helps to smell
(d) Tongue- Helps to smell
(e) Skin- Helps to feel

Q.4: Name the photoreceptors of the eye.
Ans: The rods and cones are the photoreceptors of the eye.

Q.5: What is the Organ of Corti?
Ans: The Organ of Corti is an organ of the inner ear located within the cochlea which contributes to hearing.

Q.6: How many taste buds are present in the tongue?
Ans: On average, a person has about ten thousand taste buds.

Q.7: What is deafness?
Ans: Deafness is the condition that takes place when a person partially or completely loses the ability to hear.

Q.8: What are the five sense organs?
Ans: The five sense organs are the eye, ear, nose, tongue, and skin.

Q.9: Which is the strongest sense?
Ans: Smell is considered to be the strongest sense.

Q.10: What is the largest sense organ?
Ans: Skin is the largest sense organ.

You can also check,

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NEET Mock Tests  (Class 11-12 PCB)	NEET Practice Questions  (Class 11-12 PCB)

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We are blessed with various sense organs that work hand in hand with our brains to provide us with various types of sensory perceptions of our surroundings. When each sense organ works efficiently in our body we can see, hear, smell, taste and feel. They are a very special part of the human body and support us to recognise the outside world.

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