Grade 3 Sense Organs | Human Body | Learning Concepts
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Human Body

Concept: Sense Organs

  • There are various kinds of changes happening in our surroundings.
  • We observe, feel or sense the differences in the surrounding by particular organs called the sense organs.
  • These organs collect information about the changes and passes to the brain. The brain works on these pieces of information and orders the body to act accordingly.

Our senses and the related sense organs:

We have five different senses—vision, hearing, smell, taste and touch, and the sense organs related to these are the eyes, ears, nose, tongue and skin.

1. Eye:

  • The eyes are the sense organs for vision. The pair of eyes notice the changes in the light in the surrounding.
  • The different parts of the human eye are shown in the following image—
  • Nature-1
  • The sensory cells in the eyes are called photoreceptors.
    There are two types of photoreceptors—rod cells and cone cells.
Photoreceptors
Rod cells Cone cells
Responsible for the vision in low light. Responsible for colour vision in bright light.
There are about 120 million rod cells in the eye. There are about 6-7 million cone cells in the eye.

2. Ear:

  • Humans can hear different sounds because of a pair of ears.
  • Hearing is possible due to the sound passing through the ear that is divided into the external ear, middle ear and inner ear.
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  • The external ear helps collect different sounds and pass them to the middle part of the ear.
  • The middle ear contains a delicate part called the eardrum that vibrates after receiving the sound.
  • These vibrations are picked up by the inner ear that sends the stimulus to the brain.

3. Nose:

  • Humans can smell by their noses.
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  • The air that enters the nose brings different odours that touch the smell receptors.
  • Our brain helps to understand and identify different smells after receiving the stimulus from the smell receptors in the nose.

4. Tongue

  • We get to know about the tastes of food by our tongue.
  • The tongue understands and identifies different tastes due to tiny receptors all over the tongue.
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  • The back of the tongue is more sensitive to the bitter taste to avoid swallowing rotten/spoiled food.
  • The basic tastes that our tongue understands are sweet, sour, salty, bitter and savoury. The savoury taste is also called ‘umami’.

5. Skin:

  • The skin is the largest sense organ that covers all the other organs and protects us from external injuries.
  • It consists of different layers of tissues that help sense many stimuli.
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    Nature-1
  • Our skin can detect pain, itchiness, touch, vibration, heat, cold, pressure, etc.

Diseases related to sense organs:

Sense organ Diseases
Eyes Farsightedness, Near-sightedness, Conjunctivitis
Ears Ear squeeze, inflammation of inner parts, deafness
Nose Sinusitis
Tongue Swelling and infections
Skin Acne, Psoriasis

Care of sense organs:

One should care about their sense organs to avoid any related diseases and ensure the proper functioning of the body.

Sense organ How to take care
Eyes Eat a healthy diet with green vegetables, fruits, milk, etc. Avoid watching mobile/TV/computer for a long time.
Ears Never use pointed things to clean the ears. Avoid listening to loud music.
Nose Never poke the nose by any pointed things. Clean the nose regularly while taking a bath
Tongue Clean the tongue using a tongue cleaner and wash your mouth properly after eating the meals.
Skin Bath regularly using good soap and consult the doctor if there are any rashes on the skin.

New Words:

Stimulus: Any kind of change in the surrounding that causes a sudden change in the body after sensing.

Did You Know?

  • The inner ear is also responsible to convey the brain about the change in the posture or position of our body.
  • Taste (from the tongue) and smell (from the nose) receptors give the perception of food flavour.
  • There is no taste as ‘spicy’! The ‘spicy’ or ‘hot’ is a state of pain perceived by the taste buds to the brain.
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