Our day-to-day survival depends on us reacting to various things happening in the outside world. For this to happen, the brain needs to process information gained from our environment. This is done through the sense organs.
A human being has five types of senses. These are:
- Sense of sound (Auditory sensations): Perceiving different vibrations around us. Is done through the ears.
- Sense of smell (Olfactory sensations): Perceiving the sense of smell. Is achieved through the nose.
- Sense of taste (Gustatory sensations): Perceiving the sense of taste. Is achieved through the tongue.
- Sense of vision (Visual sensations): Perceiving the different imagery around us. Is achieved through the eyes.
- Sense of touch (Somatosensory sensations): Perceiving the sense of touch. Is achieved through the skin.
Sense organs like the eyes and ears, as well as other sense organs like the nose, tongue, etc, make use of specialized cells for receiving information and turn them into electronic signals for transport to the brain.
The visual system
The visual system is responsible for the perception of light. It is sensitive to different kinds of light from different sources and translates this light into signals, which our brain interprets to form images.
The inside of our eyes has a certain spot known as the retina, which has thousands of special cells which are sensitive to light. Light enters our eyes through the pupil and passes through a lens that directs the light toward the retina. The retina transforms this light into signals, which are then sent to our brains to form images. Much like other sense organs, the eyes translate stimuli into electrical signals which are interpreted by the brain.
The Olfactory system
Different chemicals in the atmosphere stimulate the system to form signals, which our brain interprets as different smells. The auditory system consists of the nose and the special receptors inside it. The nose has two holes, which open up into two separate nasal cavities.
The Inside of our nose is lined with little nerve receptors at the end of microscopic hair-like structures called cilia. When the gas enters the nasal chamber, some molecules of the gas bind with the receptors, which then send signals to the nerves, and eventually to the brain. This system helps us to be aware of certain harmful chemicals and also subconsciously helps us in recognizing certain substances.
The Gustatory system
This system is useful for recognizing different substances that we put in our mouths for consumption. This helps in warning against harmful substances that might taste “unnatural” and maybe even food that has been spoiled.
Our tongue is covered with little bumps known as taste buds. These taste buds contain special cells called gustatory cells. When we put something on our tongue, the chemicals from it stimulate these taste buds, which are then translated into signals. These signals are transported to the brain by nerves, and the brain interprets these signals in the form of different tastes. Unlike other sense organs, the tongue consists of fairly simple parts and does not have a very complicated process in order to perceive taste.
The auditory system
The auditory system is characterized by the perception of vibrations or sound waves. It consists of two main parts- the inner ear and the outer ear. The outer ear captures sounds, whereas the inner ear processes sound for them to be sent to the brain.
The outer ear has an unusual funnel-like shape, which helps it to receive sound waves. These waves travel through the ear canal and hit a small diaphragm known as the eardrum. This eardrum vibrates, which in turn vibrates three small bones attached to each other- known as the auditory ossicles. These bones repeatedly hit the inner ear, which consists of canals filled with a type of fluid. These canals have special sensitive cells, which pick up the waves in the fluid formed due to the impact of the bones. This stimulates the nerves, and the brain interprets these vibrations as sounds that we hear. The ears work in tandem with the other sense organs to provide us with proper sensations.
The somatosensory system
The somatosensory system is responsible for giving us the sense of touch. This helps us make sense of tactile stimuli. Different aspects of an object like hardness, texture, and temperature can be determined by these stimuli. Our body achieves this through the skin.
The skin can be divided into three layers- the outer epidermis, the middle epidermis, and the inner hypodermis. The presence of different types of receptor cells within these layers facilitates the detection of stimuli. The type and position of these cells determine which parts are more sensitive than the other.
Conclusion
Sensory organs allow us to perceive the external world. The sensory nerve system receives impulses from sense organs in response to environmental inputs. They are specialised organs that assist us in perceiving our surroundings. These sense organs are a crucial aspect of the human body because they allow us to experience reality. The traditional five senses — sight, hearing, touch, taste, and smell – are well-known, but recent research suggests that there are numerous more. Understanding the five primary sense organs is beneficial in our daily life.