Sensory Organs

The sense organs are the body organs by which humans are able to see, smell, hear, taste, and touch or feel. The five sense organs are the eyes (for seeing), nose (for smelling), ears (for hearing), tongue (for tasting), and skin (for touching or feeling).

See the fact file below for more information on the sense organs.

Key Facts & Information

The Five Senses

• Senses are important because they allow us to perceive the world in which we live.
• Our five senses are our sense of sight (also known as vision), smell (olfaction), hearing (audition), taste (gustation), and touch (somatosensation).
• A sense is our ability to detect stimuli which are then interpreted and responded to accordingly.
• Humans are not the only creatures with sensory capacity – animals have senses too.
• The degrees of sensory capability vary among species. Some animals have a weaker sense of smell than others. Some have a sharper sense of sight, etc.
• Sensory organs are organs of the body that access those sensory capabilities and help us become conscious and respond to our surroundings.
• There are two types of receptors depending on the sensory organ: general receptors and special receptors.
• General receptors are present in the skin and muscles.
• Special receptors are in the form of photoreceptors (in the eyes), chemoreceptors (in the mouth and nose), and mechanoreceptors (in the ears).

Eyes

• Sight, also referred to as vision, is our ability to see.
• Eyes are the visual sensory organs of the human body.
• Other animals, birds, and fish also see through their eyes.
• Human eyes vary in color depending on the amount of melanin in the body.
• Eye colors can be brown, blue, gray, green, and even combinations.
• Our eyes are sensitive to images of light.
• Seeing occurs when eyes detect and focus on these images.
• The scientific study of sight is called optics.
• Photoreceptors present in the eye’s retina are what translates light into images.
• Rods and cones are the two types of photoreceptors.
• Rods are more sensitive to light and motion while cones are more sensitive to colors and details.
• The optic nerve is what carries the impulses to the brain.
• Blindness is the inability to see.
• Blindness can be temporary or permanent.
• Causes of blindness include, but are not limited to, injury to the eyeball, damage to the optic nerve, and trauma to the brain.

Ears

• Hearing, also referred to as auditory perception or audition, is our ability to perceive sounds.
• We have our auditory system by which we detect vibrations and hear sounds.
• Our ears are auditory organs.
• Vibrations are transmitted through a medium such as air.
• These vibrations are mechanically carried on from the eardrum through the tiny bones named the malleus, incus, and stapes.
• Mechanoreceptors in the inner ear turn vibrations into electrical nerve pulses.
• An impulse is then sent through the cochlea to the eighth cranial nerve then to the brain.
• Humans may experience hearing loss when the ability to hear is lost partially or completely.
• Deafness is the inability to hear.

Nose

• The sense of smell is also referred to as olfaction.
• We have our olfactory system by which we smell and perceive different odors and scents.
• The nose is an olfactory organ.
• The nose can also be an organ to aid in our sense of taste.
• Humans breathe through two holes called nostrils.
• There are hundreds of olfactory receptors that interpret the smells around us.
• When you smell a substance, the chemicals present bind to the cilia in your nasal cavity.
• Afterwards, it produces a nerve impulse which is transported through the olfactory cell, then to the olfactory nerve fiber, then to the olfactory bulb and ultimately, to the brain.
• Olfactory receptor neurons in the nose have the unique ability to regularly die and regenerate.
• Olfactory neurons in the nose can also detect pheromones, which is a chemical substance released by humans which could affect how they relate with each other.
• Animals generally have a sharper sense of smell than humans.
• Anosmia is the inability to smell.

Tongue

• We have one tongue by which we perceive various tastes and flavors like sweet, salty, sour, and bitter.
• The small bumps on the tongue are the papillae.
• In between the papillae are the taste buds.
• Taste buds, also called gustatory calyculi, are the sensory organs on the tongue’s upper surface.
• The different parts of the tongue detect distinct flavors: front for salty and sweet, back for bitter, and sides for sour.
• The fifth basic taste is called umami.
• Taste, also referred to as gustation, is the sense we use to detect the taste of food and other substances.
• Ageusia is the inability to taste.

Skin

• Our skin is the largest organ as it covers our whole body.
• The receptors on our skin allow us to perceive texture, pain, temperature, pressure, and pain.
• Touch is also referred to as tactician, somatosensation, or mechanoreception.
• The sense of touch is activated by neural receptors found in the skin, and other surfaces like the tongue and hair follicles.
• Skin receptors generate an impulse which is carried to the spinal cord then to the brain.
• Pressure receptors in the skin are sensitive to changes in pressure.
• Itch-specific neurons in the skin give us the touch sense of itching.
• Tactile anesthesia is the inability to feel anything physically.