Sense Organs

What are sense organs? The only window to this world around us is our senses or in other words, we use senses to perceive the world around us. They include sight, sound, speech, taste and last but never the least, touch. These 5 senses govern our association with this world around us. It is important to comprehend the eminence of the fact that, right here, of the five senses is the root of all understanding. All knowledge stems from what we perceive through the five senses guide our understanding of all that surrounds us. Therefore, the significance of this is never trivial.

The human senses contain receptors that relay information through sensory neurons to the appropriate places within the nervous system. The receptors could be classified into two parts viz. the general and special receptors. The former is present throughout the body while the latter includes chemo receptors, photoreceptors, and mechanoreceptors. The five senses are:

Sense Organs

Sense Organs

 

  1. Sight or ophthalmoception: The iris in the eye is the colored part that controls the size of the eye. Behind the lens of the eye, one would find the vitreous body, which is filled with a gelatinous material called the vitreous humor. This substance gives shape to the eyeball and also transmits light to the very back of the eyeball, where the retina lies.  This retina contains photoreceptors, which detect light.Two types of sensors detect light viz rods which detect motion work harder in low light and cones which detect fine detail and color, work best in bright light. There are three types of cones like the one that detects blue, the one that detects red and the one that detects green. Color blindness occurs when one type of cone is not present.
  2. Hearing or audioception: It is not only responsible for hearing but also for maintaining balance or equilibrium. For this, the ear must detect motion, hence they respond to mechanical stimulation by sound waves. The eardrum sets the mechanics in motion. The brain then interprets them.
  3. Taste or Gustaoception: The senses, smell, and taste tend to work closely together. The key sense organ would be the tongue. If one could not smell something, they could not taste it either.Taste buds on the tongue contain chemo receptors that work similar to the chemo receptors in the nasal cavity. But, the chemo receptors in the nose would detect any kind of smell, whereas there are four different types of taste buds and each one detect different types of tastes like sweet, sour, bitter, and salty.
  4. Smell or olfalcoception: The olfactory cells tend to line the top of your nasal cavity.On one end, olfactory cells have cilia that project into the nasal cavity and on the other end of the cell, are the olfactory nerve fibers. As one breathes, anything that is in the air enters your nasal cavity. The olfactory cells are the chemoreceptors, which goes to mean that the olfactory cells have protein receptors that could detect subtle differences in chemicals. The chemicals bind to the cilia, which generate a nerve impulse that is carried to your brain. Your brain then determines what we had smelled.
  5. Touch or tactioception: The skin contains general receptors which could detect touch, pain, pressure, and temperature. They are present throughout the skin. Skin receptors generate an impulse once activated is carried to the spinal cord and then to the brain.

Practise This Question

The posterior pituitary gland is not a 'true' endocrine gland because