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Our retinas cannot detect the color red Our retinas cannot detect the color red!!!! 'Although your retinas have red, green and blue color receptors, the "red" receptor only detects yellow-green, and the "green" receptor detects blue-green. Your brain combines these signals and turns them into red. Isn’t incredible. Read on to learn more incredible facts about our senses.....

Learning Objectives

After completing the topic, the student will be able to:

  • Describe the basic function of sensory system and list the major types of senses in our body
  • Discuss the phenomenon of sensory adaptation with examples
  • Analyze how all the senses are alike and how they are different
  • Describe the function of sensory receptors and how they work.
  • Identify the different parts of eye and how vision works
  • Describe the phenomenon known as "Interpretation" and how rods and cones work for perfect vision
  • Analyze why “ear” is said to be a mechanical organ and identify the parts of ear
  • Determine how do we hear and how we determine variations in sound
  • Explore and understand the basic function of “vestibular apparatus” and how it balances the human body.
Brain Brain: A receptor and processor of senses 'Senses – sight, smell hearing, touch and taste – collect information about our environment that are interpreted by the brain.
Introduction

Do you believe that our perceptions of the world – its textures, colors, and sounds; its warmth, smells, and tastes – are created by the brain? Yes – It is the pathway from electrochemical nerve impulses delivered to brain from sensory receptors. These receptors transduce (change) different forms of energy in the "real world" into the energy of nerve impulses that are conducted into the central nervous system by sensory neurons. Different modalities (forms) of sensation – sound, light, pleasure, and so forth – result from differences in neural pathways and synaptic connections. The brain thus interprets impulses arriving from the auditory nerve as sound and from the optic nerve as sight, even though the impulses themselves are identical in the two nerves.

Thus, our senses help us perceive the world around us. In this chapter, we will explore the body's general senses. We will take a closer look at vision and hearing and examine the intricate structures of the eye and ear.

Senses work Senses are transducers from the physical world to the realm of the mind The sensory organs detect all types of changes in the environment and send appropriate signals to the central nervous system, where all the inputs are processed and analyzed.
Sense organs - How senses work?

A sensory system is a considered as a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory receptors to recognize the stimuli, neural pathways to carry that stimuli, and parts of the brain involved in sensory perception. Most commonly known sensory systems are those for vision, auditory (hearing), somatic (touch), gustatory (taste), olfaction (smell) and vestibular (balance/movement). Sensory reception occurs through a process known as signal transduction, in which stimuli are converted into nerve impulses and relayed to the brain. Putting simply, senses are transducers from the physical world to the realm of the mind where we interpret the information, creating our perception of the world around us.

The somatic cells present in the body respond to both external and internal stimuli. Due to these stimuli, we feel the climatic changes in the environment, we see an object and its color, and we hear a sound. Although most of the somatic receptors are located in the skin (conveying the external sensations of touch, heat, cold, pressure, and pain), others are located in internal organs (e.g.; the heart and the stomach). Somatic sensations such as hunger, thirst, and fatigue are thought to originate in specific areas of the nervous system. The sense of balance, or equilibrium, is related to the flow of endolymph, a fluid found in the inner ear.

Thus, the sensory organs detect all types of changes in the environment and send appropriate signals to the central nervous system, where all the inputs are processed and analyzed. Signals are then sent to different parts or centers of the brain. This is how we can sense changes in the environment.