Sense Organs

Overview

Description

Sensory receptors detect information about the internal and external environment of the body. These receptors are classified by three different characteristics: structure, location, and stimulus type. When classified by structure, receptors can belong to either the general senses or special senses. Structural receptors gather information through neurons with free nerve endings or neurons with encapsulated endings. Receptors are located throughout the body, such as tactile receptors in fingers, taste receptors on the tongue, or light receptors in the eyes. Receptors are also classified by their reactions to stimuli, specifically chemical stimuli (chemoreceptors), mechanical stimuli (mechanoreceptors), potentially dangerous stimuli (nociceptor), or temperature (thermoreceptor). Receptors for the general senses are modified dendritic endings of sensory neurons. Receptors for the special senses are found within complex organs of the head. General senses detect information about pressure, pain, and temperature. Special senses include vision, hearing, equilibrium, smell, and taste.

At A Glance

  • Sensory receptors are responsible for receiving information from the internal and external environments and relaying the information to the central nervous system.
  • Sensory receptors are classified by their structure, location, and the type of stimulus received.
  • Sensory receptors respond to stimuli using specialized membrane proteins and relay information to the brain about the modality, location, intensity, and duration of the stimulus.
  • Specialized structures relay information to the brain about the modality, location, intensity, and duration of the stimulus.
  • General senses have simple receptors, which are distributed throughout the body to detect internal and external environmental conditions.
  • The eye is a complex sense organ with many external and internal structures that protect the eye or aid in vision.
  • Vision is one of the special senses that allows the body to detect light and relay messages to the brain to perceive images.
  • The ear is a special sense organ that receives sound stimuli and information about the orientation of the head, which influences equilibrium.
  • Hearing is the ability to receive and interpret sound waves.
  • Equilibrium is the detection of changes in position or movements of the head.
  • Olfaction, or smell, is the detection of airborne molecules using specialized receptors in the nasal cavity.
  • Gustation, or taste, is an important sense that depends on specialized receptors to detect favorable and unfavorable molecules in food that either harm or benefit the body.