Chapter 15, Problem 1LO

Summary Introduction

To explain: The sensory receptors and its classification based on location and stimuli.

Concept introduction: The psychological capacity of an organism that provides a data for the perception is called the sense. The sense organs contain receptors that transmit information through sensory neurons to the corresponding organs in the nervous system.

Explanation of Solution

The sensory receptors are the structure that reacts to the physical stimulus in the environment. It has a sensory nerve ending that transmits the information through the process of generating nerve impulses to the brain for the perception and interpretation. Sensory receptors can be classified based on their location and stimuli.

Classification based on location:

Sensory receptors can be classified based on their location are given as follows:

• Exteroceptors
• Visceroceptors
• Proprioceptors

Exteroceptors: These receptors are also called cutaneous receptors. They are located on the body surface such as dermis and epidermis that receives the external stimuli. There are two kinds of exteroceptors and that are given as follows:

• Tactile receptors- Touch
• Cutaneous receptors- Pressure, light, and temperature.

Some of the special exteroceptors located in the head that are represented by the receptors for taste, smell, hearing, and vision.

Visceroceptors: These receptors are also called the internal receptors. These are the receptors that respond to stimulus in the visceral region that includes visceral organs and blood vessels. These receptors located inside the body surface. It provides information about the environment around the stimulus. It includes the receptors for blood pressure, blood pH, and blood volume.

Proprioceptors: These receptors are also called muscle sense. They provide information about the movement of the body, orientation, muscle stretch and its physical locations. They respond to the stimuli that occur in the skeletal muscles, ligaments, joints, and tendons.

Classification based on stimuli:

Sensory receptors are classified as six types based on their stimuli are given as follows:

• Mechanoreceptors
• Chemoreceptors
• Thermoreceptors
• Photoreceptors
• Nociceptors
• Osmoreceptors

Mechanoreceptors: These receptors respond to mechanical stimulus. For example: pressure, touch, equilibrium, and hearing.

Chemoreceptors: These receptors respond to dissolved chemicals during sensations of taste and smell. This also causes responses to the changes in the internal body chemicals such as difference in concentrations of oxygen, carbon dioxide, and hydrogen ions in the blood.

Thermoreceptors: These receptors respond to the change in temperature. They can be warm and cold receptors. These receptors are located on the skin and hypothalamus.

Photoreceptors: They are stimulated by light receptors. These receptors are present in the cells of retina.

Nociceptors: These receptors respond to various stimulus that are associated with tissue damage or intense mechanical stimuli. These stimuli are associated with pain that is interpreted by brain.

Osmoreceptors: These are specialized receptors that are located in the hypothalamus. It recognizes the changes in the osmotic pressure of fluids in the body.