Module 1 The Nervous System

1.1.4 page 7

Lesson Summary

In this lesson you investigated this focusing question:

• What information about the environment do the senses of touch, smell, and taste communicate to a person’s nervous system in order to maintain homeostasis?

 In this lesson you investigated how the body is able to gather information about the external and internal environment in order to maintain a constant internal environment, or homeostasis. The senses are the functional categories that scientists use to classify how the body gathers information. You studied the specialized neurons that respond to stimuli (types of energy). These specialized nerve cells are identified as

• mechanoreceptors

• chemoreceptors

• thermoreceptors

• photoreceptors 

The sensory receptors for taste and smell are chemoreceptors, while touch receptors are mechanoreceptors.  Hot and cold sensory receptors are thermoreceptors. The sensory receptors are able to initiate a nerve impulse that is transmitted through a sensory neuron to a specific part of the brain that is able to interpret the information. The brain initiates a response that maintains or returns the body to homeostasis. In Lesson 4 you learned how taste, smell, and touch reception occurs and how a nerve impulse is initiated so that the information can be transmitted to the brain for interpretation.

 

Lesson Glossary

chemoreceptors: a sensory receptor that transmits information about the solute concentration in a solution or about individual kinds of molecules in solution

 

mechanoreceptors: a sensory receptor that detects physical deformations in the body’s environment associated with pressure, touch, stretch, motion, and sound

 

olfactory (receptor) cell: a neuron located in the olfactory epithelium that is specialized to receive chemical stimuli and to initiate a nerve impulse

 

perception: the interpretation of sensory information by the cerebral cortex

 

photoreceptors: sensory receptors that respond to light stimuli, allowing people to see images as well as colours

 

sensation: the reception and processing by the brain of a nerve impulse sent by an activated sensory receptor

 

senses: specialized mechanisms or functions by which an organism is receptive and responsive to a certain class of stimuli which are typically external as in the senses of sight, hearing, touch, and pain but also internal as in sensing the temperature of the blood, or the levels of carbon dioxide

 

sensory adaptation: the tendency of sensory neurons to become less sensitive when they are repeatedly stimulated

 

sensory receptor: a cell or a group of cells located in various parts of the body that is specialized to receive stimuli that provide information about the body’s external conditions (through sight, hearing, taste, smell, or touch) and internal conditions (such as temperature, pH, glucose levels, and blood pressure)

 

tactile reception: the receiving of stimuli involving touch, pressure, vibration, and stretch

 

taste bud: a sensory organ composed of a taste pore, taste cells, and sensory fibres of a sensory neuron involved in initiating taste sensations

 

thermoreceptors: a sensory receptor that detects heat or cold