Module 1
1. Module 1
1.25. Page 7
Module 1—The Nervous System
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?
You discovered 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. Temperature 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.
Lesson Glossary
Consult the glossary in the textbook for other definitions that you may need to complete your work.
chemoreceptor: a sensory receptor that transmits information about the solute concentration in a solution or about individual kinds of molecules in solution
mechanoreceptor: 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
olfactory epithelium: a patch of tissue located in the upper part of the nasal cavity that contains mucous-secreting cells and olfactory cells, or smell cells, that can detect different smells; a sense organ for smell
osmoreceptor: a sensory receptor that detects changes in osmotic pressure, pressure due to water movement
perception: the interpretation of sensory information by the cerebral cortex
photoreceptor: a sensory receptor that responds to light stimuli, allowing people to see images and 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 may be 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 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)
taste bud: a sensory organ composed of a taste pore, taste cells, and sensory fibres of a sensory neuron involved in initiating taste sensations
thermoreceptor: a sensory receptor that detects heat or cold