Chapter 46 - Chapter 46 Animal Sensory Systems and Movement...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 46: Animal Sensory Systems and Movement Key Concepts Sensory receptor cells transduce sound, light, or other stimuli to a change in membrane potential. Receptor cells or sensory neurons send action potentials to the brain, where the signals are processed and integrated. Hearing is based on sensory receptor cells that move in response to sound waves of a particular frequency. The movement opens ion channels in the sensory cells and results in a change in membrane potential. Vision is based on sensory receptor cells that contain a light-absorbing pigment bound to a protein. The pigment changes conformation when it absorbs light and triggers a series of events that changes the cell's membrane potential. Taste and smell sensations are registered by membrane proteins that act as receptors for particular molecules and that trigger changes in membrane potential. In many cases, animals respond to sensory stimuli by moving. Movement is based on antagonistic muscle groups that act on a stiff skeleton containing joints that flex or extend in response to electrical signals. Section 46.1 Outline: How Do Sensory Organs Convey Information to the Brain? Sensory Transduction Transmitting Information to the Brain The ability to sense a change in the environment depends on four processes: 1. transduction , the conversion of an external stimulus to an internal signal in the form of an action potential 2. amplification of the signal 3. transmission of the signal to the central nervous system (CNS) 4. integration , or processing with other signals. Transduction requires a sensory receptor cell to convert light, sound, tension, or some other stimulus into an electrical signal. Sensory receptors are located throughout the body and are categorized by the type of stimulus. Nociceceptors sense harmful stimuli. Thermoreceptors detect changes in temperature. Mechanoreceptors respond to distortion caused by touch or pressure.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Chemoreceptors perceive specific molecules or classes of molecules. Photoreceptors respond to particular wavelengths of light. Electroreceptors detect electrical fields. Sensory Transduction o Sensory input changes the membrane potential of receptor cells (Figure 46.2). o This change in potential allows different types of stimuli to be transduced into a common type of signal. o If ion flows cause the interior of the cell to become more positively charged (less negatively charged), the membrane is said to be depolarized . o If changes in ion channels cause the cell interior to become more negative than the resting potential, the membrane is said to be hyperpolarized . o The amount of depolarization of the sensory receptor is proportional to the intensity of the stimulus. Transmitting Information to the Brain
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/14/2010 for the course CHEM 23454 taught by Professor Screwu during the Spring '10 term at Shoreline.

Page1 / 10

Chapter 46 - Chapter 46 Animal Sensory Systems and Movement...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online