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Three steps are common to all sensory reception:
1) a physical stimulus
2) a series of events that transduce the stimulus into a nerve impulse
3) a response to the message resulting in perception or inner representation of the sensation.
We receive sensory information from the external world
and from within the body. Information from the external world is received through
specialized cells at the periphery of the body and then transmitted to the CNS.
This information is used for 4 main functions: perception, control of movement,
regulation of internal organs and maintenance of arousal.
Information from within the body usually not conscious , information from
blood vessels, the muscles and joints and is used to regulate temperature, blood
pressure, heart rate, respiration rate and reflex movement.
1.CHEMORECEPTORS
2. MECHANORECEPTORS
3. PHOTORECEPTORS
4. THERMORECPTORS
5. NOCICEPTORS
(SEE TABLE 36.1)
1)SENSORY PATHWAY (see 36.2 and fig. 1)
RECEPTORS, PATHWAY TO CNS, SPECIFIC AREA OF THE BRAIN
PROCESSES THE INFORMATION
Sensory receptors : transduce energy in the environment into a nerve signal. As a rule stimulus acts on the membrane receptors.
Receptor detect, and amplify a signal, This results in a receptor potential.
Which can then generate action potentials
2) INFORMATION IS ENCODED IN THE FREQUENCY OF ACTION POTENTIALS
3) SENSORY SYSTEMS ALSO ADAPT; STIMULUS DURATION IS ENCODED IN ADAPTING RECEPTORS
