the sensory systems collect signals in the environment and convey them to the CNS
sound: change of air pressure
- action potential can upkeep an amplitude for a long distance because it can regenerate itself due to the Na+ channels
- amplitudes don’t differ in the same neuron, but can differ across neurons
- action potential doesn’t carry info, it is the timing (the signal is digital)
- change in the environment provide signals (light, chemical, mechanical)
Mechanical = Touch and Hearing (hearing is the movement of physical objects, no physical contact)
Chemical = Olfaction and Taste
- conversion happens in 3 steps
1. electrical signals of the environment converted into receptor potential
2. needs to be sensed by a receptor, becomes converted into electrical signal in the receptor = membrane potential = receptor potential (if it happens in the receptor)
- receptor potential is incremental and is reflecting the signal in the outside
3. receptor potential converted to action potential along the afferent fiber (action potential is digital = can propagate long distance w/out changing amplitude
What is in common?
- parallel processing in multiple pathways, work in parallel, in any given time, all of them are telling something to the brain, true for all sensory systems
- two steps processing
- the difference is the receptor, convert external signals into incremental change
(axon terminal = receptor potential at a receptor, variation among type of sensory system)
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