III Sensory Hair Cell Transduction Mechanisms that underlie Hearing and Equilibrium.
Sensory Nervous System Objectives: Describe the process of sensory transduction in general List...
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Transcript of Sensory Nervous System Objectives: Describe the process of sensory transduction in general List...
Sensory Nervous System Objectives:
Describe the process of sensory transduction in general
List the stimuli to which we have receptors and, for each, identify the general type of receptor
Distinguish receptor potential from action potential
Distinguish tonic and phasic receptor function
Somatic sensesfine touch, deep touch, pressure, temp, pain,
joint and muscle position, muscle stretch
Visceral senses pH, O2, CO2, OsM, glucose, blood pressure, lunginflation, stomach stretch
Special sensesolfaction, gustation, hearing, equilibrium, vision
ear (sense organ)with mechanoreceptors(transducers)
CNS (decoder)-medulla to thalamus toauditory cortex
Vestibulocochlear nerve
non-neural receptors-receptor potentials(like graded potentials)
graded potentials
action potentials
coding: which receptors are activated and AP frequency
Receptors are transducers, neural or non-neuralTypes: chemo-, mechano-, photo-, thermo-, noci-
General principles of sensory function
1. Each sensory organ and receptor is specialized to convert one form of stimulus into sensory neuron action potentials.
2. Each modality has a discrete pathway to the brain.
3. The specific sensation and location of stimulus perceived is determined by area of brain activated.
4. ‘Intensity’ is coded by frequency of action potentials and number of receptors activated.
Group the following senses according to whether they use chemical or mechanical receptors.
taste (gustation) pain (nociception)smell (olfaction)touch
vibrationvisionoxygen levelspressure (baroreception)
Which one can be both and which one is neither?
-chem-chem and mech-chem-mech-mech-neither-chem-mech
A somatic sense: touch• Free nerve endings• Meissner’s corpuscle (light)• Pacinian corpuscles (deep)
Example sensory pathway: touch
(receptor cell) sensory neuron to spinal cord or brainstem to thalamus to somatosensory cortex
General principles of sensory function
1. Each sensory organ and receptor is specialized to convert one form of stimulus into sensory neuron action potentials.
2. Each modality has a discrete pathway to the brain.
3. The specific sensation and location of stimulus perceived is determined by area of brain activated.
4. ‘Intensity’ is coded by frequency of action potentials and number of receptors activated.
The specific sensation and location of stimulus perceived
is determined by area of brain activated.
FREQUENCY CODINGLIGHT PRESSURE
LOW FREQUENCY
MORE PRESSURE
HIGHERFREQUENCY
‘Intensity’ is coded by frequency of action potentials and number of receptors activated.
POPULATION CODING
LIGHT PRESSURE
MORE PRESSURE
‘Intensity’ is coded by frequency of action potentials and number of receptors activated.
Receptor Types
Chemoreceptors : pH, O2, CO2, glucose, taste, odor, some pain
Mechanoreceptors : muscle, cell, joint, lung, blood vessel and stomach stretch, sound, equilibrium
Photoreceptors : lightThermoreceptors : hot or cold
All receptors are transducers sensitive to a specific stimulus. Some are neurons, some are not.
General principles of sensory function Somatic senses -touch, pressure, temp, pain
Objectives: For each sense identify…
• Any specialized structures or sense organs
• Receptor type
• Receptor signal transduction mechanism
• Coding of intensity and duration
• Pathway of conduction to the CNS
• Coding for perceived sensation