RECEPTOR PHYSIOLOGY SUMMARY NOTES, SUMMARY NOTES ON Cholesterol Metabolism, Summarized Notes on Development of the hindgut

RECEPTOR PHYSIOLOGY

• Definition of receptor

• Types of receptors

• Adaptations in receptors

• Properties of receptors

• Receptor potential

DEFINITION




• Receptors are trasducers , they convert stimuli into electrical
impulse.




• Sensory receptors are specialized epithelial cells or neurons
that transduce environmental signals in to neuronal signals.


FUNCTIONS OF RECEPTORS
1. Transduction
2. Amplification
3. Transmission
4. Integration

, SENSORY RECEPTORS
1. Sensory Transduction
• Conversion of stimulus energy into membrane potential •
of receptor cell
• Begins by a change in membrane permeability
• results in “graded” change in membrane potential



“RECEPTOR POTENTIAL”


• Is graded: proportional to strength of stimulus can be
due to change in ion permeability :
1. as gated ion channels respond to receptor
molecule
(a ligand binds to)
2. or due to actual stretching of membrane in
response to pressure.



SENSORY RCEPTORS


2. AMPLIFICATION - strengthening of a stimulus too
weak to be carried into nervous system • Direct -
Complex organ, ear: sound waves

• magnified 20X

, • Part of transduction in eye: 100,000X of action
potential in signal to brain from eye, vs. few
photons of light energy trigger process

SENSORY RECEPTORS


3. TRANSMISSION - conducting impulses to CNS

• Some cases, pain receptor, is a sensory neuron that
conducts signal
• other receptors transmit chemical signals (neurotransmitters)
across a synapse to a sensory neuron

• •Stimulus does not turn on/off production of action potential
but controls the frequency with which they are
generated…

• can detect a change in stimulus intensity,

• not just presence or abscence of stimuli.



SENSORY RECEPTORS



• 4. Integration - processing of information > begins
immediately integration via summation of graded
potentials.