VPB 121: Veterinary Physiology - II (2+1)

MECHANISM OF ACTION OF A RECEPTOR

• Incoming stimuli transduce the membrane potential into the receptor or generator potential.
• The protein structures within the sensory receptors absorb energy from stimuli to undergo conformational change which in turn activate signal transduction pathway.
• This allows change with appropriate voltage gated channel to induce the impulse generation through the proper neurotransmitters.
• Sensory reception include signal reception, signal transduction, signal amplification, signal transmission to higher centres and perception at the integrating centre.

Properties of Sensory Reception

• Primary afferent neuron is the cell whose axon carries the information to higher centres.
• Sensory receptor cells are present in the sense organs.

Generator potential vs Receptor potential

• If the potential developed by sensory receptor which also serve as primary afferent neuron, is termed as Generator Potential.
• If sensory receptor cell is different from primary afferent neuron the potential developed in the sensory receptor cell is termed as Receptor Potential.
• Mechanism of signal transduction varies in each of these situations.

Receptor characteristics

• Receptors have the ability to convert other form of energy in to electrical energy i.e. action potential, causes transduction if adequate stimuli is applied.
• They have differential sensitivities to different stimuli. The permeability of the receptor is modified and ends up in graded receptor potential.
• They show different adaptability to a stimulus and speed of adaption varies with receptors. Each receptor has specific acuity i.e. discriminative ability.