Sensation: Receiving messages about the world Sense organs operate through sensory receptor cells that receive external forms of energy and translate these external forms into neural impulses that can be transmitted to the brain There are two types of sense organs which we will examine in this chapter
Sensation: Receiving messages about the world • Sense organs operate through sensory receptor cells that receive external forms of energy and translate these external forms into neural impulses that can be transmitted to the brain • There are two types of sense organs which we will examine in this chapter
Basic function Sequence of Events in a Receptor Stimulus Reception Receptor protein Activated Amplification Enzyme Cascade (in some cases) Receptor lon Channels opened (or closed) Receptor Current Transduction Receptor potential Modulated transmitter Release from receptor cell Modulated Impulse Transmission Modulated Impulse Frequency in Second Frequency in Receptor Order Neuron Cell Axon
Sequence of Events in a Receptor Stimulus Receptor Protein Activated Enzyme Cascade (in some cases) Receptor Ion Channels opened (or closed) Receptor Current Receptor Potential Modulated Impulse Frequency in Second Order Neuron Basic Function Reception Amplification Transduction Transmission Modulated Impulse Frequency in Receptor Cell Axon Modulated Transmitter Release from Receptor Cell
II Properties of the receptors
II Properties of the Receptors
1. Adequate Stimulus of Sensory Receptors
1. Adequate Stimulus of Sensory Receptors
Each type of receptor is highly sensitive to one type of stimulus for which it is designed and yet is almost nonresponsive to normal intensities of other type of stimul The stimulus to which a given receptor has the lowest threshold is termed the adequate stimulus of the sensory receptor For instance, the roes and cones are highly responsive to light but almost completely nonresponsive to heat and cold
Each type of receptor is highly sensitive to one type of stimulus for which it is designed and yet is almost nonresponsive to normal intensities of other type of stimuli. The stimulus to which a given receptor has the lowest threshold is termed the adequate stimulus of the sensory receptor. For instance, the roes and cones are highly responsive to light but almost completely nonresponsive to heat and cold