How do sensory receptors convert stimuli into electrical signals?

Sensory receptors convert stimuli into electrical signals through a process called transduction.

Transduction is the process by which sensory receptors convert physical or chemical stimuli into electrical signals that can be interpreted by the nervous system. This process is fundamental to how organisms perceive and interact with their environment.

Sensory receptors are specialised cells that can detect specific types of stimuli, such as light, sound, temperature, pressure, or chemical composition. These receptors are often located in sensory organs like the eyes, ears, skin, tongue, and nose. When a stimulus is detected, it triggers a change in the receptor's membrane potential. This change is called a receptor potential.

The receptor potential is an electrical signal that is generated by the movement of ions across the receptor's membrane. This movement is usually triggered by the opening or closing of ion channels, which are protein structures embedded in the membrane. The type of ion channel that is activated and the direction of ion movement will determine whether the receptor potential is a depolarisation (a decrease in membrane potential) or a hyperpolarisation (an increase in membrane potential).

If the receptor potential reaches a certain threshold, it will trigger an action potential. An action potential is a rapid, large change in membrane potential that travels along nerve fibres to the central nervous system. This is how the nervous system receives information about the stimulus.

The strength of the stimulus is encoded in the frequency of action potentials. A stronger stimulus will cause the sensory receptor to generate action potentials more frequently. This allows the nervous system to distinguish between different intensities of stimuli.

In summary, sensory receptors convert stimuli into electrical signals through the process of transduction. This involves the generation of a receptor potential, which may trigger an action potential if it reaches a certain threshold. The frequency of action potentials encodes the strength of the stimulus, allowing the nervous system to interpret the information.