Question

When a sensory receptor receives a threshold stimulus, it will do all of the following EXCEPT A. become depolarized. B. transduce the stimulus to an action potential. C. inhibit the spread of the action potential to sensory neurons. D. cause the sensory neurons to send action potentials to the central nervous system.

Short answer

Option C is the exception.

Step-by-step solution

Understanding the Question

Identify what the sensory receptor does when it receives a threshold stimulus. We're looking for the exception, which means identifying the action it does NOT perform.

- Depolarization

A receptive sensory receptor, when stimulated, will become depolarized. This is a common feature in the process of initiating an action potential. Therefore, option A is something that does happen.

- Transduction

The receptor will transduce the stimulus into an action potential. Transduction converts the physical stimulus into an electrical signal. Therefore, option B is something that happens.

- Sensory Neurons

A threshold stimulus will cause sensory neurons to send action potentials to the central nervous system, facilitating the communication of sensory information. Therefore, option D is something that happens.

- Inhibition of Action Potential Spread

Upon receiving a threshold stimulus, a sensory receptor would not inhibit the spread of the action potential to the sensory neurons. This goes against how sensory receptors function. Therefore, option C is the exception.

Key concepts

threshold stimulus

Sensory receptors are specialized cells that detect environmental changes. When these receptors receive a stimulus, they need a certain minimum intensity to respond. This minimum intensity is called the 'threshold stimulus'. If the stimulus is not strong enough to reach this threshold, nothing happens. But if it surpasses the threshold, the sensory receptor gets activated.
The threshold stimulus ensures that the sensory receptors only respond to significant changes in the environment, avoiding constant triggering by minor fluctuations.

depolarization

Once a sensory receptor receives a threshold stimulus, it undergoes a process called depolarization. This is a change in the cell's electrical state. Normally, the inside of a cell is negatively charged compared to the outside. During depolarization, positive ions rush into the cell, making the inside more positive. This change in electrical charge is the first step in sending a signal down the nerve.
Depolarization is crucial because it starts the series of events that lead to nerve signal transmission.

transduction

The process of converting a physical stimulus like touch, light or sound into an electrical signal is called transduction. For instance, when touching a hot surface, the sensory receptors in your skin convert that heat into an electrical message. This message can then be processed by your nervous system.
Without transduction, our bodies wouldn't be able to interpret environmental stimuli. It's the bridge that connects the external world with our internal sensory experiences.

action potential

After transduction and depolarization, the final step is generating an action potential. An action potential is an electrical impulse that travels along the nerve. It is how sensory information gets from the receptor to your brain or spinal cord.
This electrical signal is like a message sent through the nervous system. It helps your body respond to different stimuli, such as pulling your hand away from a hot stove to avoid getting burned.
Action potentials are essential for communication within the nervous system, ensuring quick and efficient responses to changes in your environment.