Correct Sequence of a Simple Reflex:

The correct sequence of a simple reflex is as follows:
Receptor - Sensory Nerves - Central Nervous System (CNS) - Effector.

Explanation:

The simple reflex arc is the basic pathway through which a reflex action occurs. It involves a stimulus that is detected by a receptor, which then sends a signal through sensory nerves to the central nervous system (CNS), where it is processed. The CNS then sends a signal through motor nerves to an effector, which carries out the appropriate response.

1. Receptor:
The first step in a simple reflex arc is the detection of a stimulus by a receptor. Receptors are specialized structures, such as sensory neurons, that can detect changes in the external or internal environment. They are typically located in organs, tissues, or specialized cells, and they convert the stimulus into an electrical signal.

2. Sensory Nerves:
Once the receptor detects a stimulus, it sends an electrical signal through sensory nerves. These nerves are responsible for transmitting the signal from the receptor to the CNS. They are specialized for carrying information from the periphery of the body to the CNS.

3. Central Nervous System (CNS):
The sensory nerves carry the signal to the CNS, which consists of the brain and spinal cord. The CNS is responsible for processing and integrating the incoming sensory information. In the case of a simple reflex, the CNS quickly analyzes the signal and generates a motor response.

4. Effector:
After processing the sensory information, the CNS sends a signal through motor nerves to an effector. The effector is the structure or organ that carries out the appropriate response to the stimulus. It can be a muscle, gland, or any other tissue that can produce a response. The effector receives the signal from the motor nerves and executes the required action, such as contracting a muscle or secreting a hormone.

Importance of the Correct Sequence:
The correct sequence of a simple reflex is crucial for the proper functioning of the body. If the sequence is disrupted or the signals are not transmitted correctly, the reflex action may be delayed or impaired. This can lead to difficulties in responding to stimuli, which can have serious consequences for an individual's health and well-being.

Conclusion:
In summary, the correct sequence of a simple reflex is receptor - sensory nerves - CNS - effector. This sequence ensures that the stimulus is detected, transmitted to the CNS, processed, and then elicits an appropriate response from the effector. Understanding this sequence helps in understanding the basic functioning of reflexes and their importance in maintaining homeostasis and protecting the body.