What is meant by reflex-action? With the help of a labelled diagram trace the sequence of the event which occurs when we touch a hot object

What is meant by reflex-action? With the help of a labelled diagram trace the sequence of the event which occurs when we touch a hot object.

Hint: The word “reflex” is commonly used when we talk about sudden action or response to something in the environment, like the withdrawal of a body part from a hot or dangerous object.

Complete step-by-step answer:

A reflex action is a sudden and involuntary response of the body to a stimulus. It does not involve the conscious part of the brain. Reflex actions are quick and protect us from harm.

When we touch a hot object, the receptors in our skin detect the high temperature and send a signal through sensory neurons (afferent neurons) to the spinal cord. In the spinal cord, the signal is passed to a relay neuron (interneuron), which quickly sends it to a motor neuron (efferent neuron). The motor neuron then carries the signal to the muscles in the arm, causing them to contract and pull the hand away.

This pathway of nerve signals is known as the reflex arc.

Labelled Diagram (Textual Representation):

Stimulus (Hot object) → Receptor (Skin) → Sensory Neuron → Spinal Cord (Relay Neuron) 
→ Motor Neuron → Effector (Muscle) → Response (Hand pulled away)

Note:

• All impulses are received by the dendrites of the sensory neurons.
• Impulses travel through the axon to the synaptic terminal.
• The signal is transferred to the next interneuron via neurotransmitters like acetylcholine.
• Interneurons are also known as relay neurons.