Question

How do the following processes occur? We move our hands away from a hot object.

Answer 1

Reflexes are actions that take place without any conscious thought. These are very beneficial in getting organisms away from dangerous or harmful situations. These are rapid involuntary actions.

Complete answer:
In our bodies, we have neural pathways known as reflex arcs. These are simple nerve pathways between receptors that encounter a stimulus, and effector end organs that carry out the required action.
When we touch or are close to a hot object, temperature receptors in our skins are activated by the heat. They stimulate the sensory neurons which take this signal to the spinal cord.

Here the impulse is taken to the dorsal root ganglion of the spinal cord at that level and transmitted across a chemical synapse to an intermediate neuron. The intermediate neuron transmits the signal to the motor neuron in the ventral root. This motor neuron then takes the signal down towards the muscles of our hands and arms causing us to pull our fingers away. The sensory neuron is also called the afferent neuron as it brings the signal into the central nervous system, while the motor neuron is the different neuron, taking the signal away from the CNS.
The dorsal root ganglion will also send a message down another spinal neuron to the brain where this entire stimulus and response will then be consciously analysed and memorised.

Note: The advantage of reflex arcs is the speed in which the helpful response is carried out. If we were to wait for the signal to be routed via the brain before it reaches the effector organ, it is likely to be too late, resulting in greater harm.