Why is response time in a monosynaptic reflex much faster than polysynaptic reflex?

Monosynaptic reflex involves the transmission of a nerve impulse from a sensory neuron directly to a motor neuron, without involving any interneurons. This allows for a very fast response time, as the signal does not have to pass through multiple synapses. The reflex arc is composed only of two neurons: a sensory neuron and a motor neuron.

Polysynaptic reflex, on the other hand, involves the transmission of a nerve impulse through one or more interneurons before reaching the motor neuron. This results in a longer response time, as the signal has to pass through multiple synapses, each of which introduces a slight delay. The reflex arc of a polysynaptic reflex consists of three or more neurons: a sensory neuron, one or more interneurons, and a motor neuron.

The response time of a reflex is important for its effectiveness in protecting the body from harm. For example, the knee jerk reflex, which is a monosynaptic reflex, helps to prevent the knee from buckling when it is suddenly loaded with weight. The faster response time of the monosynaptic reflex allows for a more rapid and effective response to the stimulus, which is crucial in preventing injury.