Which action is a reflex action? A. asking for coffee in a cold climate B. blinking when light is flashed in the eyes C. drinking water when thirsty D. swallowing food E. taking an exam
Answers
A reflex Action
This is an involuntary and nearly instantaneous movement in response to a stimulus.
From the choices above the action best defined by this is :
B. Blinking when light is flashed in the eye.
This action is involuntary and instantaneous.
The stimulus here is light.
Correct answer: B). Blinking when light is flashed in the eyes
A reflex action is the body's involuntary response to the external stimuli, which protect the body from the immediate harm.
Normally when a receptor is stimulated, it transfer the signal to the central nervous system (CNS) and then response is generated by the brain. But, sometime a very quick response is needed, which does not need involvement of brain. It is quick and rapid process and occur without thinking.
In vertebrates, sensory neurons do not pass directly through the brain, but synapse in the spinal cord, which allow the reflex action to take place by activating motor neuron without causing delay in the passage of signal through then brain.
Example: Sneezing when an unwanted or foreign particle enters the nose. Blinking of the eyes when foreign particles get in to them.