Define reflex action. Explain different components of reflex arc.
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Answer:
Reflex action is a nerve mediated rapid, spontaneous, autonomic and involuntary response. First of all Marshal Hall discovered this phenomenon in 1833. CNS is connected with reflex action due to which it can be spinal reflex or cerebral reflex. Reflexes are classified into two types depending upon their development, one is unconditioned and conditioned reflexes.
A stimulus for an unconditioned response is known as the unconditioned stimulus.
When reflex actions are not present at the time of birth but develop later in life through experience, habit, learning etc. These reflexes are called conditioned reflex or acquired reflexes.
Reflex arc: Reflex arc is a pathway taken by the nerve impulse that generated at the receptor due to the stimulus to reach the effector organ at the time of reflex action.
Components of reflex arc: There are components of reflex arc as follow:
1. Receptors: A cell or tissue that receive a stimulus such as skin, eye, ear etc.
2. Afferent nerve fibres: Receive sensory nerve impulse by the receptor to the CNS.
3. Part of CNS: It can be ganglion or spinal cord or brain. Sensory nerve impulse transferred from CNS to the motor nerve fibres.
4. Efferent nerve fibres: They carry the nerve impulses that are generated in CNS to the effectors.
5. Effector organ: It can be gland or muscle or organ which produce work on activation.