REFLEX ACTION -

• Marshel Hall discovered reflex action. Best & Taylor defined it. Reflex action is functional unit of CNS.
• It is sudden, immediate involuntary action against external stimuli. In man it is poly-synaptic.
• If we prick needle on skin, somatic sensory nerves bring impulses to grey matter. Here these are analysed & order is given to muscle by motor nerve.
• The path from which impulse is passed is reflex arch.
• Minimum time is consumed in it. It is not under control of brain.

Some common reflex actions are -

1. Coughing

2. Yawning

3. Sneezing

4. Knee-jerk reflex

5. Bleenking of eyes

6. Scratch reflex

EXAMPLE -

1.       Cycling.

2.       Watering of mouth.

3.       Blinking of eyes in sharp light.

4.       Withdrawal of leg in pithed frog.

5.       Flow of bile from gall bladder.

6.       Peristalasis.

7.       Heart beat.

SIGNIFICANCE -

1. It enables animal to respond immediately to the harmful stimuli so that no harm is caused to it.

2. It gives more time to brain to work.