What is meant by reflex action? Explain the formation of reflex arc by means of schematic diagram.

Explanation

### Step-by-Step Solution:

1. **Definition of Reflex Action**:
Reflex action is defined as a quick and automatic response to a stimulus. It occurs without conscious thought and is an immediate reaction to a specific stimulus. For example, when exposed to bright light, the pupil of the eye constricts to protect the retina from excessive light.

2. **Characteristics of Reflex Action**:
- **Quick Response**: Reflex actions are rapid and occur almost instantaneously after the stimulus is detected.
- **Involuntary**: These actions do not require conscious thought or decision-making, as they are controlled by the nervous system.
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