Class 10 Reflex Arc and Nervous vs Hormonal Control
A response begins with information about a change and ends with an action. Naming the parts is useful only when you can explain the direction in which information travels.
Sources checked 2 October 2026 · original study guide · CBSE/NCERT context
Process guide · Read at your own pace
Trace a withdrawal reflex
Receptor
Detects the stimulus at the sensory ending.
Sensory neuron
Carries information towards the central nervous system.
Relay in the spinal cord
Connects the incoming information to a motor pathway in this simplified reflex.
Motor neuron
Carries the signal towards an effector.
Effector
A muscle contracts, producing withdrawal.
Do not remove the brain from the story
A withdrawal reflex can be coordinated through the spinal cord without waiting for a conscious decision. Information also reaches the brain. Saying “the brain is never involved in reflexes” is too broad; different reflexes have different coordinating centres.
The stimulus is the detected change, the nerve signal carries information, and the response is the resulting action. Calling all three “electricity” loses the biological meaning of the sequence.
Compare communication methods
Swipe across the table to see all columns.
| Feature | Nervous signalling | Hormonal signalling |
|---|---|---|
| Route | Neurons and synapses | Chemical messengers carried in body fluids |
| Target | Specific connected cells | Cells with the relevant receptors |
| Typical pattern | Rapid and often brief | Often slower and longer-lasting; varies by hormone |
Connect a plant response to its cause
A shoot bending towards light is a directional growth response. The school model connects unequal auxin distribution to unequal elongation on the two sides. Do not describe the shoot as deciding where to move or confuse growth with a muscle-driven movement.
To revise a coordination answer, underline each causal word: detects, transmits, stimulates, contracts or grows. Then check that the named structure can perform that action. A list of organs with no direction arrows is harder to use than a clear pathway.
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Sources and scope
This is a focused learning resource, not a complete chapter or a prediction of board questions. Use your current syllabus and the paper-specific marking scheme for assessment requirements.
Frequently asked questions
Are all involuntary actions reflex actions?
No. Involuntary describes lack of conscious control. Reflex refers to a particular automatic response pathway to a stimulus.
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