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Control and Coordination - Voluntary, involuntary and reflex action

Grade 10CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Voluntary Actions: These are actions performed consciously and are under the control of the will. They are coordinated by the ForebrainForebrain (specifically the CerebrumCerebrum). Examples include writing, dancing, and speaking.

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Involuntary Actions: These are automatic actions that occur without conscious thought and are not under our control. They are regulated by the MidbrainMidbrain and HindbrainHindbrain (specifically the MedullaMedulla). Examples include heartbeat, digestion, and PeristalsisPeristalsis.

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Reflex Action: A sudden, rapid, and automatic response to a stimulus that happens without conscious thought to protect the body from harm. These are mostly mediated by the Spinal CordSpinal\ Cord.

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Reflex Arc: The neural pathway that controls a reflex action. It involves a sequence: Receptor→Sensory Neuron→Spinal Cord→Motor Neuron→EffectorReceptor \rightarrow Sensory\ Neuron \rightarrow Spinal\ Cord \rightarrow Motor\ Neuron \rightarrow Effector.

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Synapse: The functional junction or gap between two neurons where the nerve impulse is transmitted via chemicals called NeurotransmittersNeurotransmitters.

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Effector: Usually a muscle or a gland that responds to the motor command received from the Central Nervous System (CNS)Central\ Nervous\ System\ (CNS).

📐Formulae

Stimulus→ReceptorSensory Neuron→IntegrationSpinal Cord→Motor NeuronEffector→ResponseActionStimulus \xrightarrow{Receptor} Sensory\ Neuron \xrightarrow{Integration} Spinal\ Cord \xrightarrow{Motor\ Neuron} Effector \xrightarrow{Response} Action

TimeReflex<TimeVoluntaryTime_{Reflex} < Time_{Voluntary}

Sensory Input+Spinal Processing=Rapid Motor OutputSensory\ Input + Spinal\ Processing = Rapid\ Motor\ Output

💡Examples

Problem 1:

Trace the path of a reflex arc when a person accidentally touches a hot object.

Solution:

Heat (Stimulus)→Thermoreceptors in skin→Sensory Neuron→Spinal Cord (Relay Neuron)→Motor Neuron→Bicep Muscle (Effector)→Hand withdrawn (Response)Heat\ (Stimulus) \rightarrow Thermoreceptors\ in\ skin \rightarrow Sensory\ Neuron \rightarrow Spinal\ Cord\ (Relay\ Neuron) \rightarrow Motor\ Neuron \rightarrow Bicep\ Muscle\ (Effector) \rightarrow Hand\ withdrawn\ (Response)

Explanation:

The stimulus is heat, detected by receptors in the skin. The signal travels via the sensory neuron to the spinal cord. The spinal cord processes it immediately and sends a command through the motor neuron to the muscles to contract, resulting in the withdrawal of the hand. This bypasses the brain for a faster response.

Problem 2:

Differentiate between the control centers of 'Walking' and 'Heartbeat'.

Solution:

Walking: Forebrain (Cerebrum)Forebrain\ (Cerebrum); Heartbeat: Hindbrain (Medulla Oblongata)Hindbrain\ (Medulla\ Oblongata)

Explanation:

Walking is a voluntary action requiring conscious decision-making and balance, hence controlled by the CerebrumCerebrum. Heartbeat is an involuntary vital function that must continue automatically, hence controlled by the MedullaMedulla in the hindbrain.

Voluntary, involuntary and reflex action Revision - Class 10 Science CBSE