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Control and Coordination - Nervous system

Grade 10CBSE

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

🔑Concepts

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The nervous system is the system of neurons, nerves, and ganglia that coordinate the activities of the animal body and transmit signals between different body parts.

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The neuron is the structural and functional unit of the nervous system, consisting of the cell body (cyton), dendrites, and an axon. Electrical impulses travel from the dendrite to the axon terminal.

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Synapse is the microscopic gap between two neurons where the electrical signal is converted into a chemical signal using neurotransmitters to cross the gap.

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Reflex Action is an intermediate, involuntary response to a stimulus. The pathway followed is the Reflex Arc: Receptor→Sensory Neuron→Spinal Cord→Motor Neuron→EffectorReceptor \rightarrow Sensory \, Neuron \rightarrow Spinal \, Cord \rightarrow Motor \, Neuron \rightarrow Effector.

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The Human Brain is divided into three main parts: Forebrain (Cerebrum for thinking and memory), Midbrain (controls certain involuntary actions), and Hindbrain (Cerebellum for posture/balance, Medulla for blood pressure/vomiting, and Pons for respiration).

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The Central Nervous System (CNS) consists of the Brain and Spinal Cord, while the Peripheral Nervous System (PNS) consists of Cranial and Spinal nerves.

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Information in neurons travels via electrochemical gradients involving ions like Na+Na^+ and K+K^+.

📐Formulae

Stimulus→Receptor→Sensory Neuron→Spinal Cord→Motor Neuron→Effector→ResponseStimulus \rightarrow Receptor \rightarrow Sensory \, Neuron \rightarrow Spinal \, Cord \rightarrow Motor \, Neuron \rightarrow Effector \rightarrow Response

Electrical Impulse (Dendrite)→AxonChemical Signal (Synapse)→Electrical Impulse (Next Neuron)Electrical \, Impulse \, (Dendrite) \xrightarrow{Axon} Chemical \, Signal \, (Synapse) \rightarrow Electrical \, Impulse \, (Next \, Neuron)

💡Examples

Problem 1:

What is the sequence of events when a person touches a hot object accidentally?

Solution:

The stimulus (heat) is detected by thermo-receptors in the skin. The Sensory NeuronSensory \, Neuron carries the impulse to the spinal cord. In the spinal cord, the signal is transferred to a Motor NeuronMotor \, Neuron via a relay neuron. The motor neuron carries the signal to the effector (muscles of the hand), causing the hand to withdraw.

Explanation:

This is a reflex action designed to protect the body from damage. The brain is informed later, but the immediate response is handled by the spinal cord to save time.

Problem 2:

Differentiate between the functions of the Cerebrum and the Cerebellum.

Solution:

The Cerebrum is part of the forebrain and is responsible for Intelligence, Memory, and Voluntary actionsIntelligence, \, Memory, \, and \, Voluntary \, actions. The Cerebellum is part of the hindbrain and is responsible for Precision of voluntary actions and maintaining the posture and balance of the bodyPrecision \, of \, voluntary \, actions \, and \, maintaining \, the \, posture \, and \, balance \, of \, the \, body.

Explanation:

While both involve movement, the cerebrum decides to walk (voluntary), but the cerebellum ensures you walk in a straight line (coordination).