Nervous System (Animals) MCQs Quiz | Class 10

Nervous System in Animals: A Detailed Overview

The nervous system is an intricate network of cells and tissues that enables animals to perceive their environment, process information, and respond accordingly. It acts as the body’s control and communication center, coordinating voluntary and involuntary actions.

I. Structure Overview

The nervous system can be broadly divided into two main parts:

1. Central Nervous System (CNS):
   • Brain: The command center, responsible for thought, emotion, memory, and coordinating most body activities.
   • Spinal Cord: A long, tubular structure extending from the brainstem, transmitting nerve signals between the brain and the rest of the body. It also mediates reflex actions.
2. Peripheral Nervous System (PNS):
   • Comprises all the nerves that branch out from the brain and spinal cord to other parts of the body, including muscles and organs.
   • It acts as a communication relay between the CNS and the rest of the body.

II. The Neuron: The Basic Unit

The fundamental structural and functional unit of the nervous system is the neuron, or nerve cell. These specialized cells transmit electrical and chemical signals throughout the body.

A typical neuron consists of three main parts:

1. Dendrites: These are short, branched extensions that receive nerve impulses (signals) from other neurons and transmit them towards the cell body. Think of them as the “receivers.”
2. Cell Body (Soma): This central part contains the nucleus and other organelles. It processes the incoming signals and generates an outgoing signal if the stimulus is strong enough.
3. Axon: A long, slender projection that extends from the cell body and transmits nerve impulses away from the cell body to other neurons, muscles, or glands. Axons can be very long, sometimes over a meter.

Additional Neuron Structures:

• Myelin Sheath: Many axons are covered by a fatty layer called the myelin sheath, which insulates the axon and significantly increases the speed of nerve impulse transmission.
• Synapse: The small gap at the end of a neuron that allows a signal to pass from one neuron to another. When an electrical impulse reaches the end of an axon, it triggers the release of chemical messengers called neurotransmitters into the synapse, which then bind to receptors on the next neuron’s dendrite.

How a Nerve Impulse Travels: Nerve impulses are electrochemical signals. They start at the dendrites, move through the cell body, down the axon, and then transmit across the synapse to the next neuron.

III. Functions of the Nervous System

• Sensory Input: Detecting changes (stimuli) inside and outside the body (e.g., light, sound, touch, temperature).
• Integration: Interpreting and processing sensory input, making decisions.
• Motor Output: Responding to stimuli by activating muscles or glands.
• Reflex Actions: Involuntary, rapid responses to stimuli that bypass conscious thought (e.g., withdrawing hand from a hot object). The pathway involved is called a reflex arc.

Quick Revision Checklist

• Nervous System: Controls and coordinates body functions.
• CNS: Brain and Spinal Cord.
• PNS: Nerves extending from CNS to the rest of the body.
• Neuron: Basic unit of the nervous system.
• Dendrites: Receive signals.
• Cell Body: Processes signals.
• Axon: Transmits signals away.
• Myelin Sheath: Insulates axon, speeds up impulse.
• Synapse: Gap between neurons where signals are transmitted chemically.
• Neurotransmitters: Chemical messengers at synapses.

Practice Questions

Test your understanding further with these questions:

1. What is the primary role of the central nervous system?
2. Describe the function of dendrites in a neuron.
3. How does the myelin sheath contribute to nerve impulse transmission?
4. Explain the concept of a synapse and its importance.
5. Name the two main divisions of the nervous system and their primary components.