sci_bio
Nervous System
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
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Biology · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
It is split into the CNS (brain and spinal cord) and the PNS (all other nerves). It detects stimuli and coordinates rapid responses.
A myelin sheath insulates the axon and speeds the impulse up. There are three types: sensory (in), relay (process), motor (out).
The pathway is receptor → sensory neuron → relay neuron → motor neuron → effector. It runs through the spinal cord, bypassing the brain, so it is fast.
The impulse releases neurotransmitter from vesicles; it diffuses across and binds receptors on the next neuron, triggering a new impulse. Many drugs act here.
Hard words & meanings
| neuron | a specialised nerve cell that transmits electrical impulses; has a cell body, dendrites and an axon |
| CNS | the central nervous system: the brain and spinal cord, where information is processed |
| PNS | the peripheral nervous system: all the nerves connecting the CNS to the rest of the body |
| synapse | the tiny gap between two neurons, crossed by chemical neurotransmitters |
| neurotransmitter | a chemical released at a synapse that carries the signal to the next neuron |
| reflex arc | the nerve pathway of a reflex: receptor, sensory, relay, motor neuron, effector |
| effector | a muscle or gland that carries out the response to a stimulus |
| myelin sheath | a fatty insulating layer around an axon that speeds up impulse conduction |
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