Neurons as cells within the nervous system that carry electrical impulses
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Question
What is a neuron?
Answer
A **nerve cell** — the cell specialised to carry **electrical impulses** around the body.
Question
In what order does a nerve impulse travel through a neuron?
Answer
**Dendrites → cell body → axon → axon terminals** (always one direction).
Question
What is the job of the dendrites?
Answer
They **receive incoming signals** and carry them towards the cell body.
Question
What does the axon do?
Answer
It carries the **nerve impulse away from the cell body** towards the axon terminals.
Question
What does the myelin sheath do?
Answer
It is a **fatty layer** that **insulates the axon** and **speeds up** the nerve impulse.
Question
What are the nodes of Ranvier?
Answer
The **gaps between segments of the myelin sheath**, where the impulse 'jumps' so it travels faster.
Question
What is the function of a sensory neuron?
Answer
It carries impulses **from receptors TOWARDS the CNS** (it brings information in from the senses).
Question
What is the function of a motor neuron?
Answer
It carries impulses **from the CNS TO effectors** (muscles and glands), producing a response.
Question
What is the simplest way to tell sensory and motor neurons apart?
Answer
By **direction**: sensory carry impulses **TO** the CNS, motor carry impulses **FROM** the CNS.
Question
What is an effector?
Answer
A **muscle or gland** that carries out a response (by contracting or by releasing a secretion).
Question
What are the two components of the central nervous system (CNS)?
Answer
The **brain** and the **spinal cord**.
Question
What is the peripheral nervous system (PNS)?
Answer
**All the nerves outside the brain and spinal cord**, connecting the CNS to the rest of the body.
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