Structure and function of neurons


What are neurons?

They are part of the nervous system. 80% are located in the brain. They transmit signals electronically and chemically. Neurons are a way of communicating with the nervous system.

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What are the three neurons?

1- Motor neuron

2- Sensory neuron

3- Relay neuron

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What is a motor neuron?

- Connects CNS to effectors such as muscles and glands

- Has short dendrites and long axons

- Carries information from the brain to the body

- A motor neuron is a nerve cell located in the spinal cord

- The axon protects the spinal cord to directly or indirectly control effector organs

- The motor neuron axons carry signals from the spinal cord

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What is a sensory neuron?

- Carry messages from PNS to CNS

- Have long dendrites and short axons

- Sensory neurons transmit sensory info like sight, sound and feeling

- They are activated by sensory input and send prohections to other parts of the nervous system, showing sensory info to the brain

- Not all of these travel to the brain

- Some terminate in the spinal cord to allow reflex actions to happen quickly without the delay of sending nerve impulses to the brain

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What is a relay neuron?

- Found in the brain and spinal cord

- Connect sensory neurons to motor or other relay neurons

-  Has short dendrites and short axons

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What is the structure of a neuron?

1- Dendrites

2- Cell body

3- Axon

4- Myelin sheath

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What is a dendrite?

- Carry nerve impulses from close neurons to the cell body

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What is the cell body?

- Includes a nucleus which contains genetic material of the cell

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What is myelin sheath?

- It has gaps call nodes of ranvier. These speed up transmission by forcing it to jump acorss the gaps along the axon

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What is an axon?

- Covered in myelin sheath which protects the axon and speeds up electrical transmission of the impulse. Axon carries impulses away down the length of the neuron.

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