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.
What are the three neurons?
1- Motor neuron
2- Sensory neuron
3- Relay neuron
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
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
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
What is the structure of a neuron?
2- Cell body
4- Myelin sheath
What is a dendrite?
- Carry nerve impulses from close neurons to the cell body
What is the cell body?
- Includes a nucleus which contains genetic material of the cell
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
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.