2.89 understand the role of neurotransmitters at synapses

*To fully understand this syllabus point, some background information needs to be understood. Therefore I have put up some important things you need to fully grasp in order to move on to this topic below. If you know all of this already, scroll down to where I go into the details of this syllabus point
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Neurones: specialised cells in the nervous system, adapted to send nerve impulses.
There are 3 types of Neurones, classified to their functions:

1. Sensory Neurones: afferent neurones, take nerve impulses from receptors to CNS.
2. Relay Neurones: found within CNS, link sensory neurones to motor neurones.
3. Motor Neurones: efferent neurones, take nerve impulses from the CNS to muscle or gland.

This is a motor neuron. It is a motor neurone since the cell body is at one end of the cell. Structures that carry a nerve impulse towards the cell body are called dendrites. The axon is the long thin projection of the cell that takes the nerve impulse away from the cell body. 

*Neurones can only send electrical impulses in one direction.





This is a sensory neuron. This can be easily identified as a sensory neuron it has receptors at one end collecting sensory information to take to the CNS. Cell body perpendicular to the axon/dendron.

Motor and sensory neurones are usually surrounded by myelin sheath.
Myelin is a type of lipid that acts as an insulator, acting as a catalyst that speeds up the electrical impulse.
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Synapse: gap between 2 neurons, where transmission of impulse is chemical rather than electrical. Nerve cells are linked together by synapses.
Neurotransmitter: chemical substance released at the end

Detailed process:

1. electrical impulse is carried along an axon and triggers the nerve ending of a neuron to release neurotransmitters
2. neurotransmitters will diffuse across synapse and bind with receptor molecules on the membrane of the second neuron.
3. receptor molecules on second neuron bind only to specific neurotransmitters released from the first neuron
4. this stimulates the second neuron to transmit an electrical response.