1. Inhibitory neurotransmitters are released from the presynaptic neurone into the synaptic cleft
2. Inhibitory neurotransmitters bind to chloride ion (Cl^-) protein channels on the postsynaptic neurone
3. Cl^- protein channels open and Cl^- enters the postsynaptic neurone by facilitated diffusion
4. Potassium ion (K⁺) protein channels open in the postsynaptic neurone membrane and K⁺ exits the postsynaptic neurone
5. The membrane becomes hyperpolarised

A synapse is the point where one neurone communicates with another neurone or with an effector.

Synapses are important in linking different neurones together and therefore coordinating activities.

1. Synapses transmit information from one neurone to another, using chemicals called neurotransmitters
2. A single impulse can be used to initiate new impulses in several different neurones
3. Multiple impulses from different sources can be combined into a single response

1. Presynaptic neurone - neurone along which the impulse has arrived, which releases neurotransmitters into the synaptic cleft
2. Synaptic knob - swollen end of the presynaptic neurone, which contains mitochondria and endoplasmic reticulum for neurotransmitter production
3. Synaptic vesicles - vesicles within the synaptic knob that store neurotransmitters and release them into the synaptic cleft when an action potential reaches the knob
4. Synaptic cleft - gap between the presynaptic and postsynaptic neurone
5. Postsynaptic neurone - neurone that receives neurotransmitter and generates new nerve impulses
6. Neurotransmitter receptors - specific molecules on the postsynaptic membrane that bind to neurotransmitters, initiating a response in the postsynaptic neurone

Synapses are described as unidirectional as they can only pass information in one direction, from the presynaptic neurone to the postsynaptic neurone.

Summation is a process in synapses where low-frequency action potentials can trigger a new action potential in the postsynaptic neurone through the rapid build-up of neurotransmitter concentration.

1. Spatial summation - multiple presynaptic neurones release enough neurotransmitter together
2. Temporal summation - a single presynaptic neurone releases neurotransmitter multiple times in a short period of time

Excitatory synapses produce depolarisation in the postsynaptic neurone, leading to the triggering of an action potential if the threshold potential is reached.

Inhibitory synapses release neurotransmitters that hyperpolarise the postsynaptic membrane, preventing triggering of an new action potential in the postsynaptic neurone.