neurones and synaptic transmission Flashcards
What is synaptic transmission?
Synaptic transmission is a method of neurons communicating with each other, relaying information to the CNS across sensory neurons and carrying out responses dictated by the brain through sending information to effectors via motor neurons.
What happens when an action potential arrives at the presynaptic membrane?
An action potential causes depolarisation through the opening of voltage-dependent calcium ion channels, leading to an influx of calcium ions.
What is the role of calcium ions in synaptic transmission?
Increased concentration of calcium ions causes vesicles containing neurotransmitter to fuse with the presynaptic membrane and release their contents into the synaptic cleft through exocytosis.
What occurs after neurotransmitter release into the synaptic cleft?
The neurotransmitter diffuses across the synaptic cleft, binds to complementary receptors on the post-synaptic membrane, and can result in an inhibitory or excitatory effect.
What is the result of neurotransmitter binding on the postsynaptic membrane?
The resultant action potential will then be transmitted along the axon of the following neuron, resulting in a ‘cascade’ of neurotransmission!
What effect do inhibitory neurotransmitters have?
Inhibitory neurotransmitters (e.g. serotonin) reduce the potential difference across the postsynaptic membrane, decreasing the likelihood of action potential generation.
What effect do excitatory neurotransmitters have?
Excitatory neurotransmitters (e.g. dopamine) increase the potential difference across the postsynaptic membrane, increasing the likelihood of action potential generation.
