Lesson 3 - Synaptic Transmission Flashcards
What is synaptic transmission?
Synaptic transmission is the process by which action potentials are transmitted across the synaptic cleft between neurons
What carries action potentials between neurons?
Neurotransmitters
Describe the process of synaptic transmission:
When the action potential reaches the pre-synaptic terminal, neurotransmitters are released which are located in sacs called vesicles in a process called exocytosis. The neurotransmitters diffuse across the synaptic cleft where it then proceeds to bind to post-synaptic receptor sites.
What is re-uptake and how does it work?
Re-uptakes terminates the effects of synaptic transmission.
This is achieved by the vesicles on the pre-synaptic neuron taking back the neurotransmitters so that they can be stored for later release. The faster the neurotransmitter is taken back by the vesicles, the shorter the effects off synaptic transmission are).
How many directions can action potentials travel across the synaptic cleft?
Action potentials can only travel in ONE direction as vesicles with neurotransmitters in them are ONLY present on the PRE-synaptic membrane and receptor sites that the neurotransmitters bind to are ONLY present on the POST-synaptic cleft.
In what ways do psychoactive drugs associate with synaptic transmission? What is an example?
Psychoactive drugs work by either increasing or inhibiting the transmission of neurotransmitters across the synapse.
SSRI’s (Selective Serotonin Re-Uptake Inhibitors) work by inhibiting the re-uptake of serotonin (a neurotransmitter which regulates our mood) after synaptic transmission so that serotonin is present in our body for a longer period of time which eases depressive symptoms by making people happy for longer.
What are the two types of neurotransmitters?
Excitatory
Inhibitory
Most neurotransmitters can be BOTH but GABA is mainly inhibitory.
What are Excitatory neurotransmitters?
When EXCITATORY neurotransmitters bind to the membrane of the post-synaptic neuron during synaptic transmission, a POSITIVE electrical charge is caused resulting in an EXCITATORY POST-SYNAPTIC POTENTIAL (EPsP). This means that the post-synaptic cell is MORE likely to ‘FIRE’ the electrical impulse onto its neighbouring neuron and activate it.
What are Inhibitory neurotransmitters?
When INHIBITORY neurotransmitters bind to the membrane of the post-synaptic neuron during synaptic transmission, a NEGATIVE electrical charge is caused resulting in an INHIBITORY POST-SYNAPTIC POTENTIAL (IPsP). This means that the post-synaptic neuron is LESS likely to ‘FIRE’ the electrical impulse onto its neighbouring neuron.
What is summation?
Summation is a net calculation which determines whether the post-synaptic cell will fire an electrical impulse or not.
A neuron can recieve both excitatory and inhibitory post-synaptic potentials at the same time. The likelihood that the post-synaptic cell will fire an electrical impulse is determined by adding up the excitatory and inhibitory neurotransmitters - the net results of this calculation is known as summation.
