Lesson 3- Process of Synaptic Transmission- Neurotransmitters, Excitation & Inhibition Flashcards
What is synaptic transmission?
Synaptic transmission- process by which ⚡️ nerve impulses are transmitted (action potential) across synaptic cleft between 1 neuron (pre-synaptic) and the next neuron (post-synaptic)- nerve impulses carried by chemicals 🧪 called neurotransmitters
What is action potential?
Action potential- electrical impulses that neurons transmit- created when neurons send info along axon away from cell body
- pre synaptic neuron transfers action potential
- post synaptic neuron receives action potential
Describe the process of synaptic transmission (how messages are transmitted from one neuron to the next)
1) When the action potential (⚡️ impulse) reaches pre-synaptic terminal- triggers release of neurotransmitters (chemical messengers) from sacs on pre- synaptic membrane (in the synaptic knob) known as vesicles in process called exocytosis
2) The released neurotransmitters diffuse in synaptic fluid across synaptic cleft (physical gap between pre-synaptic and post-synaptic membrane)
3) Neurotransmitters received by dendrites of post-synaptic neuron and bind to specialised post-synaptic receptor sites via 🔒 and 🔑 mechanism
4) This then creates⚡️ impulses to send along axon
5) Effects of synaptic transmission terminated by process called re-uptake (neurotransmitters taken back by vesicles on pre-synaptic neuron (in pre-synaptic knob)- stored for later release)
In how many directions can information travel at a synapse?
ONLY in 1 direction
Why can information only travel in one direction at a synapse?
1) Vesicles containing neurotransmitters ONLY present in pre-synaptic knob of the pre-synaptic membrane
2) Receptors for neurotransmitters ONLY present on post- synaptic membrane
3) Diffusion of neurotransmitters means they only go from high to low concentration … only travel from pre-synaptic to post-synaptic membrane
- Binding of neurotransmitter to receptor enables info to be transmitted to next neuron … info can ONLY travel in 1 direction
What are psychoactive drugs?
Psychoactive drugs- medication that affects 🧠 function to alter perception, mood or 🏃♂️ e.g. SSRIs
How do psychoactive drugs work?
Work by affecting (increasing ⬆️ or inhibiting ⬇️) transmission of neurotransmitters across synapse
What are the 2 types of neurotransmitters?
1) Excitatory
2) Inhibitory
What do excitatory neurotransmitters do?
Cause an ⚡️ charge in membrane of post-synaptic neuron-> an excitatory post-synaptic potential (means that post-synaptic neuron ⬆️ likely to fire 🔥 impulse)
What do inhibitory neurotransmitters do?
Cause an inhibitory post-synaptic potential (means that ⬇️ likely that post-synaptic neuron fires 🔥 impulse)
What types of neurotransmitters can a neuron receive?
A neuron can receive both excitatory post-synaptic potential causing neurotransmitters and inhibitory post-synaptic potential causing neurotransmitters at the same time
What determines whether a neuron fires 🔥 or not?
- Likelihood that cell 🔥s impulse determined by adding up excitatory and inhibitory synaptic input
- Net result of calculation (summation)- determines whether or not cell 🔥s impulse
- If net effect is inhibitory- then neuron ✖️ fire BUT if net effect excitatory- then neuron 🔥s
