Synaptic transmission Flashcards
what is is a synaptic transmission
a fundamental process by which neurons communicate with each other and other cells example being muscle cells.
why is neuron communication important
it is the primary source to everything physical and mental, emotional regulation to muscle movement is conducted through synaptic transmissions
step 1- action potential what is it
an electrical signal that is transmitted across the axon of a neutron it is the fundamental mechanism for communication within the nervous system
Resting potential?
at rest neurons have a net negative charge inside the cell in relativity to the outside, maintained through a sodium-potassium pump which actively transports 3 Na+ out of the cell and 2 K+ in.
depolarisation at the postsynaptic membrane, what happens, what does it do?
A neurotransmitter that has binded to a receptor on the postsynaptic membrane which causes a slight depolarisation inside of the cell. If a threshold value is reached, voltage-gated sodium channels open causing an influx of sodium ions to rush into the cell which consequently causes a rapid depolarisation. inside of the cell becomes positively charged
key characteristics of action potentials
Follow an all or none principle- it must occur fully, there can be no partial action potentials. threshold must be met
when the action potential reaches axon terminal…
it triggers openings of voltage-gated calcium channels at the presynaptic membrane
calcium ion influx causes what
the increased amount of calcium ions triggers the fusion of synaptic vesicles (membrane-bound structures that contain neurotransmitters) with the presynaptic membrane.
what proteins mediate process
A group of proteins known as SNARE complex mediate the fusion of vesicles to the presynaptic membrane, they facilitate the docking and fusion and lead to exocytosis
what is exocytosis
process by which neurotransmitters are released into the synaptic cleft
what occurs across the synaptic cleft and what are the types of receptors?
neurotransmitters will diffuse across the cleft and will bind to specific receptors on the postsynaptic membrane
ionotropic receptors
metabotropic receptors
postsynaptic potential?
the binding at receptors opens ion channels in the membrane leading to a change in the potential- postsynaptic potential
inotropic receptors- excitatory postsynaptic potential, opens channels and allows sodium ions to enter postsynaptic neuron
metabotropic- inhibitory postsynaptic potential opens potassium channels, hyperpolarisation make it less likely to fire an action potential
what are the 3 ways signals are terminated
reuptake by presynaptic neuron with the help of transporter proteins
enzymatic degradation- enzymes in cleft break down the neurotransmitters
diffusion away from the synapse
importance of synaptic transmission
sensory perception- transmitting signals from sensory receptors to brain
motor control
emotional regulation- modulating mood and behaviour
disruptions in synaptic transmission
epilepsy- excessive excitatory synaptic transmission
Parkinson’s disease- deficiency of dopamine- involved in motor control
schizophrenia- abnormalities in dopamine and glutamate signalling
depression- imbalances in serotonin, norepinephrine and dopamine
