Topic 3 (chemical synapses) Flashcards
what mv causes the voltage gated calcium channels to open?
voltage gated calcium channels open when the membrane depolarises to -60 to -40 mv
is the calcium influx in the presynaptic termial down or against the concentration and electrical gradients?
calcium flows in down the concentration and electrical gradient
how does the neurotransmitter release vescicles?
Vescicles have v-SNARE proteins and the membrane has t-SNARE proteins
Each snare protein has a lipophilic section inside the membrane and a hydrophilic section outside the membrane
When calcium binds to these protein it allows them to link together and enable the vescicle to dock on, the membranes to fuse and the vescicle contents to be released into the extracellular space
what is an axospinous synapse?
a small presynaptic axon terminal contacts a postsynaptic dendritic spine
What is an axosomatic synapse?
- axons contact the postsynaptic syanpse
What is the synapse in the Calyx of Held?
- the unusually large axon terminal surrounds the post synaptic soma
- this allows a quick transmission of action potentials
- it is found when the auditory sensory neurons connect to neurons in the pons
what is translocation of neurotransmitters
when vescicles move in and out of the synaptic bouton
what role do astrocytes play in synapses
clear up neurotransmitters
how do astrocytes clear up excess glutamate?
they ustilise excitatory amino acid transporters (EAAT’S)
glutamate transporters in the astrocyte hoover up all of the glutamater
This is then converted to glutamine and sent back to the neurons
What are 7 excitatory neurotransmitters?
Glutamate Acetylcholine Histamine Dopamine Norepinephrine Noradrenaline
What are 3 inhibitory neurotransmitters
GABA
serotonin
dopamine
What are 3 glutamate receptors and what are they permeable to?
AMPA- Na+ and K+
Kainate- Na+ K+ and Ca2+
Nmda- Na+ K+ and Ca2+
What are GABAa receptors permeable to?
Cl-
What ions are excitatory and inhibitory receptors permeable to?
Excitatory:
k+ leaves the cell and Na+ / Ca2+ enters
Inhibitory:
Cl- enters
what are the two types of EPSP summation
temporal and spatial