Presynaptic terminals Flashcards
What was the reticular theory [2]
-nervous system made of a continuous mesh of nerve processes
-without microscopy gap could not be seen
How did Golgi aid Cajal’s discovery [3]
-Golgi discovered silver salts could be used to stain neurones
-meant canal could see gaps between neurones
-confirmed nervous system is contiguous/made of individual cells
Describe Sherringtons discoveries [5]
-times how long it took for signal to travel from sensory to motor neurones
-time was more than conduction speed
-therefore there must delays
-delays due to gaps
-gaps=synapses
What is the length of a synapse
~20nm
What is the length of synaptic vesicles
~40nm
Describe how vesicles are filled with neurotransmitters [3]
-ATPase pumps protons into vesicle
-creates proton gradient
-vesicular transporters pump transmitter in exchange for proton (coupling)
Explain how action potentials lead to the release of neurotransmitters [4]
-influx of Na+ in action potential
-causes Ca+ (P/Q and N type) channels to open
- Calcium binds to proteins on vesicles
-conformation change
-releases neurotransmitters
Describe how a vesicle releases neurotransmitters
-SNARE proteins mediate binding of vesicle to pre-synaptic membrane
-vesicle temporarily becomes part of the membrane
-covered by Cathrin
-neurotransmitters released
-vesicle then retunes inside (endocytosis)
What is the AIS (axon initial segment) [4]
-area of high density voltage gated channels
-membrane proteins
-sub-membranous cytoskeletal scaffolds
-determines the boundary between somatic dendritic and axonal compartments
What is the difference between bouton terminaux and bouton en passant
synapses located at the end of axon
synapses along axon
Explain what is meant by the probability of release [3]
-likelihood that action potential will leads to neurotransmitter release
-scale from 0-1 (0=no release)
-probability of release can change in a neurone
Compare high probability of release and low probability of release [4]
-depression/facilitation
-lots/few vesicles released in first action potential
-less/more vesicles available upon second action potential
-low/ high Pr in second
What causes a change in Pr? [2]
-changes in extracellular Ca+ concertation
-previous firing
What is the Schaffer collateral-commissural pathway [2]
- connection between CA1 and CA3 pyramidal neurones
-where electrode inserted to measure EPSP
What is paired pulse depression
-when the previous firing of the neurone causes a decrease in the strength of the next firing
