Synaptic Transmission Flashcards
Define synapse?
Junction between 2 neurons
State 2 diff types synapses?
Electrical
Chemical
What is excitatory synapse?
Membrane potential of postsynaptic neuron depolarised
What is inhibitory synapse?
Membrane potential of postsynaptic neuron hyperpolarised or stabilised at resting potential
What 5 processes synaptic transmission?
1) Manufacture
2) Storage- vesicles
3) Release- action potential
4) Interaction with post-synaptic receptors
5) Inactivation- breakdown or reuptake
Does all or some neurotransmitter bind?
Small fraction
What occurs when neurotransmitters bind?
Excitatory
Inhibitory
Depolarisation or hyperpolarisation (depending on channel type)
Depolarisation- excitatory channels (EPSPs)
Hyperpolarisation- inhibitory channels (IPSPs
What are 2 types of summation?
Temporal summation- input signals arrive from same
presynaptic cells at different times
Spatial summation- simultaneous stimulation by several presynaptic neurons
How are neurotransmitters inactivated/removed from synaptic cleft? (3)
1) Actively transported back to presynaptic axon terminal-
reuptake
2) Diffuse away from receptor site
3)Enzymatically transformed into inactive substances
What is most common synapse? Chemical or electrical?
Chemical
In chemical synapse what joins plasma membranes of pre and post synaptic cells?
Synaptic cleft
What holds synaptic vesicle and neurotransmitter?
Axon ends in axon terminal
Label
In chemical synapses what prevents direct propogation of current?
Synaptic cleft
Flow of chemical synapse
What cell is essential for reuptake of neurotransmitters?
Astrocyte
Function of astrocyte?
Eseential reuptake of neurotransmitters
What joins plasma membranes of pre and postsynaptic cells in electrical synapse?
Gap junctions
What is faster electrical or chemical synapases?
Electrical
Where is electrical synapses found?
Brainstem neurones
Hypothalamus
Hormone secretion
State process neurotransmitter release?
1) AP reaches presynaptic terminal
2) Voltage gated calcium channels open
3) Vesicles move to release sites- fuse with pre-synaptic membrane (exocytosis)
4) Neurotransmitter diffuses across synaptic cleft
5) Neurotransmitter attaches to receptor site on post-synaptic neuron
6) Receptor transmits signal
7) Neurotransmitter inactivated
What are 2 types of post synaptic receptors?
Ionotropic receptor
Metabotropic receptors
Ionotropic receptor
State:
Type
Response
Speed response
Length response
Type- Ligand gated ion channels
Response- Allow ion flux- change cell voltage
Speed response- Rapid
Length response- Short acting
Metabotropic receptor
State:
Type
Response
Speed response
Length response
State:
Type- G protein coupled receptor
Response- Act through secondary messenger
- Cause cellular effect
Speed response- Slow
Length response- Prolonged
What type of receptors have ligand gated ion channels?
Ionotropic receptors
What type of receptors have G Protein coupled receptors?
Metabotropic receptors
What receptors change cell voltage?
Ionotropic receptors
What receptors act as secondary messengers?
Metabotropic receptors
What receptors cause rapid response?
Ionotropic receptors
What receptors cause slow response?
Metabotropic receptors
What receptors causes rapid response?
Ionotropic receptor
