Lecture 10 Synapses and Synpatic function Flashcards
what is a Synapse
site of communication between neurons
what are the components of synapse
- presynaptic neuron
- post synaptic neuron
- synaptic cleft
What is Presynaptic Neuron Structure
- Axon terminal
- contains synaptc vessicles
- contain voltage gated channels
what is the presynaptic function ?
transmit signal
what are synaptic vessicles
hold the neurotransmitters
what is the Postsynaptic neuron structure
usually dendrites or soma
contain receptors for NT
what is the function of the postsynaptic neuron
receives the signal
what is the structure of the synaptic cleft?
narrow extracellular space between neurons
what is the function of synaptic cleft ?
allow diffusion of NT
communication steps across a synapse
- Action potential arrives at axon terminal
2 voltage gated Ca+ channels open - Ca2+ flows in –> exocytsis of synaptic vessicles
- NT diffuse across cleft –> bind to receptors
- Postsynaptic cell responds
- response is stopped when NT is removed from cleft
- degradation
- reuptake
-diffusion
what are the effects of Neurotransmitters
Change membrane potential in postsynaptic cell
- excitatory
- inhibitory
what is Excitatory
Excitatory Postsynaptic Potential (EPSP)
Depoloarizing
NT bind to receptors triggering
-Na+ channels open
-Na+ moves into the cell–> depolarizing
Moves membrane potential closer to threshold
What is Inhibitory
Inhibitory Postsynaptic potential (IPSP)
Hyperpolarizing
-NT binds receptors triggering
1. k+ channels open –> K+ moves out of the cell –> hyperpolarizing
2. Cl- channels to oopen
- Cl- move into the cell —> hyperpolarize
move the membrane potential further from threshold
-membrane stabilizes
what is divergence
one presynaptic neuron–> several post synaptic neurons
What is convergence
several presynaptic heuronss—> one post synaptic neuron
what are graded potentials
small changes in membrane potential due to ion channels opening/closing in response to stimuli
what are the properties of graded potentials
- graded
- decremental
- depolarizing or hyperpolarizing
- summation
what is graded
change in membrane potential reflects strenght of stimulus
- weak stimuli–> small change
- strong stimuli–> large change
what is decremental
change dissipates with distance from the stimulus
What is depolarizing and hyperpolarizing
IPSP= hyperpolarizing EPSP= depolarizing
what is summation
can combine effects of stimuli
- add
- cancel
what are the types of summation
temporal: same stimulus
repreated close together in time
spatial: different stimuli
overlap in time
what is the purpose of graded potentials
graded potentials determine if an action potential will ocurr or not
what is the rule of graded potentials
if the membrane potential at the axon hilock depolarized above the threshold –> AP
