L9: Neurons & Neuronal: Synapses Flashcards
Function of a synapse
Allows a neuron to pass an electrical or chemical signal to another neuron
3 types of synapses
1) Axodendritic
2) Axosomatic
3) Axoaxonic
What is an axosomatic synapse?
Axon of 1 neuron attaches to the cell body of another neuron
What is an axodendritic synapse?
Axon of 1 neuron terminates on the dendrite of another neuron
What is an axoaxonic synapse?
Axons of 2 different neurons meet
What is a electrical synapse?
Neurotransmitter-mediated communication
What is a chemical synapse?
Direct connection via gap junctions allowing ion flow
What are gap junctions?
Allow the exchange of ions between cells
Components of the neuron, and what are their functions?
1) Dendrite: Receive signals
2) Cell Body (Soma): Process information
3) Axon: Transport signals to next neuron
Describe synaptic communication
1) Neuron at resting potential
2) Voltage-gated Ca2+ channels open, influx
3) Ca2+ triggers exocytosis
4) NT diffuses along cleft & activates post-synaptic cell
What is a graded potential?
Changes in membrane potential graded depending on strength of stimulus
What is spatial summation of synaptic communication based on?
Location
What is spatial summation?
Multiple presynaptic neurons firing. at the same time
What is temporal summation of synaptic communication based on?
Relying how quickly a nerve fires
What is temporal summation?
1 presynaptic neuron firing repeatedly in a short time
How many nerves are involved in temporal summation?
1 or 2
What happens if 2 nerves in temporal summation fire at different times?
No AP triggered
Excitatory synapse
Neurotransmitter:
Effect:
Ion movement:
Outcome
Glutamate
Excitatory
Ion Movement: Na+ enter post-synaptic neuron
Outcome: Depolarisation increases chances of an AP firing
Inhibitory Synapse
Neurotransmitter
Effect
Ion movement
Outcome
GABA
Inhibitory
Cl- enter post-synaptic neuron
Hyperpolarisation makes neuron less likely to fire an AP
What happens in 2 nerves in temporal summation fire at the same time?
Fire an AP
What is an excitatory postsynaptic potential (EPSP)?
Postsynaptic potential that makes postsynaptic neuron more likely to fire an AP
What is an inhibitory postsynaptic potential (IPSP)?
Makes postsynaptic neuron less likely to generate an AP
How to EPSP and ISPS act against each other?
Cancel each other out
Two types of receptors
1) Ionotropic
2) Metabotropic
What are ionotropic receptors?
Ligand-gated ion channels that open in response to the binding of a neurotransmitter
What are metabotropic receptors?
Require G proteins to modulate activity in neurons but slow acting
Examples of IPSP & EPSP in ionotropic receptors
Na+ -> IPSP
Cl-/K+ -> EPSP
