Neural Integration Flashcards
Are axo-dendritic connections usually excitatory or inhibitory?
Excitatory
Where do axo-dendritic connections synapse?
On the dendritic spine or shaft
Where do axo-somatic connections synapse?
On the cell bodies, sometimes the initial segment
How do axo-somatic connections affect transmission?
They release inhibitory GABA, and if on the initial segment, alter the firing pattern
Where do axo-axonal connections synapse?
Axon
What affect do axo-axonal connections have?
The can modulate and control neurotransmitter release by increasing or decreasing
How do axo-axonal connections control NT release?
Alter the permeability, of the neurone they are acting on, to K+ and Ca2+
If an axo-axonal connection decreases the K+ release in the neurone, what is the effect?
Ca2+ in the presynaptic terminal increases, so NT release is increased
How do axo-axonal connections reduce NT release?
They decrease the neurones permeability to Ca2+
Where are action potentials produced?
In the axon hillock/initial segment
Where do synaptic potentials integrate?
In the cell body/soma
What is convergence with respect to neural communication?
Many neurones can synapse on and influence one neurone
What is divergence with respect to neural transmission?
One neurone can synapse in many neurones
What are axon collaterals?
They are axon branches that allow for divergence
All synaptic potentials integrate to produce one if two responses, these are?
Excitatory postsynaptic potentials (EPSP) or inhibitory postsynaptic potentials (IPSP)
What is integration?
The summation of all the IPSP and EPSPs at the initial segment
What is temporal summation?
Summation over a short period of time
What is spatial summation?
Summation from multiple inputs across the membrane
How is the strength of stimulus portrayed by action potentials?
The action potential frequency increases for larger stimuli
How does an action potential travel along an axon?
Via self propagating depolarisation due to the neighbouring region undergoing Na+ influx = local currents
What is the normal directional transmission of action potentials called?
Orthodromic
How much can nerve velocities vary?
0.1m/s - 100m/s
Why do nerve velocities vary?
Due to varying axon diameters and myelination
