Neurophysiology
Describe how the Na/K pump works, including concentration gradients, ion movements, and what type of transport it uses. Does the Na/K pump establish Resting Membrane Potential (RMP)?
Moves 3 Na out and 2 K in...these ions are going UP/AGAINST their concentration gradients (b/c they're moving to an area where there's already a lot of them). Active transport is used b/c we're pumping ions against their concentration gradients, so ATP is required. Na/K pump establishes RMP
How does axon diameter and myelination affect conduction velocity?
Larger diameter decreases resistance of AP propagation, and myelination covers up the leakage channels so the voltage doesn't decay, making the AP propogate faster down the axon.
What is the difference between an electrical synapse and a chemical synapse?
An electrical synapse consists of EPSPs ONLY. They transmit APs through their gap junctions (common in the embryonic development of the brain). Chemical synapses are much more common. They go through the steps we learned at the NMJ...however, the type of NT will vary (could be EPSP or IPSP) and thus, the type of ligand gated channel they bind to will vary.
What is the gyrus, sulcus, and fissure
Gyrus - ridge or fold on surface of cerebral cortex
Sulcus - groove or depression between these folds
Fissure - deep sulcus
Describe how leakage Na and K channels work, including their type of transport, where they move ions, concentration gradients. Are there more Na or K leakage channels on the membrane?
Leakage channels use passive diffusion (no ATP) for their transport and move ions down/toward their concentration gradients. There are more K leakage channels on the membrane because the membrane is more permeable to K ions.
What are the specific EPSPs we've talked about, and what are the channel(s) that they will bind to on postsynaptic neurons?
Glutamate & ACh
These will bind to ligand gated Na channels.
Describe temporal and spatial summation
Temporal summation is increasing the frequency of APs firing, thus building up EPSPs to threshold or IPSPs away from threshold. Spatial summation is increasing the number of neurons synapsing with the postsynaptic neuron, which sums the EPSPs or IPSPs released by the presynaptic neuron.
During the depolarization phase (after threshold), is the inactivation gate and activation gate open or closed on voltage gated Na channels?
They are both open
What are the specific IPSPs we've talked about, and what are the channel(s) that they will bind to on postsynaptic neurons?
Glycine and GABA
These will bind to ligand gated Cl and K channels (Cl influx [negative ion] or K efflux)
What is the difference between fast synaptic responses (ionotropic receptors) and slow synaptic responses (metabotropic receptors)?
Ionotropic receptors open right away when a NT binds to them. Metabotropic receptors go through a G-protein pathway and a secondary receptor.
During hyperpolarization, describe the positioning of the activation gate and inactivation gate on voltage gated sodium channels
Some VG Na channels have fully reset back to their original positions (Inactivation gate off, activation gate closed) while others are still in their inactivation state. K still flowing out.
Describe continuous and saltatory conduction
Continuous conduction occurs on unmyelinated axons. This is where you have to continuously generate the AP over and over again. Saltatory conduction occurs on myelinated axons. This is where the myelin covers leakage channels so the voltage doesn't decay down the axon, allowing for the AP to essentially "skip" over the myelin and only regenerate at the nodes of ranvier.
VG Ca channels open, Ca binds to spade proteins on vessicles, vessicles release NTs into synaptic cleft, NTs bind to ligand gated channels on postsynaptic dendrites (ligand gated Na channels if EPSP or ligand gated K/Cl channels if IPSP), threshold is either built up to via temporal/spatial summation, or it is hyperpolarized.
Describe the whole process of action potential generation, including concentration gradients, phases of the graph, and respective positioning of the activation and inactivation gates at each phase.
You can do this.
Describe absolute and relative refractory periods
The absolute refractory period is when it's impossible to generate a new AP because one is already going, and once you hit the repolarization phase, the VG Na channels are in their "inactivation" state. The relative refractory period is when it's possible to generate a new AP, but you need a STRONG stimulus to do so b/c some VG Na channels are still in the inactivated state, giving you less of them to work with, and K is still effluxing, making it harder to hit threshold.