Neuronal Properties
What is the voltage inside a neuron at rest?
(-70) - (-60) mV
Which of these four ions has a higher concentration inside the neuronal membrane than outside of it? (Cl, Na, K, Ca)
K and all others are higher outside the membrane.
Magic Number?
6 x 4
(Only applies to the v-gated superfamily...REMEMBER THAT)
What is the difference between an electrical and chemical synapse?
chemical uses NT, electrical propogates AP through gap junctions
What are the three necessary chemical components to immunohistochemistry?
1- NT of interest
2- antibody attached to NT
3- visible marker attached to antibody
Order the following organisms by neuron count (ascending): zebrafish, mouse, human, fruit fly
FF, zF, M, H
What is the main contributor to the resting neuronal membrane potential?
K+ leak channels
What mechanism by which an AP propagates?
Stimulus creates changes in voltage which activates V-gated Na+ channels, which make cell more positive, which makes nearby membrane do the same and so on
Describe axosomatic, axodendritic, and axoaxonic.
A->S
A->D
A->A
Describe in situ hybridization and its purpose.
radioactively labelled mRNA probe which attaches to mRNA of interest
infer which proteins are being expressed by the number of mRNA present...mRNA is upstream of protein synthesis
Name the Three Structures of the Cytoskeleton
MT's
MF's
Neurofilaments
Describe a peptide bond.
(O)C-N(H) or something like this
Which toxins would I use, in conjunction with a voltage clamp, to find the conductance of a sodium channel?
Double points for all Three possible answers
acceptable answers: TEA, Dendrototoxin, Apamin
Describe the difference between receptor agonists and antoagonists.
agonists - mimic NT action
antagonists - blocks NT action
Describe optogenetics.
Use light to active membrane channels
Name the five components of a neuron
Dendrites, soma, axon hillock, axon, synaptic terminal
Describe the way by which a sodium ion passes through the membrane.
It is hydrated by exactly one water molecule and passes through a size selectivity filter of the sodium channel (leak or V-gated)
What are the balancing factors that contribute to the distances between the Nodes of Ranvier?
Less leaks will make the nodes as far apart as possible but the change in voltage felt by V-gate Na+ channels is higher the closer it is to the node
AA's - glutamate, GABA, glycine
Amines - DA, ACh, histamine, Norep.
Neuropeptides - dynorphin, enkephalins, (endogenous opioids), oxytocin, vasopressin, neurotensin
Gases - NO
Fatty Acids - anandamide (MJ)
Describe in full, why a marathon runner might lose motor control near the end of a race if you know that sodium is in sweat.
NA+ leaving means lower concentration outside the cell, therefore less chemical gradient for Na+ during an AP and might not reach threshold for AP's
Describe a current clamp
record the voltage of a neuron at varying currents
When do you use the Nernst Eqn and when do you use the Goldmann Eqn. (Think about the unknowns)
Nernst -> when finding the eqm ion potential
Goldmann -> when predicting the neuronal membrane potential
What would be the consequence of not having a delayed rectifier?
Slower repolarization, no hyperpolarization, wider AP, Slower absolute refractory period
Describe shunting inhibition.
inhibitory synapse which blocks the excitatory action of a synapse that is upstream
What would happen if the V-gated Na+ channels's ball and chain mechanism acted faster than it currently does?
Na+ channels would stay open for less time, therefore the neuron would not become as positive and would not propagate the AP for as long for every stimulus and/or not reach threshold for an AP