last 20 quesntions Flashcards
Asymmetrical synapses (Grays Type 1) are inhibitory or excitatory?
type 1: asymmetrical, excitatory, display a wide synaptic cleft, contain small round neurotransmitter storing vesicles within button w/ distinct postsynaptic density located at tip of dendritic spine. type 2: symmetric synapses, inhibitory, predominantly located at the dendritic shaft, exhibit smaller synaptic cleft
Which is true about both electrical and chemical synapses?
transmission relies on proteins embedded in the neuronal membranes
The resting membrane potential is primarily determined by potassium ions. Potassium is much more concentrated, however, inside the neuron than outside the neuron. Why, then, is the resting membrane potential negative inside rather than outside (Em = -65mV)
at rest, a net potassium current flows out of the cell
A dendrite with which properties have the highest length constant?
high membrane resistance and low internal resistance
Suppose a neuron was selectively permeable only to K+ ions (only K+ channels open). What would happen to the membrane potential of this cell if Na+ channels were now added to the cell and then opened?
Vm would depolarize
which of the following ions is at a higher concentration inside than outside a neuron during the height of the action potential?
K+
Ion X is negatively charged and has an equilibrium potential that is +50 mV. If channels that were selectively permeable to ion X were opened, what would happen to the membrane potential of the neuron? (assume it is a standard neuron at a resting membrane potential of -65 mV.)
it would depolarize
Assume that a neuron has a resting membrane potential of -65 mV and an ENa of +62 mV. If you could bring the membrane potential of this neuron up to +80 mV and open channels permeable to Na+ which way would Na flow?
Out of the cell!
Enough positive current is injected into a neuron to depolarize the membrane to threshold. which of the following would occur?
voltage-gated Na+ channels would open, Na+ ions would flow into the cell down their electrochemical gradient, and an action potential would generate
What does an axon that conducts action potentials via saltatory conduction have that is unique from axons that do not conduct via saltatory conduction?
myelin… saltatory conductions is the propagation of action potentials along myelinated axons from one node of Ranvier to the next- increases conduction velocity
Ion X is negatively charged and more concentrated inside than outside of the cell. therefore,…
EX is positive
If an axon at resting membrane potential were exposed to TTX (blocks Na channels) the result would be:
TTX will have little or no effect on the resting membrane potential
How would the mental pain caused, for instance, by an exam be encoded as a neuronal signal?
by the frequency of action potentials transmitted
If membrane potential of a cell is -65, which direction would K flow when K channels are opened?
out of the cell
If g, conductance, for an ion is 0, it is because:
no channels are open which gate that ion, the cell doesn’t contain that ion
