Small Circuits Flashcards
What do you need to know to tell whether a PSP is depolarizing or hyperpolarizing?
(a) the resting membrane potential of the cell, Em
(b) the equilibrium of the ion(s) which flows thru the ligand channel, Eeq
How do you obtain the resting membrane potential fo the cell? Em
(i) measuring the voltage difference between electrodes inserted inside and outside of the cell
(ii) using the GHK equation to calculate the potential
How do you measure the equilibrium of the ion which flows through the ligand channel? Eeq
(i) using the patch-clamp technique by applying ligands to open channels and finding out the voltage at which no current flows
(ii) using Nernst equation to calculate the potential
Choose from these options: >, <, =
Looking at this figure,
Eeq ___ Em
This cell is
Depolarizing / Hyperpolarizing/ No Change
Eeq > Em
The equilibrium potential of the ion is greater than the resting membrane potential, so the cell is depolarizing.
Choose from these options: >, <, =
Looking at this figure,
Eeq ___ Em
This cell is
Depolarizing / Hyperpolarizing/ No Change
Eeq < Em
The resting membrane potential is greater than the equilibrium potential of ions
The cell is hyperpolarized.
Choose from these options: >, <, =
Looking at this figure,
Eeq ___ Em
This cell is
Depolarizing / Hyperpolarizing/ No Change
Eeq = Em
No change
If the channel allows more than one type of ion to flow through it, use ____________.
Reversal potential (Erev)
How do you obtain the Erev?
Also, what is the difference between Erev and Em?
(a) Can be obtained by using GHK equation
(B) Reversal potential lets multiple ions flow through the channel, while equilibrium potential only lets one ion flow through the channel.
What are EPSP and IPSP?
EPSP, excitatory postsynaptic potential makes it more likely for the cell to fire an Action Potential.
IPSP, inhibitory postsynaptic potential makes it less likely for the cell to fire an Action Potential.
What do you need to know to tell whether a PSP is excitatory or inhibitory?
(a) the resting membrane potential of the cell
(b) the equilibrium potential of the ion(s) which flow thru the ligand-gated channel, Eeq or Erev
(c) the Action Potential Threshold
Choose from these options: > , < , =
Eeq ___ Threshold ____ Em
When the channel open the potential is:
depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory
Eeq > Threshold > Em
The potential is depolarizing and excitatory
Choose from these options: > , < , =
Threshold ___Em ____ Eeq
When the channel open the potential is:
depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory
Threshold>Em> Eeq
Hyperolarzing and inhibitory
Choose from these options: > , < , =
Threshold ___Eeq ____ Em
When the channel open the potential is:
depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory
Threshold >Eeq > Em
The potential of the cell is depolarizing and Inhibitory
When the A.P. comes in, the channel is going to pull the membrane potential done to Eeq
(less likely to fire A.P.)
What are the properties that determine circuit behavior?
Hint: There are three
(a) Connectivity: what neurons are connected to each other
(b) Synaptic Properties: type of NTs and their receptors, NT limits, PSP and second messengers effects
(c) Intrinsic cellular properties: receptors and channels, endogenous spontaneous activities
The _________release by a pre-syanptic cell and the _________ on the postsynaptic cell combined with the ___________ inside and outside of the cell determines whether a connection is _________ or ___________.
Transmitter; receptor; ionic environment; excitatory; inhibitory
From the image and the properties of the circuit, determine the activity in Neuron B.
The B neuron will fire the A.P. right after the revival A.P. from the presynaptic cell.
From the image and the properties of the circuit, determine the activity in Neuron B.
Amplification –> Amplifies the A.P. received from neuron A and causes multiple A.P
From the image and the properties of the circuit, determine the activity in Neuron B.
Spontaneous activity –> can fire A.P. by itself
From the image and the properties of the circuit, determine the activity in Neuron B.
B is less likely to fire A.P. over time due to habituations
From the image and the properties of the circuit, determine the activity in Neuron B.
No spontaneous activity in B
From the image and the properties of the circuit, determine the activity in Neuron B.
When neuron A fire the A.P. there will be a small period of inhibition in neuron B and then return to rapid spikes of A.P. –> the cycle continues
From the image and the properties of the circuit, determine the activity in Neuron B.
PIR is most common in real cells
From the image and the properties of the circuit, determine the activity in Neuron B.
Whenever A is firing, B is not and vice versa
How is circuit behavior determined?
By Connectivity, synaptic properties, and intrinsic cellular properties.
(a) Different interconnection can give you the same firing pattern.
(b) The same interconnection can give you different firing pattern
What are some examples of different interconnection that can give you the same firing pattern?
Hint: There are three different patterns.
How is the amplification of a signal at a synapse be caused?
By the Post-synaptic being very close to the threshold
By different types of Post-synaptic receptors causing a prolonged response to transmitter release.
What are the type of receptors that are used in the for amplification? (longer response to transmitter release)
Hint: think about the channel
(a) Glutamate ionotropic receptors the NDMA and AMPA receptor
(b) metabotropic receptors, thru second messengers
Habituation can be caused by a (small/large) number of mechanism.
One simple mechanism is the _______________________ after firing a number of times.
Another is the ________________ levels becoming ____________ due to inactivation of V.G. Ca2+ channels.
Large
- The pre-synaptic terminal running out of available NTs after filling a number of times.
- The pre-synaptic terminal Ca2+ levels becoming depleted due to the inactivation of V.G Ca2+ channels.
Describe how the Post-inhibitory rebound lowers the threshold causing a higher chance of action potential.
The motor control is arranged _________. Increasingly complex motor tasks are organized in successively higher centers.
Hierarchically
What is a simple reflex?
Sensory neurons synapse with motor neurons in the spinal cord
central pattern generators
Networks of ___________ in the spinal cord or brainstem to coordinate the interplay of multiple antagonistic motor groups
(absence of sensory feedback)
Using ______ to move different set of muscle –> fire AP __________ (not the same time) to move the flexors and extensions
(Swimming Mechaism in the sea slug)
Networks of interneurons in the spinal cord or brainstem to coordinate the interplay of multiple antagonistic motor groups
Using neurons to move a different set of muscle –> fire A.P. alternative (not the same time) to move the flexors and extensions
Higher levels of control in motor ______, ________, or _________.
)Generation of coordinated movement
High levels of control in the motor cortex, cerebellum, or basal ganglia.
Rhythmic alternations generated in a single neuron; a pacemaker cell.
Pacemaker cells: The cell is _________________.
Depolarization open ________ channels, increased _____ and open _________channels. _____ flows out of the cell
The cell hyperpolarizes below the A.P. threshold and stops firing.
____ channels are then inactive. _____________ channels close, depolarizing cell membranes potentials.
The cycle then begins again.
Hint: Look at the image
In Neuron A, of the figure
(i) Pacemaker cells: The cell is spontaneously active
(ii) Depolarization open V.G. Ca2+ channels.
Increased Ca2+ open Ca2+ dependent K+ channel
K+ flows out of the cell
The cell hyperpolarizes below the A.P. threshold and stops firing.
(iii) Ca2+ channels are then inactive. Ca2+ dependent K+ channels close, depolarizing cell membranes potential.
(iv) the cycle then begins again
What is the other example of a Central Pattern Generator?
Rhythmic alternatives generated by synaptic interaction between members of a neuronal network.
Describe the activity in the flexor and extensor in the image. Properties are given
Describe the activity in the flexor and extensor in the image. Properties are given
Describe the activity in the flexor and extensor in the image. Properties are given
The interneuron taper the A.P. to make sure the membrane potential is always below the threshold, to stop your movement of your arm
