Small Circuits

Question 1

What do you need to know to tell whether a PSP is depolarizing or hyperpolarizing?

Answer 1

(a) the resting membrane potential of the cell, E_m
(b) the equilibrium of the ion(s) which flows thru the ligand channel, E_eq

Question 2

How do you obtain the resting membrane potential fo the cell? Em

Answer 2

(i) measuring the voltage difference between electrodes inserted inside and outside of the cell
(ii) using the GHK equation to calculate the potential

Question 3

How do you measure the equilibrium of the ion which flows through the ligand channel? E_eq

Answer 3

(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

Question 4

Choose from these options: >, <, =

Looking at this figure,

E_{eq ___} E_m

This cell is

Depolarizing / Hyperpolarizing/ No Change

Answer 4

E_eq > E_m

The equilibrium potential of the ion is greater than the resting membrane potential, so the cell is depolarizing.

Question 5

Choose from these options: >, <, =

Looking at this figure,

E_eq ___ E_m

This cell is

Depolarizing / Hyperpolarizing/ No Change

Answer 5

E_eq < E_m

The resting membrane potential is greater than the equilibrium potential of ions

The cell is hyperpolarized.

Question 6

Choose from these options: >, <, =

Looking at this figure,

E_eq ___ E_m

This cell is

Depolarizing / Hyperpolarizing/ No Change

Answer 6

E_eq = E_m

No change

Question 7

If the channel allows more than one type of ion to flow through it, use ____________.

Answer 7

Reversal potential (E_rev)

Question 8

How do you obtain the E_rev?

Also, what is the difference between E_rev and E_m?

Answer 8

(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.

Question 9

What are EPSP and IPSP?

Answer 9

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.

Question 10

What do you need to know to tell whether a PSP is excitatory or inhibitory?

Answer 10

(a) the resting membrane potential of the cell
(b) the equilibrium potential of the ion(s) which flow thru the ligand-gated channel, E_eq or E_rev
(c) the Action Potential Threshold

Question 11

Choose from these options: > , < , =

E_eq ___ Threshold ____ E_m

When the channel open the potential is:

depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory

Answer 11

E_eq > Threshold > E_m

The potential is depolarizing and excitatory

Question 12

Choose from these options: > , < , =

Threshold ___E_m ____ E_eq

When the channel open the potential is:

depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory

Answer 12

Threshold>E_m> Eeq

Hyperolarzing and inhibitory

Question 13

Choose from these options: > , < , =

Threshold ___E_eq ____ E_m

When the channel open the potential is:

depolarizing and excitatory/hyperpolarizing and inhibitory/depolarizing and inhibitory

Answer 13

Threshold >E_eq > E_m

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 E_eq

(less likely to fire A.P.)

Question 14

What are the properties that determine circuit behavior?

Hint: There are three

Answer 14

(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

Question 15

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 ___________.

Answer 15

Transmitter; receptor; ionic environment; excitatory; inhibitory

Question 16

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 16

The B neuron will fire the A.P. right after the revival A.P. from the presynaptic cell.

Question 17

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 17

Amplification –> Amplifies the A.P. received from neuron A and causes multiple A.P

Question 18

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 18

Spontaneous activity –> can fire A.P. by itself

Question 19

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 19

B is less likely to fire A.P. over time due to habituations

Question 20

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 20

No spontaneous activity in B

Question 21

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 21

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

Question 22

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 22

PIR is most common in real cells

Question 23

From the image and the properties of the circuit, determine the activity in Neuron B.

Answer 23

Whenever A is firing, B is not and vice versa

Question 24

How is circuit behavior determined?

Answer 24

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

Question 25

What are some examples of different interconnection that can give you the same firing pattern?

Hint: There are three different patterns.

Answer 25

Question 26

How is the amplification of a signal at a synapse be caused?

Answer 26

By the Post-synaptic being very close to the threshold

By different types of Post-synaptic receptors causing a prolonged response to transmitter release.

Question 27

What are the type of receptors that are used in the for amplification? (longer response to transmitter release)

Hint: think about the channel

Answer 27

(a) Glutamate ionotropic receptors the NDMA and AMPA receptor
(b) metabotropic receptors, thru second messengers

Question 28

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.

Answer 28

Large

1. The pre-synaptic terminal running out of available NTs after filling a number of times.
2. The pre-synaptic terminal Ca²⁺ levels becoming depleted due to the inactivation of V.G Ca²⁺ channels.

Question 29

Describe how the Post-inhibitory rebound lowers the threshold causing a higher chance of action potential.

Answer 29

Question 30

The motor control is arranged _________. Increasingly complex motor tasks are organized in successively higher centers.

Answer 30

Hierarchically

Question 31

What is a simple reflex?

Answer 31

Sensory neurons synapse with motor neurons in the spinal cord

Question 32

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)

Answer 32

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

Question 33

Higher levels of control in motor ______, ________, or _________.

)Generation of coordinated movement

Answer 33

High levels of control in the motor cortex, cerebellum, or basal ganglia.

Question 34

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

Answer 34

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

Question 35

What is the other example of a Central Pattern Generator?

Answer 35

Rhythmic alternatives generated by synaptic interaction between members of a neuronal network.

Question 36

Describe the activity in the flexor and extensor in the image. Properties are given

Answer 36

Question 37

Describe the activity in the flexor and extensor in the image. Properties are given

Answer 37

Question 38

Describe the activity in the flexor and extensor in the image. Properties are given

Answer 38

The interneuron taper the A.P. to make sure the membrane potential is always below the threshold, to stop your movement of your arm