Quiz 1 (Cooper)

Question 1

What is the formula for the time constant?

Answer 1

τ = Cm*Rin

Question 2

What is the formula for the membrane capacitance?

Answer 2

Cm = 1 µF/cm2 = 10^-2 F/m^2

Question 3

What is Faraday’s cste?

Answer 3

5* 10^18 ions (Na+ or K+)

Question 4

How can Rin for a firing synapse be found?

Answer 4

1/Rin(syn) = Gsyn + 1/Rin = 1/Rsyn + 1/Rin

Rin(syn) = Rsyn*Rin/ (Rsyn + Rin)

Question 5

What is the formula for the ∆Q change in charges?

Answer 5

∆Q = Cm * ∆Vm

Question 6

What is the formula for then change in membrane potential with time?

Answer 6

∆Vm (t) = Vss[ 1 - e^(-t/τ)]

Question 7

How does the size of the cell impact the resistance input and the firing ease of a cell?

Answer 7

Bigger cell = more channels = higher G = lower Rin = more current needed to fire AP = integrators

Smaller cell = less channels = lower G = higher Rin = less current needed to fire AP = relay cells

Question 8

What are the 2 types of membrane currents?

Answer 8

Ic = Capacity current = responds to RATE of change in voltage (faster at start of AP where there is the synapse) (going to capacitor)

Im = Ionic current responds to change in voltage (channels elsewhere in cell that are always open?) (going to resistor)

Question 9

What is Vss?

Answer 9

Vss = Isyn * Rin(syn)
when EPSP
(Im = total membran current)

Question 10

What is the equation for decay of synaptic amplitude along dendrites?

Answer 10

∆Vx = V0 e^(-x/λ)

Question 11

What is the equation to find λ, the space constant?

Answer 11

λ = sqrt[ (Rm*r)/(2φ) ] um

Rm = specific membrane resistance in Ω-cm2
φ = resistivity of membrane

Question 12

What is Ohm’s law?

Answer 12

∆Vm = ∆I*Rin

Question 13

What is the formula to find the membrane equilibrium of Non-specific channels?

Answer 13

Erev = (Ek + Ena)/2

Question 14

What are the 2 types of excitatory synapses?

Answer 14

Nicotinic AChR
Ionotropic Glutamergic receptors
*Use E-rev to find current in them
*Inward current, they depolarize the cell

Question 15

What are the 2 types of excitatory synapses?

Answer 15

GABAergic
Glycinergic
*Use Ecl to find current
Cl comes in (outward positive current hyperpolarizes the cell)

Question 16

How many L is 1 cm3?

Answer 16

1 mL

Question 17

When does t = τ??

Answer 17

When Vm = 0.63 Vss

Question 18

How can you find the conductance if it is not given?

Answer 18

I = g(Vm - E)
isolate G (Simens = 1/Ohms)

Question 19

What is the formula to find Vm(t) during the decay of an AP?

Answer 19

∆ Vm (t) = V * e^(-t/τ)

Question 20

What are the names of the 2 main Ionotropic glutamate receptors?
What are their antagonists?

Answer 20

AMPA/Kainate (Na+, K+) - Antagonist = CNQX
AMPA = fast rising, fast decay

NMDA receptors (Na+, K+, Ca2+) and has an Mg2+ blocker on it that has to be pushed - Antagonist = D-APV
NMDA = Slower opening bc depolarization needed for Mg2+ to leave

Question 21

What are the Na and K+ blockers?

Answer 21

Na channels (AMPA) blocked by TTX

K+ channels (NMDA) blocked by TEA

Question 22

What is Avogadro’s number?

Answer 22

6.022*10^23

Question 23

How what is another definition for current (Ampers)?

Answer 23

Ampers = Coulombs/second