Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
36 Cards in this Set
- Front
- Back
|
The resting membrane potential underlies which potentials?
|
All bioelectrical potentials
such as Action Potential, synaptic potential, receptor potential, field potential (EEG, EMG,ECG), and nerve conduction |
|
|
Resting membrane potential (Vm) for neurons?
|
-70 mV
|
|
|
Resting membrane potential (Vm) for muscles?
|
-90 mV
|
|
|
Factors contributing to resting membrane potential (Vm).
List 4 |
1. Selective Permeability of membrane
2. Active Transport of Na+ and K+ 3. Electrical Neutrality 4. Osmotic Neutrality |
|
|
What is the requirement for electrical neutrality?
|
[cations] - [anions] = 0
for both inside AND outside |
|
|
What is the requirement for osmotic neutrality?
|
[solutes] inside = [solutes] outside
|
|
|
Selective permeability of membrane is due to presence of what 3 things?
|
Ion channels
Passive transporters Active transporters |
|
|
Active transport of Na+ and K+ will:
- maintain what? - add what? - correct what? |
Maintains resting membrane potential (Vm)
Adds 3 mV to the Vm Corrects INTRAcellular osmolarity |
|
|
Gated ion channels contribution to resting membrane potential (Vm) relative to passive ion channels.
|
Contributes LITTLE to Vm
but can help to maintain it. |
|
|
What is the E(ion) @ 20 degrees C?
|
+/- 58.25 log [(ion outside) / (ion inside)]
|
|
|
What is the E(ion) @ 37 degrees C?
|
+/- 61.5 log [(ion outside) / (ion inside)]
|
|
|
Reversal potential:
- AKA - Define |
AKA - E(ion) or Equilibrium potential for specified ion.
It is the maximum potential due to diffusion of a SINGLE ionic species through a SINGLE TYPE of ion channel. OR of MULTIPLE ions through the SAME ion channel. |
|
|
When the concentration ratio is a fraction, the log is?
|
Negative
|
|
|
At the equilibrium potential (or reversal potential) what is the net flux over time?
|
NO net flux over time
|
|
|
What is the equilibrium potential for K+?
|
-90 mV
|
|
|
What is the equilibrium potential for Na+?
|
+60 mV
|
|
|
What is the equilibrium potential for Cl-?
|
-75 mV
|
|
|
What is the equilibrium potential for Calcium?
|
+120 mV
|
|
|
What is the equilibrium potential for cation channels?
|
roughly 0 mV
|
|
|
What is the driving force equation?
|
DF = Vm - Eion
|
|
|
What is the driving force for Na+ influx?
|
-70 mV - (+60 mV)
= -130 mV |
|
|
Increasing K+ concentration outside causes what?
why? |
DEpolarization
(in excitable cells, this causes hyperexcitability) b/c Vm seeks more positive E(k+) |
|
|
Low K+ concentrations outside causes what?
|
HYPERpolarization
|
|
|
Hyperpolarization can cause what symptom?
|
Paralysis
|
|
|
Why do small increases in Na+ concentration outside usually have little effect?
Is this the same with small increases in K+ concentration outside? |
B/c the pump can handle additional leakage.
No. Any changes in outside [K+] will change the membrane potential b/c K+ is through passive diffusion. |
|
|
Difference between Nernst equation and Goldman-Hodgkin-Katz equation? x3
|
Inclusion of P values
Reversed Cl- ratios Absence of z values |
|
|
What does the Goldman-Hodgkin-Katz equation describe?
|
Resting Membrane Potential (Vm) due to multiple ionic permeabilities.
|
|
|
Permeability of K+?
|
1
|
|
|
Permeability of Na+?
|
1/25 to 1/30
|
|
|
Permeability of Cl-?
|
1/10 to 1/20
|
|
|
Ratio seen for K+?
|
Concentration inside over outside = 40
|
|
|
Ratio seen for Na+?
|
Concentration outside over inside = 10
|
|
|
Ratio seen for Cl-?
|
Concentration outside over inside = 10 to 30
|
|
|
Why is the resting Vm not an equilibrium potential?
|
Because energy is required
|
|
|
What "stores" the "resting" Vm?
|
Membrane capacitance (Cm)
|
|
|
CONTRADICTION?
Resting membrane (Vm) vs Electrical Neutrality. Cells striving for electrical neutrality, but at the same time are happy with a resting membrane potential (e.g. -70 or -90). This is a contradiction, but why does it work? x2 |
1. Membrane capacitance
2. For each square cm of membrane, only 0.000002& of total K+ is imbalanced to generate Vm = |
