Membrane potential Flashcards
(36 cards)
What are the four classes of neurons?
Unipolar
Bipolar
Pseudo-unipolar
Multipolar
What is the function of glial cells?
Provide support for neurons
What is RMP and how is it formed?
Potential difference across cell membrane in resting condition
Cations and anions arranged along outer and inner surfaces
What molecules have a greater concentration in ECF than ICF?
Na+
Ca++
Cl-
HCO3-
Glucose
PO2
What molecules have a greater concentration in ICF than ECF?
K+
Mg++
PO4—
SO4-
AAs
Lipids
PCO2
How does a membrane potential form?
Separation of charges across cell membrane by leak channels?
What is the Nernst equation and what does it do?
EMF (mV) = (61/z) x log(conc inside/conc outside)
EMF = electromotive force
z = electrical charge of the ion (plus or minus)
It predicts membrane potential for a single ion at 98.6 F
What is the RMP of potassium?
-94 mV
What is the RMP of sodium?
+61 mV
What is the RMP of a neuron?
-70 mV
What maintains the RMP in cells and how?
Na/K ATPase
Pumps 3 sodium out and 2 potassium in against their concentration gradients
What is the Goldman equation
CnaiPna + CkiPk + CcloPcl
EMF (mV) = -61 x log —————————————-
CnaoPna + CkoPk + CcliPcl
What is membrane potential based on when there are multiple ions?
Polarity of each ion
Permeability of each ion
Concentration of each ion inside and outside the cell
How does hypoxia affect membrane potential?
It inhibits Na/K ATPase - causes membrane potential to rise
What is a graded potential?
Local, in response to a stimulus of lesser strength
What is a catelectrotonic potential?
Electrical stimulus evoking a depolarizing response
What is a anelectrotonic potential?
Electrical stimulus that causes hyperpolarization
What are the three properties of a graded potential?
Decremental conduction
Depolarizing or hyperpolarizing nature
Summation
What are the duration and amplitude of an action potential?
1 msec
-70mV to +35mV
What are the 7 stages of an action potential?
RMP
Threshold potential
Depolarization
Overshoot
Repolarization
Hyperpolarization
RMP
What is the absolute refractory period?
Period where another stimulus does not cause another action potential, from depolarization to repolarization
What is the relative refractory period?
During hyperpolarization until back to RMP, another stimulus can result in another AP
When to sodium channels open in relation to potassium channels during an action potential?
Sodium channels open first during repolarization
Potassium channels start to open around the upper peak of the AP, as sodium channels are beginning to close
What factors make propagation faster?
Myelin sheath - saltatory conduction
Increased axon diameter
