Lecture 6 Flashcards
Where is Na+ concentration the highest?
In the extracellular
Where is K+ concentration the highest?
In the intracellular
Where is Ca2+ concentration the highest?
In the extracellular
Where is the Cl- concentration the highest?
In the extracellular
What is Resting Membrane Potential?
Electrical charge separation across a membrane…at REST
What does a neuron do at Resting Potential?
Not triggered to release a neurotransmitter
What does a muscle cell do at Resting Potential?
Not triggered to produce a force
What is the mV of RMP
-80 to -60mV (depends on the cell)
- Cytosol vs.Extracellular Fluid
What does the resting membrane potential being negative mean?
It is in a “polarized state” - negative inside
What is Depolarization?
It loses polarity (switches to positive inside)
- Doing this by adding positively charged elements to the inside (Na+)
What is repolarization?
Restoring the polarized state (resting)
What is Hyperpolarization?
Making the cell “more” polarized.
What are the two types of biological signalling?
Electrical and chemical
What is the NERNST equation?
A measure of the equilibrium potential for ion, S
What is EN?
The voltage difference across a membrane to hold that ion in equilibrium.
What is the ENa?
+67mV
What is the Ek?
-98mV
What does the ENa and Ek values mean?
To hold sodium in equilibrium concentrations (145mM outside and 12mM inside), need a voltage difference of +67mV on the INSIDE of the cell.
What is a key concept?
Opposite charges attract, like charges repel (polarity)
What is the effect of a positive voltage inside the cell on Na+?
Has a repelling effect (keeps it outside the cell)
What is the effect of a negative voltage inside the cell on K+?
Has an attractive effect (keep it inside the cell)
What is the RMP for a skeletal muscle cell?
-65mV.
What is Potassium considered to be?
A negative ion at -75mV
(Why the inside of the cell is considered to be electronegative at RMP)
What is Sodium considered to be?
A positive ion at 55mV
(Why when the cell gets depolarized and sodium floods in, the cell turns positive)
Depolarizing Potential
Moves membrane towards threshold
Hyperpolarizing Threshold
Moving membrane away from the threshold
What is a Temporal Summation?
Increased frequency of stimulations from ONE NEURON
What is Spatial Summation?
Increased frequency of stimulations from MULTIPLE NEURONS
