Physiology Flashcards
Local response (electric potential)
A stimulus causes a cell membrane to increase permeability to Na+ but not enough to cause an action potential. Still decremental.
Hodgkin Cycle
Regenerative increase in membrane conductance to Na+ that occurs when threshold is reached
What about myelinated fibers make them good at conducting action potentials?
The myelin sheath has high resistance so the action potential (charge) will travel within the axoplasm rather than the membrane until it reaches the next node. This is FAST BABY
Which is faster an electric or action potential? Which is decremental?
Electric is faster and also decremental
How are fiber diameter and threshold related?
As fiber diameter increases, threshold potential decreases
Where are Na+ and K+ channels located in relation to the myelin sheath? What happens if the myelin sheath breaks down, then?
Na+ are far more present in the internodal regions while the K+ channels are beneath the myelin sheath. Because the distribution is not equal, when myelin breaks down it can disrupt or even stop action potentials
What is the Nernst potential?
The membrane potential based on a given ion when the concentration and electrical gradients are in equilibrium
Explain the principle behind the Goldman-Hodgkin-Katz equation
The overall membrane potential based on the Nernst potential and relative permeability of each ion
Which is more important for membrane potentials, changes in permeability or changes in ion concentration?
Permeability is much more important because even minuscule changes in concentration can lead to large changes in charge
Are inhibitory or excitatory post-synaptic potentials conducted decrementally?
Yessir
Which electric properties of a membrane determine its response to an electric stimulus?
Resistance and capacitance
What are the 4 excitable cells?
Neurons and the 3 types of muscle cells
