44 Questions
What is the driving force for the diffusion of uncharged molecules?
Concentration gradient
What is the main factor that determines the diffusion potential?
Both concentration gradient and permeability of the membrane
What is the term for the potential that exactly balances the tendency of an ion to diffuse down its concentration gradient?
Equilibrium potential
What is the direction of the diffusion of Na+ ions in a solution with a higher concentration of Na+ and a lower concentration of Cl-?
From the side with higher Na+ concentration to the side with lower Cl- concentration
What is the term for the difference in electric potential between the interior and exterior of a biological cell?
Membrane potential
What is the purpose of the leak permeable channels in the membrane?
To maintain the resting membrane potential
Which of the following ions has the highest equilibrium potential?
Ca2+
What is the result of the diffusion of Na+ ions down its concentration gradient?
A diffusion potential is generated
What is the term for the potential that is maintained by a cell over a long period of time without significant change?
Resting potential
What is the condition required for the generation of a diffusion potential?
A concentration gradient of a charged solute
What is the effect of the movement of a few ions on the concentration of ions in bulk solution?
It does not cause a measurable change in concentration
What is the role of the concentration gradient in the diffusion of Na+ ions?
It drives the diffusion of Na+ ions
What is the equation used to calculate the equilibrium potential of an ion?
Nernst equation
What is the effect of the diffusion of Na+ ions on the membrane potential?
It depolarizes the membrane potential
What is the relationship between the concentration gradient and the diffusion potential?
The concentration gradient generates a diffusion potential
Which cells undergo controlled changes in their membrane potential?
Only neurons and muscle cells
What is the term for the potential that is generated by the movement of only a few ions?
Diffusion potential
What is the purpose of the theoretical membrane in the experiment?
To separate two solutions with different concentrations of Na+ and Cl-
What is the resting potential of nerve fibers when not transmitting nerve signals?
-70 millivolts more negative than the outside
What determines the resting potential of nerve cells?
Diffusion of potassium and sodium through the nerve cell membrane
What is the selectivity of the potassium leak channel for potassium ions compared to sodium ions?
100 times higher
What is the net effect of potassium diffusion on the resting potential?
It makes the potential more negative
What is the function of the sodium-potassium pump in maintaining the resting potential?
It pumps sodium out of the cell
Why do potassium ions move out of the cell through potassium leak channels?
Because of the negative charges inside the cell
What is the relative permeability of the nerve cell membrane to sodium and potassium ions?
Less permeable to sodium ions
What is the primary contributor to the resting potential of nerve cells?
Diffusion of potassium ions
What is the direction of net potassium ion movement through the potassium leak channel?
Out of the cell
What is the term for the moment before an action potential begins?
Resting stage
What is the term for the minimal membrane potential needed to trigger an action potential?
Threshold potential
What type of channels open during depolarization?
Voltage-gated sodium channels
What happens to the membrane potential during repolarization?
It becomes more negative
What is the term for the period when the neuron is in a state of hyperpolarization?
Relative refractory period
What happens to the voltage-gated sodium channels during the absolute refractory period?
They inactivate
What is the result of the rapid diffusion of potassium ions out of the cell?
Repolarization
What is the term for the time needed for voltage-gated sodium channels to revert to their resting state?
Absolute refractory period
What is the term for the state when the neuron is more negative than normal after an action potential?
Hyperpolarization
What is the primary mechanism by which an action potential propagates along the axon?
The depolarization of adjacent portions of the membrane
What is the primary factor that determines the resting membrane potential?
The unequal distribution of ions and the different permeability of the membrane
What is the role of the Na+/K+ ATPase pump in maintaining the resting membrane potential?
It pumps sodium ions out of the cell and potassium ions into the cell
What happens to the resting membrane potential when synaptic signals are received?
It can be changed
How does the Na+/K+ ATPase pump affect the movement of ions across the membrane?
It pumps sodium ions out of the cell and potassium ions into the cell against their concentration gradients
What is the direction of propagation of an action potential along the axon?
It travels in all directions away from the stimulus
What is the mechanism by which the resting membrane potential is maintained?
The unequal distribution of ions and the different permeability of the membrane
What is the effect of the leak channels on the resting membrane potential?
They allow the resting membrane potential to become more negative
This quiz covers the basics of muscle physiology, including how resting membrane potentials are generated and the phases of an action potential. Learn about equilibrium, diffusion, and ion channels.
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