Concept explainers
To draw:
A graph depicting the changes in potential during depolarization, repolarization, and hyperpolarization as compared to resting membrane potential.
Introduction:
All body cells have a membrane potential, which divides the positive and negative charges throughout the membrane. This potential is associated with uneven distribution of sodium (Na+), potassium (K+) and large intracellular protein anions, between the ICF (intracellular fluid) and the ECF (extracellular fluid) as well as to the plasma membrane's differential permeability. When the cell is electrically resting and does not produce electrical signal, the constant membrane potential is called resting membrane potential.
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Human Physiology: From Cells to Systems (MindTap Course List)
- Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)arrow_forwardDraw and label an action potential, indicating the ion movements responsible for the rising phase and the falling phase.arrow_forwardDefine an action potential.arrow_forward
- Define depolarization, repolarization, and hyperpolarization in terms of how it affects the membrane potential of an excitable cell.arrow_forwardIf: membrane potential=-70mV, ENa=+60mV, and Ex=-90mV, consider which directions Na+ and K+ will leak across the membrane. If both ions are crossing the membrane, what is the most important factor in determining whether membrane potential will become more positive or more negative?arrow_forwardWhat ion is the major influence on the resting membrane potential? Explain its role.arrow_forward
- Describe the ion movement across the cell membrane during the following stages: resting potential, threshold potential, depolarization, repolarization.arrow_forwardwhich of the following would be true (more than one can be true)? a) summation of A and X would reach threshold b) summation of C and A would be a graded potential c) stimulation by A would depolarize cell d) stimulation by B would be a subthreshold depolarization e) summation of B and C would be a graded potential with the net value of 12 mV depolarizationarrow_forwardThe following is a graph of membrane potential over time during an action potential. At which labeled point, A-D, would permeability to potassium (K+) be the greatest? A) B) C) D)arrow_forward
- How do depolarize, repolarize, and hyperpolarize describe the direction of changes in the membrane potential relative to the resting potential in an excitable cell?arrow_forwardWhat is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 23 mM at 20 ∘C ?arrow_forwardWhat is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 23 mM at 20 ∘C ?arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage LearningHuman Biology (MindTap Course List)BiologyISBN:9781305112100Author:Cecie Starr, Beverly McMillanPublisher:Cengage Learning