potential

Examples of potential in the following topics:

• Standard Reduction Potentials

  • Reduction potential (also known as redox potential, oxidation/reduction potential, or Eh) measures the tendency of a chemical species to acquire electrons and thereby be reduced.
  • Reduction potential is measured in volts (V) or millivolts (mV).
  • Each species has its own intrinsic reduction potential.
  • Historically, many countries, including the United States and Canada, used standard oxidation potentials rather than reduction potentials in their calculations.
  • However, because these can also be referred to as "redox potentials," the terms "reduction potentials" and "oxidation potentials" are preferred by the IUPAC.

• Postsynaptic Potentials and Their Integration at the Synapse

  • Postsynaptic potentials are excitatory or inhibitory changes in the graded membrane potential in the postsynaptic terminal of a chemical synapse.
  • Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse.
  • Postsynaptic potentials are graded potentials and should not be confused with action potentials, although their function is to initiate or inhibit action potentials.
  • This is an excitatory postsynaptic potential (EPSP) as it brings the neuron's potential closer to its firing threshold (about -50mV).
  • This is an inhibitory postsynaptic potential (IPSP).

• The Action Potential and Propagation

  • Action potential is a brief reversal of membrane potential where the membrane potential changes from -70mV to +30mV.
  • When the membrane potential of the axon hillock of a neuron reaches threshold, a rapid change in membrane potential occurs in the form of an action potential.
  • This moving change in membrane potential has three phases.
  • Schematic and B. actual action potential recordings.
  • The action potential is a clear example of how changes in membrane potential can act as a signal.

• Water and Solute Potential

  • Water potential is the measure of potential energy in water and drives the movement of water through plants.
  • Water potential is a measure of the potential energy in water, or the difference in potential energy between a given water sample and pure water (at atmospheric pressure and ambient temperature).
  • Solute potential (Ψs), also called osmotic potential, is negative in a plant cell and zero in distilled water.
  • Solutes reduce water potential (resulting in a negative Ψw) by consuming some of the potential energy available in the water.
  • This is why solute potential is sometimes called osmotic potential.

• Nerve Impulse Transmission within a Neuron: Action Potential

  • The action potential travels down the neuron as Na+ channels open.
  • Action potentials are considered an "all-or nothing" event.
  • Once the threshold potential is reached, the neuron completely depolarizes.
  • The diffusion of K+ out of the cell hyperpolarizes the cell, making the membrane potential more negative than the cell's normal resting potential.
  • At this point, the sodium channels return to their resting state, ready to open again if the membrane potential again exceeds the threshold potential.

• Membrane Potentials as Signals

  • In neurons, a sufficiently large depolarization can evoke an action potential in which the membrane potential changes rapidly.
  • Membrane potential (also transmembrane potential or membrane voltage) is the difference in electrical potential between the interior and the exterior of a biological cell.
  • The membrane potential has two basic functions.
  • Schematic and B. actual action potential recordings.
  • The action potential is a clear example of how changes in membrane potential can act as a signal.

• Gravity

  • The potential energy due to elevated positions is called gravitational potential energy, evidenced, for example, by water held in an elevated reservoir or behind a dam (as an example, shows Hoover Dam).
  • (The surface will be the zero point of the potential energy. ) We can express the potential energy (gravitational potential energy) as:
  • For this choice, the potential at infinity is defined as 0.
  • Hoover dam uses the stored gravitational potential energy to generate electricity.
  • Generate an equation that can be used to express the gravitational potential energy near the earth

• Potential Energy Curves and Equipotentials

  • A potential energy curve plots potential energy as a function of position; equipotential lines trace lines of equal potential energy.
  • A potential energy curve plots the potential energy of an object as a function of that object's position.
  • The utility of a potential energy curve is that we can quickly determine the potential energy of the object in question at a given position.
  • Equipotential lines trace lines of equal potential energy.
  • Work (W) is a measure of the change in potential energy (ΔPE): W = -ΔPE.

• Resting Membrane Potentials

  • The potential difference in a resting neuron is called the resting membrane potential.
  • The potential difference in a resting neuron is called the resting membrane potential.
  • The resting membrane potential exists only across the membrane.
  • The Goldman formula essentially expresses the membrane potential as an average of the reversal potentials for the individual ion types, weighted by permeability.
  • Consequently, the resting potential is usually close to the potassium reversal potential.

• Electric Potential Due to a Point Charge

  • The electric potential of a point charge Q is given by $V=\frac{kQ}{r}$.
  • Recall that the electric potential is defined as the electric potential energy per unit charge
  • The electric potential tells you how much potential energy a single point charge at a given location will have.
  • The potential at infinity is chosen to be zero.
  • Earth's potential is taken to be zero as a reference.