13 Questions
What is the role of voltage in an electrical circuit?
To apply force or pressure to push the charge in a closed looped conductor
According to Ohm's Law, what is the relationship between potential difference (V), current (I), and resistance (R) in a circuit?
$I = V/R$
What does current represent in an electrical circuit?
The rate of flow of electric charge
What does Ohm's Law state about the relationship between current, resistance, and potential difference in a circuit?
V = IR
If 12.0 V is applied to an automobile headlight and 250 mA flows through it, what is the resistance of the headlight?
48.0 Ω
What primarily determines the membrane potentials in cells?
The concentration of ions on the inside and outside of the cell
What will be measured if a voltmeter is used to measure voltage across the cell membrane (inside versus outside) of a cardiomyocyte?
Negative voltage inside and positive voltage outside
What is the resting membrane potential caused by?
Differences in the concentrations of ions inside and outside the cell
Which ion has a much higher concentration in the cytoplasm compared to the extracellular fluid?
K+ ions
What is the general rule regarding membrane potential?
It is a weighted sum of the equilibrium potentials of all permeant ions
What is the equilibrium potential for a given ion?
The membrane potential at which the electrical and concentration forces are balanced for a given ion
What primarily determines the membrane potentials in cells?
The concentration of ions on the inside and outside of the cell
What primarily determines the membrane potentials in cells?
The concentration of ions on the inside and outside of the cell
Study Notes
Electrical Circuits
- Voltage plays a crucial role in an electrical circuit, enabling the flow of electric current.
- According to Ohm's Law, the relationship between potential difference (V), current (I), and resistance (R) is V = I × R.
- Current represents the flow rate of electric charge in a circuit.
Resistance and Voltage
- If 12.0 V is applied to an automobile headlight and 250 mA flows through it, the resistance of the headlight is 48 ohms (calculated using Ohm's Law).
Cell Membrane Potentials
- The membrane potential in cells is primarily determined by the concentration gradient of ions across the cell membrane.
- A voltmeter measures the voltage across the cell membrane (inside versus outside) of a cardiomyocyte.
- The resting membrane potential is caused by the concentration gradient of ions, particularly potassium (K+) and sodium (Na+) ions.
- Potassium ions have a much higher concentration in the cytoplasm compared to the extracellular fluid.
- The general rule regarding membrane potential is that a higher concentration of ions inside the cell results in a more negative resting membrane potential.
- The equilibrium potential for a given ion is the potential difference at which the tendency of the ion to diffuse down its concentration gradient is balanced by the electric force driving it in the opposite direction.
- The concentration gradient of ions across the cell membrane primarily determines the membrane potentials in cells.
Test your knowledge of membrane potential and voltage in biophysics with this quiz. Explore the concepts of electrical circuit, voltage, current flow, and resistance in the context of biophysics.
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