The resting membrane potential (often called resting potential) describes the stable separation of charges across a neuron's cell membrane when the neuron is at rest (not receiving input).
Characterized by:
More positive charges (cations) on the outside of the membrane.
More negative charges (anions) on the inside of the membrane.
Structure
Neuron Drawing:
Soma (cell body) and axon, typically a thin process, here a thick representation for clarity.
Dendrites, normally thin, drawn large.
Key Terms
Anions: Negatively charged ions inside the membrane.
Cations: Positively charged ions outside the membrane.
Charge Separation
More cations outside and more anions inside the neuron membrane.
Voltage difference measured as the difference between inside and outside (outside set to zero).
Typical resting potential: ~-60 millivolts (mV).
Ion Concentration Gradients
Concentration differences (gradients) of ions across the cell membrane are crucial.
Key Ions:
Cations:
Potassium (K+)
Sodium (Na+)
Calcium (Ca2+)
Anions:
Chloride (Cl-)
Organic anions (e.g., proteins with net negative charge).
Ion Concentration Details
Organic Anions and Potassium (K+):
Higher concentration inside the neuron.
Sodium (Na+), Calcium (Ca2+), and Chloride (Cl-):
Higher concentration outside the neuron.
Forces Acting on Ions
Electrical Force:
Ions attracted to opposite charges across the membrane.