Chapter 3: EQ+resting pontetial

Equilibrium potentail

The electrical charge across a cell so that the chemical and electrical forces of an ion would balance out

• Each ion’s unequal distribution across the neuronal membrane = EPs

• Add up all the EPs = resting potential

Potassium and RP link

Potassium is the only ion that is permeable to the membrane; it has a huge impact on the resting potential

Voltage

measrues the stored/potential electrical energy

Potential/potential difference

same thing as voltage; the amount of energy needed to move an ion from one point to another

current

a measure of the rate of flow of electrical energy; the movement of ions

negative pontential

there is more negative chrage than postive charge

positive potential

there is more positve charge than negative charge

Ions that affect resting potential

• Potassium (K+)

• Sodium (Na+)

• Protiens

• Chloride (Cl-)

• Calcium (Ca++)

potassium and resting potential

• potasium is only permiable substance, has the largest impact

• Negativly charged protiens in a nueron attract postassium

Sodium and resting potential

• impermeable to the membrane

• can get in via sodium channels/pumps

proteins and resting potential

Intracellular space filled with proteins

• hold a negative charge, hence why the neuron is negatively charged

Chloride and resting potential

membrane is partially permeable; smaller component

• negatively charged

Clacium and resting potential

membrane is partially permeable; smaller component

• positively charged

Nueron resting potential

-65mV

resting potential factors

1. selective membrane permeability of K

2. concentration gradient for K

3. electrical gradient

4. sodium-potassium pump

what does it mean when the concentration and electrical gradient are balanced?

The neuron had reached equilibrium, and there is no movement of ions in/out of the neuron

Sodium-potassium pump

specialized channel that maintains gradients

• for every 2 K in, 3Na out

• hyperpolarizes the neuron

Hyperpolarization

Increasing the difference between the charges

• the cell becomes MORE negative

• Ex. Sodium-potassium pump kicks out more positive charges than it brings in, lowering the overall cell charge

depolarization

decreasing the polarization towards zero

• cells become MORE positive

Excitation threshold

An electrical level above which ANY stimulation results in mass depolarization;

• Precursor to the action potential

• Occurs after enough depolarization has occured