Resting Membrane Potential

What is every neuron enclosed by?

plasma membrane

What is the membrane made out of?

lipid bilayer (2 layers of fat molecules)

What is the purpose of the cell membrane?

a barrier to prevent ions from freely crossing on their own

What does the cell membrane separation make possible?

electrical signaling

Inside the cell

interacellular

outside the cell

extracellular

What aqueous fluid is in the intracellular space?

cytoplasm

What aqueous fluid is in the extracellular space?

extracellular fluid

What do aqueous fluids contain?

ions

What keeps the 2 different aqueous fluids seperate?

cell membrane

What are the key ions in neurons? Name, sign

sodium Na+, Potassium K+, Chloride Cl-, Calcium Ca2+

Ionic distribution for Na+

High outside, low inside

Ionic distribution for K+

high inside, low outside

Ionic distribution for Cl-

high outside, low inside

Ionic distribution for Ca 2+

very high outside, very low inside

What is voltage

the difference in electrical charge between 2 points, a measure of stored electrical energy

What is a membrane potential?

the difference of voltage between inside and outside the cell

What is the resting membrane potential?

-70 mV

Can ions cross the membrane freely?

No, they need ion channels to pass

What are the three types of ion channels?

Leak, Ligand gated, voltage gated

Do channels let one type of ion or multiple types of ions pass?

one type of ion

Which ion channel is most relavant for resting membrane potential?

leak channels

What state are leak channels in?

always open, allowing ions to move continuously

Which ion are the leak channel’s favorite?

Potassium

What state are Ligand-gated channels in

Closed until a chemical bind

What channel opens in response to neurotransmitters?

Ligand-Gated Channels

Do Ligand-Gated channels let any ion pass, or specific ions? Which ones?

Specific Ions, Na+ and Cl-

Where are Ligand Gated Channels important at?

Synapses

What state are Voltage-gated channels in at rest?

Closed

What needs to happen for a voltage gated channel to open?

membrane needs to reach a specific voltage

What channel lets action potentials occur?

voltage gated channels

Membrane Permeability

how easy a particular ion can cross the membrane, depends on how many open channels

What ion is the membrane most permeable to?

Potassium

What are the two forces on an ion?

chemical force: concentration gradient

electrical force: membrane potential

What is a concentration gradient?

The difference in the concentration of a substance across a distance or a membrane

What is an electrical gradient

he difference in electrical charge across the membrane

Ions across a cell membrane are driven by which two independent forces?

chemical force: concentration gradient 
electrcial force: membrane potential

How do electrical forces of ions dictate ion movement based on charges?

• Opposite charges attract.

• Like charges repel.

If the inside of a cell is negative, what happens to positive ions (like K⁺)?

they rush in to the cell

What is equilibrium?

the point where the chemical force and the electrical force are equal and opposite

At equilibrium what movement of ions are there.

There is no net movement of the ion with the two pushes cancel out

Equilibrium of Na+

+60mV

Equilibrium of K+

-90mV

Equilibrium of Cl-

-70mV

Resting Potential Voltage

-70 mV

What maintains the gradients

The sodium potassium pump

What is the Sodium-Potassium Pump

Energy from ATP to actively transport ions against their concentration gradients.

Ratio of Sodium Potassium Pump

3 sodium out and 2 potassium in