Unit 2: Lecture 10: Neurophysiology Pt.1

RMP(Resting Membrane Potential)

intracellular

approximately -70mv

Transmembrane potential of a neuron

inside cell= more (-)

Na+ is greater outside cell

K+ is greater inside cell

Cl- is greater outside cell

Charge Differential

Ions are distributed unequally

Negatively charged proteins inside the cell membrane

Selectively permeable

Membrane Channels

Passive/Leak Channels

Chemically Regulated Channels/Ligand Channels

Mechanically Regulated Channels

Voltage Regulated Channels

Passive/Leak channels

Always open

main cause for MP

found on the dendrites, axon, and terminals

Chemically Regulated Channels/Ligand channels

Can be open or close in response to a specific chemical

NT opens the gate to allow ion movement

Mechanically Regulated Channels

Any Distortion to the cell membrane

touch, pressure, vibration, that will pull or stretch the channel

Found only on the dendrites and soma

Voltage Regulated Gated Channels

Changes in the transmembrane potential

Found on the Axon and Terminals

Electrochemical Gradient

Potential Energy maintained by plasma membrane potential

Chemical Gradient

move high to low

higher force than electrical

K+ wants to move out of the cell

Na+ wants to move into the cell

Electrical Gradients

based on charge

opposites attract

K+ wants to stay attracted to negative

Na+ wants to stay attracted to negative

Net Gradient

K+ partially in favor moving out of the cell

Na+ Strongly in favor of moving into the cell

Electrochemical Gradient: K+

RMP= -70 mv

wants to move out

become more (-)

Equillibrium = -90 mv

Electrochemical Gradient: Na+

RMP= -70mv

wants to move in

become more (+)

Equilibrium= +66 mv

Na+/K+ ATPase Pump

Maintains RMP

Return Cells to RMP after changes to the MP

Exchanges 3 Na+ for 2 K+ in the cell

Requires ATP (energy)

Moves against the concentration Gradient

Returning AP levels of ions

Step 1 of the Na+/K+ pump

3 Na+ outside MP

K+ inside

Step 2 of the Na+/K+ pump

ATP will phosphorylate the membrane pump

ADP+Pi

covalent bond PE converted to KE when broken

Step 3 of Na+/K+ Pump

3 Na+ released out of cell

Step 4 of Na+/K+ Pump

2 K+ binds to inside of MP

Step 5 of Na+/K+ Pump

Phosphate detaches from MP

Closes the MP

Step 6 of Na+/K+ Pump

Releases K+ into the cell