Sept 12 th
• If you were to make the cell only permeable to potassium then the cells membrane
potential would be equal to its equilibrium potential. It’s the membrane potential of the
cell under the concept that the cell is only permeable to one ion.
• Electrical impulses that travel to the brain are action potentials
- anesthesia can block these electrical stimulation to brain
• Receptor potential: graded (strength depends on stimulus). Causes an action potential.
When stimulus occurs (something touches finger) then ion channels open, and sodium
rushes in depolarizing the cell and causing an action potential
• Synaptic potential: transfer of info from one neuron to another. Occurs between axon of
presynaptic neuron and dendrites of posysynaptic neuron
• Action potential moves up and down as a function of time. “always detecting past” since
it’s takes time for brain to perceive stimuli
• Sodium ions go in cell first from sensory receptor or synaptic activity (finger touching
something) which opens gate (gating charge is positive and in repelled by sodium in
• Inactivation gate and open gate. 3 states: closed, open and inactivated.
• Potassium leaves cell via voltage gated K+ channels. Follows electrochemical gradient
and concentration gradient causing cell to become more negative