Lecture 6: Ion Channel Intro

At resting potential, what is the cell overly permeable to and how does that effect the cells membrane potential?

The cell is overwhelmingly permeable to K+ which means the membrane potential is very close to K+ equilibrium potential

When an action potential occurs, how does the cell membranes permeability change?

The cells membrane becomes permeable to Na+, thus the mebrane potential becomes closer to Na+’s equilibrium potential

How does permeability of ions change over time?

Ion channels specific to that ion species open and close given different conditions

What are the four types of ion channels?

1. Leakage channels
2. Voltage-gated ion channels
3. Ligand-gated ion channels
4. Stretch-gated ion channels

When are leakage channels open?

All the time

When are leakage channels most influential on membrane potential?

During the rest period because they allow K+ ions to leak out, making the cell more negative

What ion is the cell membrane impermeable to during rest

Sodium (Na+)

Voltage-gated ion channels

Ion channels that are normally closed, but open in response to depolarization or hyper-polarization of the cell membrane

When do voltage-gated Na+ channels open and what does that lead to?

They open at the threshold potential which leads to an action potential

What happens to the voltage gated K+ channels after the Na+ voltage gated channels open?

Voltage gated K+ channels open, bringing the membrane potential close to the K+ equilibrium potential

Ligand-gated ion channels

Normally closed, but open when a ligand, or a very specific chemical, binds to the channel (like a neurotransmitter or a drug)

Which ion channel helps info be carried from one neuron to the next?

ligand-gated ion channel

How do synaptic potentials occur?

Synaptic potentials are due to current flow through ligand-gated channels

How do stretch activated channels work?

Two follicles are connected to each other. When there is a vibration, one moves, causing the connection between the two to stretch and open the channel