Lecture 21: Bioelectricity, Membrane Potential Flashcards
What was Galvani’s contribution to Bio-electricity?
- He experimented with frog legs & found that they could twitch
A cell is like a battery in that….
- The outside of the cell has positive charges, and the inside has negative charges
- The membrane separates electrically charged molecules
There are two types of ions (electrolytes):
- Cations & Anions
Most important cations:
- Sodium, Potassium, Calcium
Most important anions:
- Chloride, Bicarbonate
Bio-Electricity of neutrons mainly rely on:
- Sodium & Potassium
How do neurons control their current flow?
- Ion channels
- Closed = off, Open = on
- Allow ions to move past cell membrane (ion current)
How is the membrane potential maintained?
- Sodium Potassium Pump
- 3 x Na OUT for 2 x K+ IN
Difference between pumps and channels:
- Pumps = against gradient (energy consuming)
- Channels = down gradients
A membrane potential varies by:
- It’s size
- The time
The membrane potential changes if channels…
- Are open (and then shut)
When depolarisation occurs, ____ charges move in, and _____ channels are open.
- Positive
- Sodium
E.g -60mV
When a membrane potential is depolarised then hyperpolarized, ____ channels open, and _____ charges move out.
- Potassium
- Positive
- eg -80mV
Depolarisation is _____tory whereas hyperpolarisation is ______tory.
- Excitatory
- Inhibitory
Types of potential:
- Resting
- Local
- Threshold
- Action
