Lecture 6 - Resting membrane potential part 1 Flashcards
How do neurones transmit information?
• The nervous system captures, transforms and transmits information.
• The ability to transmit an electric signal is a defining feature of neurons.
The action potential is a very rapid (2 ms) of the resting membrane potential.
what’s a defining feature of neruones?
The ability to transmit an electric signal is a defining feature of neurones.
what are some key components to resting membrane potential?
- charged atoms/molecules that are dissolved in the intra- and extracellular fluid.
- neuronal memrbane
- proteins
- forces
How is an action potential generated?
Movement of ions with different electric charges across the membrane through specialised proteins
is water a polar molecule?
yes
what an ion?
atoms with a net electric charge + or -
whats a positive ion called?
cation
whats a negative ion called?
anion
ho w is a sphere of hydration formed?
Water molecule stick electrostatically to ions
what ions are dissolved in the brain?
calcium, sodium, potassium and chloride.
The cell membrane is self ______.
organising
the polar heads are?
hydrophilic
the lipid tail is?
hydrophobic
what are ion channels made from?
multiple subunits (protein in tertiary structure)
what are the two states of a neurone?
resting and action
what does a neurone do at resting state?
A neuron is integrating incoming signals and is not generating an action potential
what does a neurone do in action state?
A neuron has been excited past threshold and fires an action potential.
what is membrane potential?
the voltage across the membrane at any moment
membrane potential is represented by?
Voltage in millivolts (Vm)
at rest what is the voltage?
-65
The inside of a cell is more _______ relative to the outside.
negative
Resting membrane potential is determined by which two forces?
- Concentration (diffusion)
- Electrostatic pressure (voltage)
what does voltage do to ions?
pushes and pulls them around
Ions have an electric charge and moved by _____ ______.
electrostatic
pressure
define current?
movement of electric charge
whats the current conductance and voltage equation? (ohms law)
I = gV
what happens when voltage and diffusion interact?
- membrane impermeable to K+ and A-
- big concentration gradient
- no electrical gradient
- charged particles trapped inside in equal amounts
- No potential difference between inside and outside of cell
How is a balance met?
- diffusion of K+ down concentration gradient
- cell becomes more negative
- electric potential difference pulls K+ back in
- equilibrium reached, no net K+ leaves
what happens to forces at equilibrium?
they are equal and opposite
what happens to potassium during equilibrium?
No net movement of potassium
still a lot of potassium inside
what is equilibrium potential?
- The electrical potential difference that exactly balances an ionic concentration gradient, if the membrane were permeable only to that ion.
what are Large changes in membrane potential caused by?
minuscule changes in ionic concentrations
The net difference in electric charge occurs at the ____ and ____ surfaces of the membrane.
inside
outside
whats the equilibrium potential for potassium?
-80mV
whats the ion driving force?
EK = –80 mV; Vm = –65 mV; difference = 15 mV
ENa = 62 mV; Vm = –65 mV; difference = –127 mV
whats the equilibrium potential for sodium?
62mV
If the concentration difference across the membrane is known for an ion, what can be calculated for that ion?
equilibrium potential
what is the Nernst equation?
(RT/zF)
If you know what the _________ of an ion is inside and outside of a neuron, you can use the _____ equation to calculate the equilibrium potential for that ion
- concentration
2. Nernst
