Do hormones or nerves produce faster responses?
How is the electrical signal of nerves made?
Through the three membrane potentials:
Resting membrane potential
Graded membrane potential
What is the resting membrane potential responsible for?
Keeps cells ready to respond
What is the graded potential responsible for?
Determines whether an action potential should be fired
What is the action potential responsible for?
Transmits signals over long distances
What is the voltage of the inside of a cell compared to the outside?
What is responsible for the inside of a cell being -70mV compared to the outside?
Leaky K+ channels
What is the equilbrium potential?
Membrane potential at which the elctrical gradient is exactly equal and opposite to the concentration gradient
The Nernst equation predicts the equilbrium potential, what does this look like?
What is 0K in oC?
What is the equilbrium potential for K+?
How does the blood brain barrier protect the brain from changes in ion concentration?
Cappilaries are especially tight
This is due to astrocytes and tight junctions
What are the typical concentrations of important ions in and outside a cell?
K+ greater inside
Na+ greater outside
Cl- greater outside
What is the equilbrium potential for Na+?
What is the equilbrium potential for Cl-?
The goldman equation predicts the equilbrium potential for several ions, what does this look like?
Why is the normal resting membrane potential (RMP) -70mV?
Electrogenic nature of the Na+/K+ pump (3 Na+ out and 2 K+ in)
Lrge intracellular negatively charged molecules
What does depolarising mean?
Takes the cell towards 0V
What does overshoot mean?
Polarises in the opposite direction
What does repolarise mean?
Polarise in original direction
What does hyperpolarise mean?
Greater polarisation in the same direction