Lecture 3 - Cellular neurophysiology Flashcards
Na+ is concentrated on the ….. and K+ on the …..
outside, inside
what pumps Na+ out of the cell and K+ in?
Na+/K+ ATPase pump
which channels do K+ leave the cell via?
potassium leak channels
what is the chemical gradient?
concentration difference between inside and outside of cell
what is the electrical gradient?
ionic charge difference across the cell membrane
how many Na+ are switched for how many K+ to increase the negative charge on the inside?
3 sodium for 2 potassium
what does the nernst equation give?
the equilibrium potential of an ion present on both sides of a membrane
name the equilibrium potentials of sodium potassium and chlorine in mV
potassium = -80mV
sodium = +60mV
chlorine = -65 mV
what does the goldmann equation give?
summation of all the ion potentials to calculate resting membrane potential (-70mV)
what do Z, F, T, R and E stand for in the nernst equation?
Z = ion charge/valency
F = faraday constant
T = absolute temp
R = gas constant
E = equilibrium potential
what happens to the voltage gated sodium channels when the membrane potential reaches -55mv?
they open rapidly, sodium rushes into the cell causing further depolarization
which state does the voltage gated sodium channel return to when sodium is pumped out of the cell causing repolarization?
closed state
with voltage gated sodium channels:
open to inactivated = time…… (fast)
inactivated to closes = time …… (slow)
dependent
what happens to the voltage gated postassium channels when the membrane potential reaches - 55mV?
they open slowly, K+ moves out of the cell causing repolarisation
during hyperpolarization what happens to the voltage gated postassium channels?
opens slowly, K+ moves out of the cell and then the channels close slowly
where do action potentials start in the neuron where there are many voltage gated sodium channels?
at the axon hillock
the speed of movement of action potentials is dependent on which 2 things?
axon diameter and membrane resistance (myelination)
multiple sclerosis occurs as a result of what structure on neurons being damaged?
myelin sheath
name the 5 types of neurotransmitters
amino acids, amines, peptides, ATP and nitric oxide
give 2 examples of amino acid neurotransmitters
glutamate and GABA
give 3 examples of amine neurotransmitters
dopamine, noradrenaline, serotonin
give 3 examples of peptide neurotransmitters
CRH, opiods, substance P
what is the name of the proteins which mediate the fusion of vesicles to the PM during neurotransmission? which ion promotes the release of vesicles?
SNARE proteins, Ca2+
what are the 2 major classes of neurotransmitter receptor?
ionotropic, metabotropic
