Flashcards
Membrane potentials
Flashcards do conjunto (16)
- 1What is a membrane potential?The potential difference difference between the inside and outside of the cell (measured in mV)
- 2How do you measure a membrane potential?inser a MICROELECTRODE into (<1 um) a cell filled with kcl
- 3Name the resting membrane potential ranges of... - animal cells - cardiac and skeletal muscle - nerve cells-20 - -90
- 80 - -90
- 50 - -75 - 4Note the ion concentration of sodium, potassium, chloride and other ions inside and outside the cellIntra Extra
Na+ 10mM 145mM
K+ 150mM 5mM
Cl- 8mM 110mM
A- 167mM 40mM - 5What two thing does equilibrium potential depend on?- diffusion (chemical gradient)
- electrical gradient
e.g. K+ if Vm is at -90 then = K+ eqiuilibrium potential so chem and elec forces are equal and there is no net flow od K+ - 6Write out the Nernst equation at 37oc and explain what it calculatesV = 61 log10 [ion]o
z [ion]i
z = valency v = voltage
It is used to figure out the eq. potential for an ion - 7How is the resting potential maintained?The resting membrane potential is more permeable to K+ than any other ion so the membrane potential is very close to the K+ equilibrium potential (-90)
- 8What is meant by 'rapid ion flow'?Where a gated pore opens and ions diffuse through rapidly - ALWAYS occurs down the electrochemical gradient
- 9Explain the terms depolarization and hyperpolarizationDepolarization = a decrease in the size of the membrane potential (cell becomes less negative)
Hyperpolarization = an increase in the size of the membrane potential (cell becomes more negative - 10Explain how we can change the membrane potential and name the eq pot of the four main ions?By changing the selectivity of the membrane towards a particular ion causes the mem pot to move closer towards the eq pot of that ion
K+ = -90
Na+ = +70
Cl- = -70
Ca2+ = +120 - 11Write out the GHK equationNernst equation except with permeabilities x concentrations of ions
- 12WHat are the three types of gating channels and how are they stimulated?1) ligand gating
binding of chemical ligand e.g. hormone
2) voltage gating
responds yo change in mem pot e.g. action potentials
3) mechanical gating
responds to membrane deformation - 13What kind of cells do synaptic connections occur between?nerve cell - nerve cell
nerve cell - muscle cell
nerve cell - gland cell
sensory cell - nerve cell - 14Summarise excitatory synapsesThey open ligand-gated channels that cause DEPOLARIZATION
Causes excitatory post-synaptic potential (EPSP)
Longer time (~20ms) and graded with amount of transmitter released
e.g. acetycholine, glutamate - 15Summarise inhibitory synapsesOpen ligand-gated causes HYPERPOLARIZATION
change in potential is called inhibitory post-synaptic potential (IPSP)
e.g. glycine, GABA - 16Name two other factors that can influence membrane potential1) changes in extracellular ion concentration (mostly K+)
2) electrogenic pumps e.g. NA/K - ATPase
one +ve charge is moved out this can contribute in make the mem pot a couple of mV more negattive
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- Physiology FlashCards sobre Membrane potentials, criado por Charlotte Pedley em 10-05-2018.
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- Charlotte Pedley
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