L16 Flashcards
what causes the resting membrane potential? 2 factors
phospholipid membrane is impermeable to ions and there is an uneven distribution of ions between inside and outside of the cell
what goes in and out of the sodium-potassium pump and at what ratio?
3 Na+ out : 2 K+ in
How does the sodium-potassium pump work?
if Na+ levels are high inside the cell, the pump breaks down ATP to produce energy and drive ions against their concentration gradients
what other pump transports what out of the cell that contributes to the uneven distribution of ions across the membrane?
Ca2+ out of cell by calcium pump
what does it mean if a cell is hyperpolarised?
the membrane potential becomes more negative that it is at resting potential
what does it mean if a cell is depolarised?
the membrane potential becomes more positive than it is at resting potential
what is IPSP?
inhibitory post synaptic potential
what inhibits the neuron?
influx of negative ions (hyperpolarisation)
What excites the neuron?
influx of positive ions (depolarisation)
what two factors encode information in AP’s?
the frequency of AP’s in individual neurons and the distribution and number of neurons firing action potentials
signals do not ___ over distance; they are signals of fixed ___ and ___
diminish; size, duration
what are the 4 changes to the membrane during an action potential?
- stimulus/electrical signal moves membrane potential to threshold
- this causes VGNa+C’s to open, Na+ flows in
- Na+ channels close and VGK+C’s to open, K+ flows out until K+ equilibrium reached
- Na+/K+ pumps return membrane to resting potential
what is EPSP?
excitatory post synaptic potential
what is spatial summation?
multiple input neurons summating ESPS that are generated simultaneously at many synapses on a dendrite, if summation reaches threshold the neuron will fire an action potential
what is temporal summation?
one input neuron strongly activated, if summation reaches threshold the neuron will fire an AP
