Lecture 11: Neuronal Signalling Flashcards
in muscle cells, which voltage causes cell contraction and relaxation
+20 mV causes contraction
-90mV causes relaxation
what does a fully permeable membrane have a Vm of and what does it result in
0 mV, results in cell death
in what direction does sodium move when a sodium channel opens
- into the cell, giving it a positive potential
- tend to activate cells
in what direction does potassium move when a potassium channel opens
- out of the cell, giving it a negative potential
- activate cells and stop activity
at what Vm do sodium channels open
> -50 mV
what is sodium’s equilibrium potential
+60 mV
what is potassium’s equilibrium potential
-90 mV
what is calcium’s equilibrium potential
+123 mV
what is chlorine’s equilibrium potential
-40 mV
what is a typical neuron’s resting potential
-70 mV
what is the potential of a membrane during an action potential
+40 mV
what are the stages in an action potential
1) depolarisation, causing sodium channels to open after a stimulates exceeds threshold voltage
2) action potential
3) sodium channels inactivated and delayed potassium channels open to cause repolarisation
4) refractory period with hyperpolarisation, during which new action potentials can’t be initiated
what is the synaptic bouton
where the neurotransmitter is released
what triggers synaptic transmission
increased calcium levels allow vesicles to fuse with the membrane and expel neurotransmitter into synaptic cleft
what is a neurotransmitter
an endogenous signalling molecule released extracellularly by a neuron under physiological conditions
