Nerves 3 Flashcards
what is the “magic treshold”?
-55mV
what makes a cell depolarise to -55mV? (become more positive from RMP)
external stimuli acting on specific ion channels to create a graded potential where size of potential is related to size of stimulus
where do graded potentials occur in neruones?
in terminals of the sensory neurones (in response to stimuli)
when does the graded potential become an action potential?
when GP becomes big enough and reaches treshold
where does AP release neurotransmitter molecules which activate pharmacological receptors on the second cell?
at the synapse (junction between two neurones)
what is an endplate potential?
- Graded potential; occurs at neuromuscular junction as the motor neurone depolarises the muscle to treshold by evoking a GP.
- on post-synaptic cell, occurs in skeletal muscle
what is the main job of a GP?
get the cell up to treshold (decides if AP should be fired and when)
what is signal transduction?
when a physical stimulus is turned into an electrical impulse
where are generator potentials made? (example of a GP)
in SENSORY receptors
when is the electrical impulse passed from cell to the next cell?
when it reaches treshold (if action potential that is fired, depolarises the cell and makes it reach minimum treshold)
what are 4 examples of graded potentials? (GPEP)
- generator potentials (at sensory receptors)
- Postsynaptic potentials (at synapses)
- endplate potentials (at neuromuscular junction)
- pacemaker potential (in pacemaker tissues)
what are the 4 properties of graded potentials? (ENDL)
- electrotonic potentials
- decremental potentials
- non-propagated potential
- local potential
If Na/K pump is poisoned, what will happen to the cell membrane potential?
little immediate effect
what does decremental mean?
gradual decrease in GP
what distances does GP travel in?
short distances
