Membrane potentials - graded potentials Flashcards
What are graded potentials?
primarily generated by sensory input, causing a change in the conductance of the membrane of the sensory receptor cell.
depolarise the cell to threshold and fire an action potential
What are examples of graded potentials?
generator potentials
postsynaptic potentials
endplate potentials
pacemaker potentials
What is a generator potential?
at sensory receptors
What is a postsynaptic potential?
at synapse
What is an endplate potentials?
at neuromuscular junction
What is a pacemaker potential?
in pacemaker tissue
Do graded potentials travel well along the axon?
no graded potential’s electrical current get smaller as they travel along the membrane
useful over short distances
Are graded potentials hpo or depolarising?
both
Ho wmany snaspes doe sone neurone have?
many
Can graded potentials summate together?
yes, can lead to an action potential
What is the red and blue arrow?
red = concentration gradient
blue = electrical gradient
What dictates the electrical gradient?
the charge of the ion
chloride wont flow into the cell because of the negatively charge ion wont flow to the negative intracellular charge.
describe this diagram
If you want to use depolarise the cell, what channel would you open?
calcium
also sodium but it effects lots of enzymes
If you want to hyperpolarise a cell, what channels would you open?
potassium
chloride
what would you do to potassium leaky channels to depolarise the cell?
close them
What are 2 ways the cell manipulates the ion channels to cause hyperpolarisation?
neurotransmitter bind to the ionotropic chloride receptor, chloride comes in and hyperpolarise
= away from AP, inhibitory
open even more potassium channels. via GPCR, metabotropic receptor
What is the Cl- receptor called?
ionotropic
What is the potassium receptor called?
metabotropic
Is the ionotropic chloride channel fats or slow?
fast
Is the metabotropic potassum chnnel fast or slow?
Slow, there is a delay
what is a monovalent cation channel?
not fussy, lets ions with a charge of one through
how does the cell depolarise post-synaptically?
neurotransmitter binds to the monovalent cation channel
- sodium moves in due to the concentration and electrical potentials
- small amount of potassium moves out (small electrical potential)
- fast
block the potassium leaky channels via GPCR
- slow
