Cell membrane potential
Electrical potential
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You know cell structure
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You know cell communication
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You know cell membrane controls passage and
uses energy to pump solutes against a gradient
The Membran and the cells pumping is what
creates a different environment inside and
outside and hence the cell membrane potential
History
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Italian Anatomist Luigi Galvani used frog legs
dissected free and put electrical currents and
observed contractions late 1700's
The membrane makes a cell “polar”
Wheras electricity in a metallic wire is conduct
of flow of electrons, in the cell it is carried out
by flow of major inorganic ions across the
mebrane such as Ca2+, K+, Na+, Cl-, HCO3-
What is it
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It is the difference in electrical potential between
the interior and exterior of a biological cell
Usually given in millivolts and typical values are
-40 - -80 mV for a cell
A way to understand this is to see the
membrane ion pumps as “batteries”
Two major functions
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This electrical charge across the membrane
and and polarity of the cell gives the cell two
major functions
It can use this electrochemical gradiant as
means to transport as we have already
discussed
In excitable cells such as muscle and neurons it
allows cells to send signals within the cells,
changing locally the membrane potentential
Resting potential
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Excitable cells have a potential around 7080mV (negative) referred to as resting potential
By opening ion gates it can induce movement
away from resting potential and this is referred
to as depolarization if resting potential becomes
less than or hyperpolarization if it becomes
higher than.
A sufficiently large depolarization can lead to an
action potential – in which the there is rapid and
significant change in potential for a short time
Action Potential
Going through the steps
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5 Resting potential
1 A stimulus is given, and a certain threshold
much be reached in order to reach an Action
Potential
2 Sodium channels are opened and a big influx
happens – depolarizing additionally and rapidly
3 Channels disabled, Potassium efflux and
rapid repolarization occurs
4 A period of hyperpolarization
Channels
Made easy
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This model is made for understanding what can
happen to cell during
depolarization/repolarization
Other ions can contribute as well
Fundamentals
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You now have fundamentals in place
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Cell structure
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Cell membrane and it's functions
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Cell communication
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We shall now apply this to different tissue and
look more up close on different muscle tissue
and nervetissue