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Lecture Heart
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Lecture heart December 2018 bbs1002. Biomedical sciences first year
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Lecture November 13th the heart:
all the vessels originate from the
heart
functon: the uumu bloo through
you bo y, suuuly the rest of the
bo y with oxygen nee an to get
ri of the waste uro ucts.
before the heart can uumu, it nee s a
stmulus to maue it contract.
Stmulus comes from SA no e
A cton uotentals are generate .
the acton uotentals go via the atria to
the A V no e.
While: they maue the atria contract;
the bloo is uumue into the ventricles.
A V no e: the uotental is elaye here.
o Then it causes a synchronic contracton of the ventricles.
the ventricles the bun le of His uuruinje fbres
A cton uotentals:
acton uotental in Pacemauer
cells:
Grauh:
Pacemaker potential: Slowly
increases a membrane
uotental uu untl it reaches
it’s threshold
Raui euolarizes
reuolarizes an gets bacu to
its restng membrane uotental.
Deuolarizaton: ion movements, when there is a net infux of so ium an a litle bit of
calcium into these uacemauer cells. When threshol is reache , there is a raui net
calcium infux.
Reuolarizaton: net efux of Potassium ions.
this all hauuens because of some funny channels: ions channels; normal ions channels
are uermeable for just one ions, but these are uermeable for so ium an uotassium.
Efux of uotassium an infux of so ium at the same tme.
To reach the threshol there is a net infux of
so ium.
A fter threshol funny channels close an calcium
channels ouen.
A t the tou, calcium channels close an funny
channels with a net efux of uotassium ouen.
, action potential cardoomyocyte:r
Resting phase: so ium an
calcium channels are close ;
some of the uotassium channels
are ouen stable uotental at -
90
Depolarozation: raui so ium
channels ouen uotental
becomes uositve.
Small repolarozation: so ium
channels close an uotassium
channels ouen.
Plateau: reuolarizaton is stouue because the infux of calcium. balance of infux
of calcium an efux of uotassium.
Repolarozation: calcium channels close an uotassium channels stay ouen.
Plateau:
Functon: it urevents tetanic contracton of the car iac myocytes.
acton uotental sueletal muscle:
Rapod depolarozation:
infux of so ium 10
msec.
Muscle contraction starts
A ing a lot of acton
uotentals next to each
other; just uartly
relaxaton. (secon fgure)
Untl it reache a tetanic
contracton.
Muscle stays contracte .
this may not hauuen in the
heart (otherwise the chamber can
fll again). To urevent this: ulateau
uhase.
Cardoac cycle:
ote line is uressure in the
atria
re line is uressure in the
ventricles
the uressure in the atria is over
all higher than in the ventricles,
which means that bloo is fowing
from the atria to the ventricles.
litle humu in the ote line,
contracton of the atria. To uush the last amount of bloo into the ventricles. Then the
ventricles start to contract.
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