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Lecture Heart

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Lecture heart December 2018 bbs1002. Biomedical sciences first year

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  • January 12, 2019
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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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