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8/21/2019 K-37_Fungsi & Sifat Jantung
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Function of theCardiovascular system
Departemen Fisiologi
Fakultas Kedokteran
Universitas Sumatera Utara
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Functions of the Cardio-Vascular System
Delivery of O2, Glucose and other nutrients
to active tissues.
Transport of metabolites and other
substances to and from storage sites.
Transport of hormones, antibodies and other
substances to site of action.
Dr Peter K. McFawn Department of Physiology Queens University Botterell Hall 4thfloor
[email protected] http://meds.queensu.ca/physiol/underg.html
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The Circulatory System
2 main divisions
Pulmonary circulation (heart lungs)
Pulmonary artery: deoxygenated blood from the heart tothe lungs
Pulmonary vein: oxygenated blood from the lungs to the
heart
Systemic circulation: (Heart rest of the body) Aorta: feeds oxygenated (arterial)blood to the body
Venae cavae: returns deoxygenated (venou s)blood
from the body
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Histology of cardiac muscle
Two classes of cardiac muscle cells
1) Specialized muscle cells of conducting
system
2) Contractile cells
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Conducting System of the Heart
AV Node
Posterior Inferior Fascicle
Anterior Superior Fascicle
Septal Depolarization Fibers
Purkinjie Fibers
Inter- nodal Tracts
Bundle of HIS
Left Bundle
Branch
Right Bundle
Branch
SA Node
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Autorhytmic cells begin depolarizing due to a slow continuous
influx of sodium and reduced efflux of potassium
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When threshold is reached, the fast calcium channel
open, and calcium rushes in
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Reversal of membrane potential triggers opening of potassiumchannels, resulting in rapid efflux of potassium
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Diagram of the membrane potential of
pacemaker tissue.
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ELECTRICAL
PROPERTIESThe resting membrane
potential -90 mV
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Depolarization lasts about 2 ms, but plateau phase
and repolarization last 200 ms or more.
Repolarization is therefore not complete until the
contraction is half over.
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Excitation (Depolarization of plasma membrane)
Opening of voltage-sensitive plasma membrane Ca2+ channels in T tubules
Flow of Ca2+into cytosol
Ca2+binds to Ca2+receptor on the
external surface of the sarcoplasmic
reticulum
Opening Ca2+channels intrinsic
to these receptors
Flow of Ca2+
into cytosol
Cytosol Ca2+concentration
Contraction
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Relation of Tension to Length in Cardiac
Muscle
Star l ing's law of the heartor Frank-Star l ing law = "energy of contraction is
proportional to the initial length of cardiacmuscle fiber."
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Kesanggupan intrinsik jantung untuk penyesuaian
diri terhadap beban yang berbeda
Dalam batas fisiologisjantung akan
memompakan semua darah yang masuk kedalam
jantung tanpa menimbulkan penumpukan darah
berlebihan. Ini disebabkan oleh peregangan yang
ditimbulkan volume darah yang masuk menyebabkan kekuatan kontraksi bertambah.
Frank StarlingS LAW
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Kurva Frank Starling
Stro
kevo
lume
End Diastoli c Volume
STRETCHING OF MYOCARD
Total blood
volume
Body
position
Intrathoracic
pressure
Atrial
contribution to
ventr.filling
Pumping action of
skletal muscleVenous tone
Intrapericardial
pressure
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= Length of muscle fiber = preload
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Kurva Frank Starling
Stro
kevo
lume
End Diastoli c Volume
Normal
Stimulasi
Adrenergik
Fungsi jantung
Syok
Kardiogenik
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Myocardial Contractility
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Let it beat