CARDIOVASCULAR SYSTEM Anatomy & Physiology dr. Jeffrey Wirianta March 8 th 2004
CARDIOVASCULAR SYSTEM
Anatomy & Physiology
dr. Jeffrey Wirianta March 8th 2004
THE HEART
Lokasi Jantung
Di dalam Pericardium di rongga mediastinum dalam rongga Thorak
Tepat di belakang tulang dada ( sternum )
Kurang lebih 2/3 bagian terletak di sebelah kiri dari garis tengah
Fungsi dan Ukuran
Fungsi : sebagai pompa ganda agar terjadi
aliran dalam pembuluh darah yang
disebabkan adanya pergantian antara
kontraksi ( sistolik ) dan relaksasi
( diastolik )
Ukuran : 250 – 350 gram
( kira-kira sebesar kepalan tangan )
Fibrous Skeleton
Kerangka jantung yang terdiri dari jaringan kolagen yang tebal dan kuat
Penunjang fisik jantung
Pegangan katup
Mencegah kelebihan regangan otot jantung
Electrical insulation
Anatomy of the Heart
Pericardium :
Outer fibrous sack
Myocardium :
Thick muscle walls
Endocardium :
Innermost surface
Endothelium
Simple squamous epithelium
Interventriculer Septum
Papillary muscle
Semilunar Valve
Perikardium
Perikardium Fibrosa
Lapisan paling luar rongga Pericardium
Menjaga kedudukan jantung di rongga mediastinum
Perikardium Serosa
Lapisan parietalis
Lapisan bagian dalam dari rongga pericardial
Lapisan visceralis / epicardium
Rongga Perikardium
Cairan pericardium
Mengurangi gesekan saat jantung bergerak
Anatomy of the Heart
Heart chambers :
Left & right atria
Left & right ventricles
Heart valves :
Atrioventricular valves :
Right : Tricuspid
Left : Bicuspid/Mitral
Semilunar valves
Right : Pulmonary valve
Left : Aortic valve
Anatomy of the Heart
Aorta
Coronary arteries
Arterioles
Capillaries
Venules
Coronary sinus
Right atrium
Coronary circulation
Tipe-tipe sel Otot Jantung
Autoritmik autoritmik – mampu berdepolarisasi spontan
produce pacemaker potentials
menyalurkan aksi potensial ( impulses ) melewati myocardium
tidak berkontraksi
Kontraktil Potensial aksi menimbulkan kontraksi
Aliran darah ditimbulkan oleh pergantian dari
kontraksi ( SISTOLIK ) dan Relaksasi ( DIASTOLIK )
Intrinsic Conducting System
Sinoatrial node
Electrical pace maker
Atrioventricular node
Receives impulses originating from SA node
Bundle of His
Electrical link between atria and ventricles
Purkinje fibres
Distribute impulses to ventricles
Sel Autoritmik
• Fase Depolarisasi
• Fase Repolarisasi
• Fase Istirahat
Sel Kontraktil
• Fase Depolarisasi
• Fase Plateu
• Fase Repolarisasi
• Fase Istirahat
Conduction System
SA Node Internodal branch
AV Node Hiss Bundle Purkinje Fiber Contraction
Cardiac Action Potentials
Cardiac Muscle Tissue
The Electrocardiogram ( ECG )
P wave : atrial depolarisation
QRS complex : ventricular depolarisation
T wave : ventricular repolarisation
Atrial repolarisation hidden by QRS
P
Q
R
S
T
The Electrocardiogram (ECG)
Leads can be placed on wrists and left ankle
( right ankle is earthed )
Voltages are measured across each point as shown I = L wrist to R wrist
II = R wrist to L ankle
III = L ankle and L wrist
The heart sits in the centre of the triangle
I
II III
+/-
+
-
The Electrocardiogram
The three standard measurements can be used to electronically calculate the currents flowing towards each limb
aVR
aVL
aVF
+
The Cardiac Cycle
Systole :
Period of ventricular contraction
Blood ejected from heart
Diastole :
Period of ventricular relaxation
Blood filling
Stroke Volume
The amount of blood ejected from the heart in one beat
Average is 60 - 100 ml
Depends on preload, contractile force and afterload
Cardiac Output
The amount of blood ejected from the heart in one minute
Cardiac output = heart rate x stroke volume
Starling’s Law
The more the myocardium is stretched, the greater the stroke volume
Has limits
Dependent upon venous return
Blood Pressure
BP = cardiac output x systemic vascular
resistance
Definitions
Chronotropy Change in heart rate
Inotropy Change in contractile force
Dromotropy Change in conduction velocity
Can be positive or negative