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