BASIC INTRODUCTION OF ANATOMY OF HEART
• 4 Chambers
– 2 Atria - upper
– 2 Ventricles- lower
•
-
Valves
Tricaspid valve
Bicaspid valve
Semilunar valve
• Conducting system
• Pacemaker
-
S.A node
Internodal fibers
A.V node
Bundle of his
Bundle branch
Purkinje fibers
CARDIAC CYCLE
• Cardiac cycle is the proper occurring of events as
blood enters the atria, leaves the ventricles and
then starts again.
• Phases of cardiac cycle
• Phase of the cardiac cycle when myocardium is
relaxed is termed DIASTOLE.
• Phase of the cardiac cycle when the myocardium
contracts is termed SYSTOLE.
• Alternating periods of systole and diastole occur in cardiac cycle.
• Phases of the cardiac cycle.
1. Atrial systole.
2. Ventricular systole.
3. Diastole of the whole heart. REST
Atrial and ventricular systoles do not occur at the same time, but their
diastoles occur at the same time during the diastole of the whole
heart.
STAGES OF CARDIAC CYCLE
ATRIAL SYSTOLE…. Contraction of atrium
VENTRICULAR SYSTOLE…. Contraction of ventricles
- Isometric (isovolumetric) contraction phase
- Rapid ejection phase
- Slow ejection phase
DIASTOLE OF THE WHOLE HEART…. Relaxation of whole
heart
- Protodiastole
- Isometric (isovolumetric) relaxation phase
- Rapid filling phase
- Slow filling phase
1. Ventricular Filling Period [ventricular diastole, atrial
systole]
2. Isovolumetric Contraction Period [ventricular systole]
3. Ventricular Ejection Period [ventricular systole]
4. Isovolumetric Relaxation Period [ventricular diastole,
atrial diastole]
1. Rest
• Both atria and ventricles in relaxation…………. Diastole.
• Blood is filling both atria and ventricles due to low pressure
conditions.
2. Atrial Systole
• Atria contract.
• Ventricular get filled with blood which comes from atria.
3. Isovolumetric Ventricular Contraction
• A stage just before complete contraction of ventricles.
• Increased pressure in the ventricles causes the AV valves to
close.
» CREATES THE FIRST HEART SOUND (LUB)
• Atria go back to diastole.
• No blood flow as still semilunar valves are closed.
4. Ventricular Ejection
• Intraventricular pressure overcomes aortic pressure
– Semilunar valves open
– Blood is ejected …WHICH IS PURE OXYGENATED BLOOD
5. Isovolumetric Ventricular Relaxation
• Intraventricular pressure drops below aortic pressure
– Semilunar valves close
» SECOND HEART SOUND (DUP)
• Pressure still hasn’t dropped enough to open AV valves so
volume remains same (isovolumetric)
THIS IS THE PERIOD WHEN BOTH VENTRICLE AND ATRIA ARE IN
DIASTOLE, ATRIAL & VENTRICULAR DIASTOLE OCCUR SAMETIME
CARDIAC OUTPUT
Pulmonary Artery Blood
CARDIAC OUTPUT
VENOUS RETURN
PERIPHERAL
BLOOD FLOW
CARDIAC OUTPUT
• Cardiac Output (CO) is the blood volume pumped by the left
ventricle each minute into the aorta.
• Normal value = 5-6 liters/ minute
• Cardiac output is calculated as follows:
• CARDIAC OUTPUT = STROKE VOLUME X HEART RATE
Stroke volume is the volume of blood pumped by each
ventricle per beat; normally it is about 70 ml/ beat.
Heart rate is the number of heart beats per minute;
normally it is about 72 beat/ minute.
SO CARDIAC OUTPUT = (70ml X 72beat) per minute.
STROKE VOLUME
• End systolic volume (ESV)
• End diastolic volume (EDV)
During diastole of the ventricles, filling of the ventricles
with blood normally increases the volume of each
ventricle to about 120-130 ml.
The volume of blood present in each ventricle at the end
of ventricular diastole is called END-DIASTOLIC VOLUME
(EDV) and it is about 120-130 ml.
• During ventricular systole, as the ventricles empty, the
volume decreases about 70-80 ml out of 120-130ml
which is pumped out called Stroke volume as it is about
70 ml/ beat.
• So at the end of ventricular systole, the remaining
volume of blood in each ventricle is about 50-60 ml.
• The volume of blood present in each ventricle at the end
of ventricular systole is called END-SYSTOLIC VOLUME
(ESV) and it is about 50-60 ml.
• (120-130) – (50-60) = 70-80
• So the volume of blood ejection by each ventricle during
each ventricular systole is called stroke volume= 70-80ml
STROKE VOLUME
SV = (EDV— ESV) both volumes within the heart
1. EDV = After complete filling
2. ESV = After stroke volume remaining blood
inside chamber.
(70-80ml) = (120-130 ml) – (50-60ml)
So
EDV= ESV+ SV
(120-130 ml) = (50-60ml) + (70-80ml)
The output of both ventricles is equal, so the output of the
right ventricle goes into the pulmonary circulation equals
the output of the left ventricle into the systemic circulation.