this PPT is prepared after reviewing several standardized textbook of physiology and anatomy. in this PPT physiological anatomy is described in detail and easy language. It includes several relevant well labeled diagrams for better understanding of the topic.
2. THE HEART
• The human heart weighs approximately 300gms
• It contains four chambers:
• Two thin walled atria separated by an interatrial septum
• Two thick walled ventricles separated by an interventricular septum
• Atria :
1. RA receives blood from the systemic circulation via superior and inferior
vena cavae
2. LA receives blood from the lungs via pulmonary artery
• Ventricles :
1. RV supplies lung circuit via pulmonary artery
2. LV supplies the systemic circuit via aorta
*A.K Jain 4th EDITION
5. PHYSIOLOGICAL HYPERTROPHY OF LV
• Systemic arteries offer greater resistance to blood flow LV has to do larger amount
of work compared to RV
• Thickness of LV wall is more than RV wall (3:1 respectively)
*A.K Jain 4th EDITION
6. THREE LAYERS OF THE HEART
• ENDOCARDIUM : The cavities of cardiac chambers are lined by endothelial lining
called as endocardium.
• MYOCARDIUM : The muscles of the heart including the pace making and
conducting system structures are called, myocardium.
• PERICARDIUM : The entire heart is enclosed by a double layered structure, called
myocardium.
• The cavity between its two layers is filled with pericardial fluid (5-30ml clear fluid)
• Pericardial fluid lubricates the heart
• Permits heart to contract with minimal friction
• Protects the heart from external injury
*A.K Jain 4th EDITION
7. VALVES IN THE HEART
• Atrio-ventricular Valves (A-V Valves)
• Atria and ventricles are connected by a fibrous A-V ring, on the right side by the
Tricuspid valve, and the left side by Mitral valve
• These AV valves:
• Prevent backward flow of blood from ventricles to atria during ventricular systole
• Close and open passively with pressure gradient forces
• AV valves consists of flaps attached at the periphery of the valve ring
• Chordae tendinae, originate from papillary muscles arising from the inner border of
the ventricle, are attached to the free edges to the valve flaps
• Papillary muscles prevent the bulging of valve into the atria during ventricular
contraction and contract when the ventricular walls contract
*A.K Jain 4th EDITION
8. CONT…
• Semilunar valves :
Consists of three flaps of half moon shape and are of two types :-
• Pulmonary valve : situated at pulmonary orifice which leads from the RV to the
pulmonary artery
• Aortic valve : situated at aortic orifice which leads from the LV to the aorta
• These valves also open and close with passive gradient forces
*Ross and Wilson
11th edition
9. HEART SOUNDS
• Closure of AV valves causes the first heart sound and marks the onset of ventricular
systole
• Best heard over mitral and tricuspid areas
• Coincides with the R wave of ECG
• Closure of Semilunar valves causes the second heart sound and marks the onset of
ventricular diastole
• Best heard over pulmonary and aortic areas
• Coincides with the end of T wave of ECG
*A.K Jain 4th EDITION
10. PACEMAKER TISSUE OF THE HEART
• Tissues concerned with the initiation and conduction of the heart beat , are called
pacemaker tissues
• They include:
• SAN
• AVN
• Bundle of His
• Purkinje fibres
Property SAN AVN
LOCATION Posteriorly at the junction of SVC with RA Posteriorly on the right side of the
interatrial septum
STRUCTURE Ill defined cell outline, rich in glycogen and mitochondria .
These fibres can generate and discharge impulses more
rapidly than any other pacemaker and their rate of
discharge determines the rate of heart beat.
Same as that of SAN
INNERVATION By right vagus nerve, also receives sympathetic nerve fibres By left vagus nerve, also receives
sympathetic nerve supply primarily
from left side
*A.K Jain 4th EDITION
11. CONT…
The bundle of His :
• Originates from AVN then dives into right and left branch
• The left branch divides into an anterior and posterior fascicle
• The right branch passes down the right side of the interventricular septum
• Both branches divide repeatedly to form a network of fibres in the ventricles
Purkinje Fibres :
• Originates from terminal divisions of right and left branch of the bundle of His to
penetrate the ventricular wall
• Are thicker and larger than cardiac muscle fibres and thus transmits the impulse at
fast velocity of 4mts/sec as compared to others
• Allows immediate transmission of impulses throughout the entire system
*A.K Jain 4th EDITION
12. Serial
no.
Cardiac tissue Conduction speed
1. Sino Atrial Node 0.05 mtr/sec
2. Atrial pathways 1.0 mtr/sec
3. Atrio Ventricular Node 0.05 mtr/sec
4. Bundle of His 1.0 mtr/sec
5. Purkinje System 4.0 mtr/sec
6. Ventricular Muscles 1.0 mtr/sec
7. Atrial Muscles 1.0 mtr/sec
*A.K Jain 4th EDITION
