The document discusses the anatomy and physiology of the heart and cardiac cycle. It describes the heart as having four chambers that pump blood through two circulations - pulmonary and systemic. The cardiac cycle involves electrical and mechanical events in the atria and ventricles over one heartbeat, including atrial systole, ventricular systole and diastole. Key phases and timing are explained. Heart sounds are produced by valve openings and closings.

1. Anatomy of Heart and
Physiology of Cardiac Cycle
By
K L V Simhachalam

2. Cardiovascular System
 Network of organs and elastic tubes
through which blood flows carrying
oxygen and nutrients to all parts of the
body
 Includes: The Heart & Blood vessels
Text book of Human Anatomy (7th Edition) by BD Chaurasia

3. Cardiovascular System
 Has two parts:
 The Pulmonary
Circulation: transports
deoxygenated blood
between the heart and
lungs
 The Systemic Circulation:
transports oxygenated blood
away from the heart to tissues
and cells, and returns
deoxygenated blood back to
the heart
Text book of Medical Physiology (2nd SEA edition) by Guyton & Hall

4. The Heart
 In the mediastinum between the
lungs
 On the superior surface of
diaphragm
 ⅔’s of it lies to the left of the
midsternal line
 Anterior to the vertebral column,
posterior to the sternum
 It is approximately the size of your
fist weighing around 250-300
grams covered in the pericardium.
Text book of Human Anatomy (7th Edition)
by BD Chaurasia

5. The Heart
 Made up of cardiac muscle fibers
 Average heart rate is 60-100 bpm,
pumping 8,000 liters each day.
 Each time the cardiac muscle
contracts, blood is pushed
through the body within blood
vessels
Text book of Medical Physiology (2nd SEA edition) by Guyton & Hall

6. Anatomy of Heart
Text book of Human Anatomy (7th Edition) by BD Chaurasia

7. Anatomy of Heart
 Shape and Size
 Chambers and Circulation
 Membranes, Surface features and Layers
 Internal Structure of Heart

8. Anatomy of Heart
 Chambers of Heart:
 Four Chambers – 2 atria and 2
ventricles
 The ventricles serve as the
primary pumping chambers
of the heart, propelling blood
to the lungs or to the rest of
the body.
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4eee-ab6e-
3ef2482e3e22@8.25.

9. Anatomy of Heart
 Membranes, Surface features and Layers
 The membrane that directly surrounds the heart is called
the pericardium or pericardial sac (double layered).
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4eee-
ab6e-3ef2482e3e22@8.25.

10. Anatomy of Heart
 Surface features of heart
 There is a superficial leaf-like extension of the
atria near the superior surface of the heart, one
on each side, called an auricle.
 Fat-filled grooves - sulcus (plural = sulci), along
the superior surfaces of the heart
 The deep coronary sulcus is located between
the atria and ventricles.
 Anterior interventricular sulcus & Posterior
interventricular sulcus
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4e
ab6e-3ef2482e3e22@8.25.

11. Anatomy of Heart
 Layers of heart
 Three layers
 Epicardium, myocardium, and
endocardium (superficial to deep)
 Myocardium is thickest
 Endocardium lines the blood
vessels
This swirling pattern of cardiac muscle tis
contributes to heart’s ability to pump bloo
effectively.
https://courses.lumenlearning.com/s
uny-ap2/chapter/heart-anatomy/

12. Anatomy of Heart
 Internal structure of heart
 Septa of heart – Atrio ventricular
& Interventricular
 Chambers – Atria and Ventricles
 Valves
 Coronary circulation
https://courses.lumenlearning.com/suny-ap2/chapter/heart-anatomy/

13. Anatomy of Heart
 Right Atrium
 serves as the receiving chamber for
blood returning to the heart from the
systemic circulation
 two major systemic veins, Superior and
Inferior venae cavae, the large coronary
vein called the coronary sinus that
drains the heart myocardium empty into
the right atrium.
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4eee-
3ef2482e3e22@8.25.

14. Anatomy of Heart
 Right Ventricle
 receives blood from the right atrium
through the tricuspid valve
 When contracts, ejects blood into
the pulmonary trunk, which
branches into the left and right
pulmonary arteries that carry it to
each lung.
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4e
ab6e-3ef2482e3e22@8.25.

15. Anatomy of Heart
 Left atrium
 After exchange of gases in the
pulmonary capillaries, blood returns
to the left atrium high in oxygen via
one of the four pulmonary veins.
 The opening between the left atrium
and ventricle is guarded by the
mitral valve.
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4e
ab6e-3ef2482e3e22@8.25.

16. Anatomy of Heart
 Left Ventricle
 Major pumping chamber for the
systemic circuit;
 It ejects blood into the aorta through
the aortic semilunar valve.
Anatomy & Physiology. Quoted from: http://cnx.org/contents/14fb4ad7-39a1-4ee
ab6e-3ef2482e3e22@8.25.

17. Anatomy of Heart
 Heart Valves
 Right Atrioventricular / Tricuspid valve
 Pulmonary valve (Right semilunar)
 Left Atrioventricular / Bicuspid / Mitral
valve
 Aortic valve
Anatomy & Physiology. Quoted
from: http://cnx.org/contents/14fb4ad7-39a1-
4eee-ab6e-3ef2482e3e22@8.25.

18. Anatomy of Heart
 Coronary Circulation
 Coronary Arteries
 supply blood to the
myocardium and other
components of the heart.
 Coronary Veins
Anatomy & Physiology. Quoted
from: http://cnx.org/contents/14fb4ad7-39a1-4eee-
ab6e-3ef2482e3e22@8.25.

19. Cardiac Cycle
 = Both electrical & mechanical events from beginning of
one heart beat to beginning of next.
 Heart is a pump in a series:
 Systole
 Diastole
Text book of Medical Physiology (2nd SEA edition) by Guyton & Hall

20. Cardiac Cycle
 Duration:
Considering normal heart rate as 75 beats /min (average),
Duration of one (1) heart beat = 60/75 = 0.8 sec.
https://byjus.com/biology/regulation-of-cardiac-activity/

21. Cardiac Cycle
 Phases:
 Atrial cycle (0.8s)
 Atrial systole (0.1s)
 Atrial diastole (0.7s)
 Ventricular cycle (0.8s)
 Ventricular systole (0.3s)
 Ventricular diastole. (0.5s)
Essentials of Medical physiology (8th edition) by K Sembulingam

22. Cardiac Cycle
Atrial cycle (0.8s)
 Atrial systole (0.1s):
 Coincide with last rapid filling
phase of ventricles.
 Before the valves are open,
ventricles relax with already
75% blood
 Contraction add only
remaining 25% blood.
Essentials of Medical physiology (8th edition) by K Sembulingam

23. Cardiac Cycle
Atrial cycle (0.8s)
 Atrial diastole (0.7s):
 Coincide with ventricular
Systole & most of the
ventricular diastole.
 Atria Relax – gradual
filling of atria – pressure
slowly increases.
Essentials of Medical physiology (8th edition) by K Sembulingam

24. Cardiac Cycle
Ventricular cycle (0.8s)
 Ventricular systole (0.3s):
 Phase of Isovolumic (Iso-metric)
Contraction (0.05s)
 Phase of ventricular ejection (0.25s):
1.Rapid phase
2.Slow phase
Essentials of Medical physiology (8th edition) by K Sembulingam

25. Cardiac Cycle
Ventricular cycle (0.8s)
 Ventricular diastole (0.5s):
 Protodiastole
 Isovolumic or Isometric Relaxation
phase.
 Rapid passive filling phase.
 Reduced filling & Diastosis
 Last rapid filling phase.
Essentials of Medical physiology (8th edition) by K Sembulingam

26. Cardiac Cycle
Events during Cardiac cylce
 Pressure changes - in atria, ventricles,
aorta and pulmonary artery
 Volume changes – in ventricles
Essentials of Medical physiology (8th edition) by K Sembulingam

27. Cardiac Cycle
Valvular events (Heart sounds)
 First Heart Sound
 Second Heart Sound
 Third Heart Sound
 Fourth Heart Sound
Essentials of Medical physiology (8th edition) by K Sembulingam

28. Cardiac Cycle
Valvular events (Heart sounds)
 First Heart Sound
• Cause – closure of A-V valves.
• Characteristics – ‘LUBB’, duration -0.15 sec, freq-25-45 Hz.
• Site for auscultation – Mitral & Tricuspid area.
• Correlation with ECG – coincide with peak of R wave.
Essentials of Medical physiology (8th edition) by K Sembulingam

29. Cardiac Cycle
Valvular events (Heart sounds)
 Second Heart Sound
• Cause – closure of semilunar valves.
• Characteristics – ‘DUBB’, duration-0.12 sec, freq–50Hz.
• Site for auscultation – Aortic & Pulmonary area.
• Correlation with ECG – coincide with T wave.
Essentials of Medical physiology (8th edition) by K Sembulingam

30. Cardiac Cycle
Valvular events (Heart sounds)
Essentials of Medical physiology (8th edition) by K Sembulingam

31. Cardiac Cycle
Valvular events (Heart sounds)
 Third Heart Sound
 Cause – In rush of blood during rapid filling phase.
 Characteristics – Duration – 0.1 sec.
 Correlation with ECG – appears between T & P wave.
Essentials of Medical physiology (8th edition) by K Sembulingam

32. Cardiac Cycle
Valvular events (Heart sounds)
 Fourth Heart Sound
 Cause – last rapid filling phase.
 Characteristics – Duration 0.03 sec, freq-3 Hz.
 Correlation with ECG – appears between P wave and onset
of Q wave.
Essentials of Medical physiology (8th edition) by K Sembulingam

33. Cardiac Cycle
Cardiac Murmurs (Abnormal Heart sounds)
 Mechanism of production – produced due to turbulent
blood flow.
 Causes –
 Valvular stenosis
 Valvular insufficiency
 Valvular septal defect.
 Coarctation of aorta
 Types
 Systolic
 Diastolic
 Continuous.
Essentials of Medical physiology (8th edition) by K Sembulingam