anatomy & physiology of the heart in detail

2. Anatomy and Physiology of the
Heart

3. Contents
 Anatomy of the heart
 Physiology of the heart
 Conduction system of the heart
 Arterial and Venous system
 Cardiac auscultation

5.  Normally located in the middle and slightly to the left side of the thoracic
cavity on the diaphragm between 3rd and 5th ribs.
 Weighs about 325 gm is males and about 275 gm in females.

6. Heart has
 Base
 Apex
 Anterior
 Posterior

8. Four chambers
 Right Atrium
 Right Ventricle
 Left atrium
 Left ventricle

10. Right Atrium
 Receives venous blood from whole of
the body via the superior vena cava
(SVC) at its upper end and inferior vena
cava (IVC) at its lower end.
 It pumps into Right ventricle (RV)
through the tricuspid valve during the
ventricular diastole.
 Right atrial appendage – arises from the
antero superior part of the right atrium. It
is to the left of the ascending aorta.
 Sulcus terminalis – shallow vertical
groove along the right heart border
between SVC and IVC.
 RA and SVC junction – Sino atrial
node.

11. Right ventricle
 Triangular shaped or
crescent shaped
 Opens into pulmonary artery
through pulmonary valve
 Most anterior chamber
 RV wall measures 4-5 mm in
thickness.
 Three portions – inflow ,
outflow and apical trabecular
portion or body of RV.

12. Left atrium
 Posterior most chamber
 Receives oxygenated blood
from pulmonary veins
 Pulmonary veins open into
LA from the posteriorwall
 Left atrial appendage is
anterior.

13. Left ventricle
 Bullet shaped
 Blunt tip forms the apex
of the heart
 LV wall is 8-15 mm in
thickness.

14. Three layers
 Outer Epicardium
 Middle Myocardium
 Inner Endocardium
 And a covering Pericardium

15. Pericardium
 The pericardial sac has two layers,
 a serous layer and
 a fibrous layer.
 It encloses the pericardial cavity which
contains pericardial fluid.
 The pericardium fixes the heart to the mediastinum, gives
protection against infection, and provides the lubrication for
the heart.
 The pericardial sac normally contains up to 50 mL of fluid.

16. Epicardium
 Outer most layer of the heart.
 Visceral layer of pericardium.

17. Myocardium
 Thicker middle layer of the heart
 Composed of individual heart
muscle cells called as
cardiomyocytes.
 Joined together by intercalated
disks
 Encased by collagen and other
substances forming the
extracellular matrix
(INTERSTITIUM).

18. Endocardium
 Its cells are embryologically and biologically similar to the
endothelial cells that line blood vessels.

19. Applied anatomy
 Pericarditis
 Pericardial effusion
 Pericardial window
 Pericardiectomy
 Constrictive Pericardits
 Myocarditis
 Interstitial myocarditis
 Infective endocarditis
 Epicardial pacing
 Myocardial biopsy

20. Four valves
 Mitral valve
 Aortic valve
 Tricuspid valve
 Pulmonic valve

21.  Mitral and tricuspid valves are called as
ATRIOVENTRICULAR
valves.
 Mitral valve has two leaflets. (Anterior and Posterior)
 Tricuspid valve has three leaflets (Anterior, Septal and
Posterior)
 Aortic and Pulmonary valves are called as
SEMILUNAR valves.
 Aortic valve has three cusps right coronary cusp, left
coronary cusp and non coronary cusp.
 Pulmonic valve has three cusps.

23. Applied anatomy
 Mitral stenosis
 Mitral Valve prolapse
 Mitral regurgitation
 Tricuspid stenosis
 Tricuspid regurgitation
 Aortic stenosis
 Aortic regurgitation
 Pulmonic stenosis
 Pulmonic regurgitation

24. Two great arteries
 Aorta
 Pulmonary artery

25. Chest x ray correlation

26. Physiology of heart
 Systole - contraction
 Diastole – relaxation
 Atrial systole
 Atrial diastole
 Ventricular systole
 Ventricular diastole
 Systole is 0.3 sec
 Diastole is 0.5 sec
 Total cardiac cycle is 0.8 sec

28. Applied physiology
 Contraction of muscles occurs due to calcium influx.
 Increased contractility – positive inotropes – dobutamine
 Decreased contractility - negative inotropes – beta
blockers
 Increased relaxation – lusitropic
 Decreased heart rate – chronotropic – calcium channel blockers
 Increased conduction – bromotropic

29. Cardiac output
 CO = SV X HR
 For a resting adult
CO = 70mL/beat x75beats/min
= 5250 mL/min
= 5.25 L/min

30. Stroke volume
 Regulation of stroke volume is by three factors
 PRELOAD
 CONTRACTILITY
 AFTERLOAD

31. Preload
 Stretch of cardiac muscle prior to
contraction.
 Frank-starling law
 Preload is propotional to End Diastolic
Volume
 If HR is more than 160 beats/min stroke
volume declines due to short filling time.

32. Contractility
 It is the strength of contraction
at any given preload.
 Positive and Negative
inotropics.
 Stimulation of sympathetic
division of ANS leads to positive
inotropic effect
 Inhibition of sympathetic
division of ANS leads to
negative inotropic effect

33. Afterload
 The pressure that must be overcome before a semilunar
valve can open is termed the afterload.
 Increase in afterload causes decrease in stroke volume
 HTN and atherosclerosis increases the afterload.