ANATOMY AND PHYSIOLOGY OF HEART

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Cardiology : core components for nurses

 

Anatomy and physiology

Heart is the vital organ which is located in the left side of medisternium in the thoracic cavity. Normal weight of the heart is 300gm

Layers
  • Epicardium (outer layer)
  • Myocardium (middle layer )
  • Endocardium (inner layer )
Pericardium  ; –

encase and protect the heart from trauma and infection

Layers of pericardium
  • Parietal layer
  • Visceral layer

There is a sac in between these two layer, known as pericardial sac. And fluid which is present between these layers known as pericardial fluids normal amount is 5 to 20 ml





HEART CHAMBER

Atrium-
  • Right atrium (impure blood from IVC, and SVC)
  • Left atrium (pure blood from lung)
Ventricle
  • Right ventricle (impure blood from RA and from RV to lung)
  • Left ventricle (pure blood from LA and from LV to aorta )

 

HEART VALVES
  • AV valves
    • Tricuspid valve, between RA and RV
    • Bicuspid valve, between LA and LV otherwise known as mitral valve
  • Semilunar valves
    • Pulmonary valve, between RV and pulmonary artery .
    • Aortic valve, between LV and aorta.
BLOOD VESSEL ATTACHED TO HEART
  • Superior vena cava(SVC)
  • Inferior vena cava (IVC)
  • Pulmonary vein, there are 4 pulmonary vein carrying pure blood from lung. to LA
  • Pulmonary artery, starting from RV and carrying impure blood to lung for purification
  • Aorta, starting from LV and carrying pure blood for systemic circulation
AORTA
  • Ascending aorta
  • Arch of aorta
  • Descending aorta
ASCENDING AORTA
  • Left coronary artery
    • Anterior descending artery
    • Circumflex artery
  • Right coronary artery
    • Posterior descending artery
    • Marginal artery
ARCH OF AORTA
  • Brachio-cephalic artery
    • RT common carotid artery
    • RT subclavian artery
  • Left common carotid artery
  • Left sub clavian artery
CONDUCTION SYSTEM OF HEART

SA node(sinoatrial node) :- primary pace maker, produce impulses 60 to 100b/min




AV node (atrioventricular  node ):- secondary pace maker, provide pulse 40 to 60 b/min

The bundle of His:- it start from  AV node , and branches to Rt and Lt bundle branch and it extent to ventricle

Purkinje fibers :- Rt and Lt  bundle of His terminate into purkinje fibers, and located  beneath the ventricular endocardium. These spreads the waves of depolarization through the ventricle

HEART SOUNDS
Normal heart sounds –
  • S1:- heard at the closure of AV valve: for tricuspid valve sound Rt side 2nd intercostals space  and for mitral valve sound :Lt side 2nd intercostals space
  • S2 :- closure of Semilunar valve: pulmonary valve sound heard at Rt 4th intercostals   space  and for aortic valve sound heard at Lt 5th intercostals space
Abnormal heart sound
  • S3 :- sound heard with ventricular failure and valvular regurgitation , and congestive heart failure it is normal in person less than 30years
  • S4 :-it is heard with, pulmonary and aortic stenosis, atrial systole, cardiac hypertrophy, resistance to ventricular filling
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