STRUCTURE OF HEART

EXTERNAL STRUCTURE OF HEART:

  • Externally the human heart is a muscular, cone-shaped, hollow organ about the size of a fist (about 12cm in length and 9 cm in breadth).
  • The heart is situated behind the sternum, between the lings in the thoracic cavity.
  • The major part of the heart is made up of muscles and is called MYOCARDIUM.
  • The inner lining of the heart is called the ENDOTHELIM.
  • The heart is covered by a membrane called PERICARDIUM.
  • The pericardium encloses the PERICARDIAL CAVITY that houses the heart.

INTERNAL STRUCTURE OF HEART:

  • Internally the human heart is four- chambered.
  • The upper chambers are called the atria or the auricles and the lower two chambers are called the ventricles.
  • The two atria are separated by the INTER-ATRIAL SEPTUM.
  • The two ventricles are separated from each other by the INTER-VENTRICULAR SEPTUM. 

    Structure of human heart










 
  •  The ventricles have more muscular walls than the auricles.
  • An AURICULO – VENTRICULAR aperture connects the ATRIUM with VENTRICLES of its own side.
  • In between the right atrium and right ventricle lies a TRICUPSID CAVITY.
  • Similarly a BICUPSID CAVITY guards the opening between left atrium and left ventricle.
  • The tricuspid and bicuspid valves prevent back flow of blood into the auricles from the ventricles.
  • The two ATRIA contracts simultaneously to push the blood into the respective ventricles.
  • The blood from the right ventricle is pumped through PULMONARY ARCH to the lungs for OXYGENATION while blood from the left ventricle is pumped through aorta to all parts of the body.
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