Structure of the heart & its conducting system

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Structure of the heart its conducting system

• DR. Karam
• CVS module/ week2

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Location of the heart

• The heart is a hallow shape muscular organ that
  is located in the middle mediastinum

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Pericardium

• The heart is surrounded by pericardium that
  restrict excessive movement of the heart
• 2 types of pericardium
• Fibrous pericardium
• Serous pericardium
• Parietal layer the lies the fibrous pericardium.
• Visceral layer that lies the heart.

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Surfaces of the heart

• Sternocostal surface ( anterior) Rt atrium Rt
  ventricle
• Diaphragmatic surface( Inferior) Rt Lt
  ventricles
• Base of the heart (posterior) Lt atrium
• Apex of the heart mainly Lt ventricle

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Borders of the heart

• Right border Rt atrium
• Left border Lt auricle/ Lt ventricle
• Inferior border Rt ventricle

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Walls of the heart

• Myocardium Cardiac muscle
• Epicardium visceral layer of the serous
  pericardium
• Endocardium internal lining of the heart

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Chambers of the heart

• Right atrium
• Most of its wall is smooth but some are rough.
  This is known as muscli pectinati
• Openings in the Rt atrium
• SVC
• IVC
• Coronary sinus
• Fossa Ovalis embryonic ruminant of foramen
  ovali.

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Chambers of the heart

• Right Ventricle
• Communicates with the right atrium via Rt AV
  orifice ( guarded by tricuspid valve) with the
  Pulmonary Artery via Pulmonary orifice( guarded
  by pulmonary valve).

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Chambers of the heart

• Left Atrium
• 4 pulmonary veins open in the left atrium and it
  communicates with the left ventricle via Lt AV
  orifice that is guarded by the mitral valve.

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Chambers of the heart

• Left Ventricle
• Communicated with the left atrium by Lt AV
  orifice ( guarded by mitral valve) and the aorta
  via the aortic orifice ( guarded by aortic valve).

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Conducting system of the heart

• The conducting system of he heart is made of
  specialized cardiac muscles
• Sinoatrial node
• Atrioventricular node
• Atrioventricular bundle
• Right left bundle branches
• Purkinji fibers

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Blood supply of the heart

• The blood supply of the heart is mainly from the
  left and the right coronary arteries, which
  arises from the ascending aorta.
• The main branches from the Rt coronary artery (
  Posterior interventricular artery the marginal
  artery)
• The main branches of the Lt coronary artery (
  Anterior interventricular artery circumflex
  artery)

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Nerve supply of the heart

• The heart is supplied by sympathetic and
  parasympathetic fibers of the Autonomic nervous
  system via the cardiac plexus.
• The sympathetic fibers arises from the lower
  cervical and upper thoracic vertebrae.
• The parasympathetic fibers arises from the vagus
  never.

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Valves of the heart

• AV valves
• Tricuspid valve that guard the RT AV orifice
  located in the RT half of the sternum in the 4th
  intercostal space. It could be heard at the Rt
  half the lower end of the sternum body
• Mitral valve that guard the LT AV orifice
  located in the LT half of the sternum in the 4th
  intercostal space. It could be heard at the Apex
  of the heart

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Valves of the heart

• Semilunar valves
• Pulmonary valves located in Lt the medial end of
  the 3rd costal cartilage it is best heard at
  the Lt medial 2nd intercostal space
• Aortic valve located in the Lt half of the
  sternum in the 3rd intercostal space best heard
  in the medial 2nd Rt inetercostal space.

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Histology of the heart

• The cardiac muscles are found in the wall of the
  heart. It is striated (like skeletal muscles) but
  has a specific characteristics
• Uninucleated
• Branching cell that fit together by interclating
  disc