Structure and function of the human heart

• What is the shape of the human heart?


  Roughly a cone shaped hollow muscular organ
• What are the three layers of tissues the heart wall is composed of?

  Pericardium, myocardium and endocardium
• What is Pericardium?


  The pericardium is the outermost layer. it is made up of two sacs
• What are the two sacs of pericardium?


  Outer fibrous pericardium and inner serous pericardium
• What is myocardium?


  Myocardium is the middle layer of the heart wall.
• Myocardium is composed of what?

  Specialized cardiac muscle found only in the heart
• What is running through the myocardium?

  network of specialized conducting fibers
• Specialized conducting fibers running through the myocardium is responsible for what?

  transmitting the heart's electrical signals
• It What is Endocardium?

  It is the inner layer of the heart wall. it lines the chambers and the valves of the heart. it is a smooth membrane and consists of flattened epithelial cells. it is continuous with the endothelium lining of the blood vessels.
• How many chambers are in the heart?

  Four chambers; two upper atria and two lower ventricles
• Why are the walls of the ventricles are thicker than the walls of the atria ? 


  Ventricles have to pump blood to the whole body. Where as atria pump blood to the ventricles only.
• Why are the walls of left ventricle is thicker than walls of the right ventricle?

  Right ventricle pumps blood to the lungs which are closer to the heart whereas the left ventricle has to pump blood throughout the body
• How about the blood from right and left ventricle?

  Blood entering aorta from the right atrium is at much higher blood pressure than the blood entering the pulmonary artery from right ventricle
• How is the heart completely divided into right and left side?

  Septum
• The atria and ventricles on each side are divided by what?

  Atrio-ventricular valve (AV)
• How many flaps are there in atrio ventricular valves in right and left ventricles?


  right - three flaps (tricuspid valve)

  left - two flaps (bicuspid valve)
• What are conical shaped papillary muscles? 


  Extensions of the inner walls of the ventricles
• What are chordae tendinea?

  Atrio-ventricular valves attached to the papillary muscles by strong fibers
• What’s the use of strong fibers?

  Atrio-ventricular valves are anchored by strong fibers. This prevents the valves from being turned inside out
• Where are the semilunar valves can be found?


  Points where the pulmonary artery and the aorta leave right and left ventricles respectively.
• What is the use of semi lunar valves? 


  Prevent the backflow of blood into the ventricles
• How does the pulmonary artery with oxygen poor blood leave the heart?

  From the upper part of the right ventricle
• What happens to the pulmonary artery after it leaves from the upper part of the right ventricle?

  Pulmonary artery divides into left and right pulmonary arteries and carries oxygen poor blood to the lungs
• How does the oxygen rich blood is carried to the left atrium?

  Two pulmonary veins from each lung carry oxygen rich blood back to left atrium
• How does the aorta leaves?

  aorta with oxygen rich blood leaves from the upper Part of the left ventricles.
• What will superior and inferior vena cava will do?

  Superior and inferior vena cava open into the right atrium and empty their contents into the right atrium
• How is the heart is supplied with arterial blood? 


  by the right and left coronary arteries which branch from the aorta immediately after the aortic valve