Finals: Lesson 15 - Heart as a Tireless Pump

• Located in the mediastrium. Similar to the shape of a pine cone. About 12cm (5 in) in length, 8 cm (3.5 in) wide, and 6cm (2.5 in) in thickness.

  Human Heart
• The four chambered heart

  1. Right and left atrium
  2. Right and left ventricle
• Receiving chambers


  Right & Left Atrium
• Pumping chambers


  Right & Left Ventricle
• It receives and pumps oxygen poor blood.

  Right side of the heart
• It receives and pumps oxygen rich blood

  Left Side of the Heart
• What are the heart muscles?

  1. Epicardium
  2. Myocardium
  3. Endocardium
• Outermost layer of the heart

  Epicardium
• Thickest layer of the heart

  Myocardium
• Lines chambers, covers the heart valves, secretes endothelins, which are potent vasoconstrictors

  Endocardium
• Extension of the myocardium lined with endocardium.


  Septa or Septum
• Ensures one way flow of blood

  Valves
• What are the chambers of the heart?

  1. Right Atrium
  2. Right Ventricle
  3. Left Atrium
  4. Left Ventricle
• It receives venous blood

  Right Atrium
• Receives blood from right atrium

  Right Ventricle
• Receives oxygen-rich blood


  Left Atrium
• Ejects blood into the aorta

  Left Ventricle
• Coronary Arteries

  1. Right coronary arteries
  2. Left coronary arteries
• Distributes blood to the right atrium and ventricle and the heart conduction system.

  Right Coronary Artery
• Distributes blood to the left side of the heart, left atrium andleft ventricle

  Left Coronary Artery
• Generally parallel to the large surface arteries.

  Coronary Veins
• Receives venous blood from posterior, middle, and small cardiac vein which drains directly to into the right atrium.

  Great Cardiac Vein
• Ability to initiate an electrical potential at a fixed rate.

  Autorhythmicity
• Types of Cardiac Muscle cells

  1. Myocardial Contractile Cells
  2. Myocardial Conducting cells
• 99% of the attia and ventricles

  Myocardial Contractile Cells
• From the conduction system of the heart, specialized muscle cells.

  Myocardial Conducting Cells
• Establish the normal cardia rhythm, the pacemaker of the heart.

  Sionatrial Node (SA node)
• Transmits impulse to the atrioventricular bundle.

  Atrioventicular (AV node)
• bundle branches and Purkinjie fibers

  Atrioventricular Bundle
• Entirely aerobic. Heart cells stores appreciable amount of oxygen in myogoblin

  Cardiac Muscle Metabolism
• Period of contraction that the heart undergoes while it pumps blood

  Systole
• Period of relaxation that occurs as the chambers fill with blood

  Diastole