Lesson 3: THE CIRCULATORY SYSTEM

• The circulatory system is responsible for transporting throughout the body oxygenated blood from the heart and lungs via the arteries. Then the oxygen-depleted blood is returned to its origin through the veins.
• The circulatory system delivers the oxygen and nutrients to all cells in the human body. It transports carbon dioxide and other wastes to the other organs of the body and away from the cells. It helps in the coagulation process, regulates body temperature, and assists the body in fighting diseases.
• The circulatory system is made up of two main components

  Cardiovascular system and lymphatic system
• Is composed of the heart, blood vessels, and blood which helps in the circulation

  Cardiovascular system
• Is made up of the lymph, lymph nodes, and vessels

  Lymphatic system
• Is a hollow muscular organ that has four chambers and is surrounded by a thin, fluid-filled sac

  Heart
• The thin, fluid-filled sac that surrounds the heart

  Pericardium
• A human heart is about the same size as that of a person's clenched fist.
• Familiarize the blood flow in the heart.

  
• Layers of the heart:

  1. Epicardium
  2. Myocardium
  3. Endocardium
• Thin, water membrane on the outer layer of the heart

  Epicardium
• Its function is to cover the heart and is attached to the pericardium

  Epicardium
• Thick layer of cardiac muscles in the middle layer of the heart

  Myocardium
• Its function is to pump blood into the arteries by contracting

  Myocardium
• Thin layer of epithelial cells in the inner layer of the heart

  Endocardium
• Its function is to line the valves and interior chambers

  Endocardium
• Upper right chamber


  Right atrium
• Receives deoxygenated blood from the body

  Right atrium
• Lower right chamber

  Right ventricle
• Receives blood from the upper right chamber of the heart and pumps it into the pulmonary artery

  Right ventricle
• Upper left chamber

  Left atrium
• Receives oxygenated blood from the lungs and pumps it into the lower left chamber

  Left atrium
• Lower left chamber

  Left ventricle
• Receives blood from the left upper chamber and pumps it into the aorta

  Left ventricle
• Located between the right atrium and right ventricle

  Right AV valve
• Right AV valve is also called the

  Tricuspid valve
• Closes as the right ventricle contracts preventing blood from flowing back to the right atrium

  Right AV valve
• Locate between the left atrium and the left ventricle

  Left AV valve
• Left AV valve is also called the

  Bicuspid or mitral valve
• Closes as the left ventricle contracts preventing blood from flowing back to the left atrium

  Left AV valve
• Located at the entrance of the pulmonary artery. Also called the pulmonary or pulmonic valve


  Right semilunar valve
• Closes when the right ventricle relaxes preventing blood from flowing back to the right ventricle

  Right semilunar valve
• Also called the aortic valve, is located at the entrance of the aorta

  Left semilunar valve
• Closes when the left ventricle relaxes preventing blood from flowing back to the left ventricle.

  Left semilunar valve
• Partition that separates the right from the left atria

  Interatrial septum
• Separates the right and left ventricles

  Interventricular septum
• Coronary circulation is when the heart reveives blood supply through the left and right coronary arterieis, and the coronary veins return the oxygen-depleted blood from the heart muscle back to the heart.
• The coronary circulation supplies the blood as well as provides drainage to the tissues.
• Coronary circulation is composed of the left and right coronary arteries and coronary veins.
• Poor circulation could lead to ischemia which is caused by inadequate supply of oxygen and myocardial infarction or heart attack which may be due to complete obstruction of the coronary artery.