MODULE 2: CIRCULATORY SYSTEM

• The human heart has four chambers, valves that control blood flow, and major blood vessels attached to it

  
• The circulatory system transports nutrients, gases, and waste products through the body

  
• The circulatory system delivers nutrients obtained from digestion to tissues and organs by pumping oxygenated blood
• Oxygen from inhaled air diffuses into the bloodstream in the lungs, then the heart pumps it to the tissues
• Carbon dioxide is carried back by the blood to the lungs for exhalation
• The circulatory system plays a crucial role in the immune response by transporting immune cells, antibodies, and other defense mechanisms throughout the body
• Circulatory system helps regulate body temperature by adjusting blood flow to the skin to maintain a stable internal body temperature regardless of external conditions
• The circulatory system aids in the coagulation process primarily through blood vessels and blood components
• The cardiovascular system and lymphatic system are major components of the circulatory system
• A blood sample is made up of plasma, Buffy coat, and erythrocytes

  
• Plasma is the liquid part of the blood and makes up about 55% of the total blood volume
• The Buffy coat is a thin layer of white blood cells and platelets, making up about 1% of the total blood volume
• Erythrocytes are red blood cells and make up about 45% of the total blood volume
• They are increased in number in conditions like allergies, asthma, and parasitic infections
• The lymphatic system is a network of vessels and nodes that helps fight infection and maintain fluid balance in the body

  
• It includes lymph capillaries, lymph nodes, lymph ducts, the spleen, and the thymus
• The spleen filters blood and removes old or damaged red blood cells
• The thymus produces lymphocytes, white blood cells that help fight infection
• The lymphatic system is crucial for the body's immune response
• The human heart diagram shows the four chambers, valves controlling blood flow, and major blood vessels attached to the heart

  
• The circulatory system diagram illustrates the flow of oxygenated and deoxygenated blood through the heart and lungs

  
• A blood sample consists of:

  • Plasma (55% of total blood volume): the liquid part of blood
  • Buffy coat (1% of total blood volume): a thin layer of white blood cells and platelets
  • Erythrocytes (45% of total blood volume): red blood cells

  
• The lymphatic system, composed of vessels, nodes, spleen, and thymus, helps fight infection and maintain fluid balance in the body

  
• Capillaries are microscopic, one-cell-thick vessels that connect arterioles and venules, allowing the exchange of oxygen for carbon dioxide and nutrients for waste between cells
• Erythrocytes are the most numerous blood cells, described as nuclear, biconcave disks, containing hemoglobin for oxygen transport, with a lifespan of 120 days
• Leukocytes play a crucial role in defending the body against pathogens through phagocytosis, antibody production, and releasing substances that attack foreign matter
• Hemostasis is the stoppage of bleeding after an injury, involving blood vessels, platelets, plasma proteins, and the coagulation process
• HEART

  It is a hollow, muscular organ which is considered as the major structure of the circulatory system.

  It is the “pump” that forces the blood through the blood vessels

  Located at the center of the thoracic cavity between the lungs with the apex/tip pointing down and to the left of the body

  • Slightly larger than a man’s closed fist
• Pericardium is the thick fluid sack that surrounds the heart and protects it from external forces
• EPICARDIUM

  • Thin outer layer
  • Protective layer that attaches to the pericardium
• MYOCARDIUM

  • Middle muscle layer
  • Contracts to pump blood into the arteries
  • Thick layer of cardiac muscles
• ENDOCARDIUM

  • Thin inner layer
  • Lines the interior chambers and valves
• ATRIA

  • Upper chambers
  • “Receiving” chambers
• VENTRICLES

  • Lower chambers
  • “Pumping” or “delivering” chambers
• RIGHT ATRIUM

  Receives deoxygenated blood from the body, through the superior and inferior vena cava, and pumps it into the right ventricle
• RIGHT VENTRICLE

  Pumps the deoxygenated blood received from the right atrium into the lungs
• LEFT ATRIUM

  Receives oxygenated blood from the lungs throughout the pulmonary veins and pumps it into the left ventricle
• LEFT VENTRICLE

  Pumps the oxygenated blood back to the bodily tissues through the aorta
• The walls of the left ventricles are about 3 times thicker than the right ventricle due to the force required to pump blood into the arterial system
• INTERATRIAL SEPTUM

  • Separates the right and left atria