21.1 An Overview of the Cardiovascular System

• • The cardiovascular system is composed of the heart and a network of blood vessels. The blood vessel network id divided into a pulmonary circuit and a systemic circuit. Each of these circuits begins and ends at the heart
• The heart is a small organ with four muscular chambers

  • right atria
  • left atria
  • right ventricle
  • left ventricle
• The network of vessels is divided into two circuits

  • pulmonary circuit
  • systemic circuit
• The pulmonary circuit carries carbon dioxide rich blood from the heart to the gas exchange surfaces of the lungs and returns oxygen rich blood to the heart
• The systemic circuit transports oxygen rich blood from the heart to the rest of the body's cells and returns carbon dioxide rich blood back to the heart
• Path through the heart chambers

  • Right atrium receives blood from systemic circuit
  • Right ventricle pumps blood into pulmonary circuit
  • Left atrium receives blood from pulmonary circuit
  • Left ventricle pumps blood into systemic circuit
• Each circuit begins and ends at the heart, blood flows through these circuits
• Blood returning to the heart from the systemic circuit must complete the pulmonary circuit before reentering the systemic circuit
• Blood vessels of both circuits are arteries, veins, and capillaries
• Arteries transport blood away from the heart
• Veins return blood to the heart
• Capillaries are small, thin-walled vessels connecting the smallest arteries and veins
• Capillaries are called exchange vessels because their thin walls permit exchange of nutrients, dissolved gases, and wastes between the blood and surrounding tissues
• SUMMARY

  • Cardiovascular system divided into two circuits. Each circuit functions individually in series, while the two circuits together function in parallel.
  • Pulmonary circuit carries O2 poor blood from hear to lungs and back
  • Systemic circuit carries O2 rich blood from heart to body and around.
  • Arteries carry blood away from heart
  • Veins return blood to heart
  • Capillaries are tiny vessels between smallest arteries and veins
• SUMMARY

  • Heart contains four chambers: right atrium and right ventricle, and left atrium and left ventricle
  • Atria collect blood returning to heart
  • Ventricles discharge blood into vessels to leave heart