Cardiovascular System

• Cardiovascular system


  A closed circuit that consists of the heart and blood vessels (arteries, capillaries, and veins)

  
• A functional cardiovascular system is vital for supplying oxygen and nutrients to tissues and removing wastes from them
• Arteries


  Transport blood away from the heart
• Veins


  Transport blood toward the heart

  
• Capillaries


  Vessels that run between arteries and veins

  
• Pulmonary circuit


  Oxygen-poor blood is carried to the lungs, where it picks up oxygen and drops off carbon dioxide
• Systemic circuit


  Oxygen-rich blood is sent to all body cells, where it drops of oxygen and picks up carbon dioxide

  
• Heart


  A hollow, cone-shaped, muscular pump within the mediastinum in the thoracic cavity

  
• Heart


  • 4-chambered structure with 2 atria having relatively thin walls, and highly muscular ventricles
  • Base lies beneath the second rib
  • Apex extends to the fifth intercostal space
• Endocardium


  Single layer squamous epithelium - endothelium which also lines with blood vessels
• Myocardium


  Cardiac muscles (cardiomyocyte) that enable the heart to beat
• Epicardium


  Visceral serous pericardium that forms the outer surface of the heart and secretes fluids to reduce friction
• Pericardium


  Membranes that surround the heart and hold it in position, providing protection

  
• Pericardium


  • Fibrous pericardium (outer, tough, connective tissue)
  • Serous pericardium (inner, more delicate, double-layered membrane)
• Parietal pericardium


  Outer layer of the serous membrane that lines the inner surface of the fibrous pericardium
• Visceral pericardium (epicardium)


  Inner layer of the serous membrane that covers the heart

  
• Pericardial cavity


  Space between the visceral and parietal layers of the serous pericardium, containing pericardial fluid
• Pericardial fluid


  Secreted by epicardium and parietal serous pericardium into the pericardial space, reducing friction as the heart beats
• Atria


  Upper chambers of the heart that receive blood returning to the heart, with thin walls and ear-like auricles projecting from their exterior

  
• Ventricles


  Lower chambers of the heart that pump blood out of the heart, with thick muscular walls

  
• Septum


  Structure that separates the atrium and ventricle on the right from those on the left
• Atrioventricular (AV) valves


  Valves that ensure one-way flow of blood from atria to ventricles

  
• Tricuspid valve


  AV valve on the right side of the heart

  
• Bicuspid (Mitral) valve


  AV valve on the left side of the heart

  
• Chordae tendineae


  Attach to the cusps of the AV valves
• Papillary muscles


  Contract during ventricular contraction to prevent the backflow of blood through the AV valves
• Semilunar valves


  Normally closed valves that open when the ventricles contract to allow blood flow out of the heart

  
• Pulmonary valve


  Semilunar valve on the right side of the heart

  
• Aortic valve


  Semilunar valve on the left side of the heart

  
• Heart sounds


  "Lub-dub" - first sound caused by AV valve closure, second sound caused by semilunar valve closure

  
• Heart murmur


  Abnormal sound caused by valve leakage or deformity

  
• Right heart


  Oxygen-poor blood returns to the right atrium, flows through the tricuspid valve into the right ventricle, then is pumped through the pulmonary valve into the pulmonary arteries

  
• Left heart


  Oxygen-rich blood returns to the left atrium, flows through the mitral valve into the left ventricle, then is pumped through the aortic valve into the aorta

  
• Pulmonary circuit


  Blood flow between heart and lungs for gas exchange

  
• Systemic circuit


  Blood flow between heart and body tissues to deliver oxygen and nutrients, and remove waste

  
• The heart is a muscular organ that acts as a pump, driving blood through the blood vessels

  
• Deoxygenated blood is confined to the right side of the heart, and oxygenated blood to the left, with two simultaneous blood streams circulating

  
• Functions of the heart

  • Keeps oxygen-poor and oxygen-rich blood separate
  • Keeps blood flowing in one direction
  • Creates blood pressure
  • Regulates blood supply
  • Serves as an endocrine gland

  
• Atrial natriuretic hormone


  Hormone secreted by the heart that lowers blood pressure and maintains homeostasis
• Heart cells are not nourished by the blood in the heart chambers, so the left and right coronary arteries branch from the aorta to supply the heart muscle