Cardio1

• Organs of the Cardiovascular System

  • Heart
  • Blood vessels
  • Arteries
  • Arterioles
  • Capillaries
  • Veins
  • Venules
• Responsibilities of cardiovascular system

  • Pumping blood to the body tissues and cells
  • Supplying oxygen and nutrients to tissues and cells
  • Removing carbon dioxide and other waste products of metabolism from tissues and cells
• Heart


  • Approximately the size of your fist
  • Location: Superior surface of diaphragm, left of the midline, anterior to the vertebral column, posterior to the sternum
• Coverings of the Heart: Anatomy


  • Pericardium - a double-walled sac around the heart
• Function of the Pericardium

  • Protects and anchors the heart
  • Prevents overfilling of the heart with blood
  • Allows for the heart to work in a relatively friction-free environment
• Pericardial Layers of the Heart

  • Epicardium
  • Myocardium
  • Endocardium
• Heart


  • Center of the circulatory system
  • Enclosed by pericardium
  • Three layers of the heart: Epicardium, Myocardium, Endocardium
• Heart Chambers


  • Right atrium and left atrium (upper, receiving chambers)
  • Right ventricle and left ventricle (lower, pumping chambers)
• Heart Partitions


  • Interatrial septum (separates right and left sides of atria)
  • Interventricular septum (separates right and left sides of ventricles)
• Heart Valves


  • Tricuspid valve (controls blood flow between right atrium and ventricle)
  • Mitral valve (controls blood movement between left atrium and ventricle)
  • Pulmonary valve (controls blood movement from right ventricle into pulmonary artery)
  • Aortic valve (controls blood flow from left ventricle to the aorta)
• Arteries


  Carry blood away from the heart
• Veins


  Carry blood toward the heart
• Arteries


  • Muscular elastic walls
  • Form arterioles which form capillaries
  • Carry blood and oxygen to the body cells
• Coronary Arteries


  Supply blood to the heart muscle
• The heart needs a large amount of blood and 5-7% of blood flows through the coronary arteries
• The heart uses approximately 3 times more oxygen than other body organs
• Veins


  • Thinner muscular walls
  • Cuplike valves to help move blood
• Capillaries


  • Walls only one cell thick
  • Site for exchange of nutrients and oxygen from blood cells and carbon dioxide and wastes to the blood
• The Great Vessels


  • Superior and inferior venae cavae (bring blood to R atrium from head & body)
  • Pulmonary artery (trunk) (deoxygenated blood to lungs)
  • Right and left pulmonary arteries
  • Pulmonary veins (oxygentated blood from lungs)
  • Aortia (conducts blood to systemic circuit)
• Pulmonary Circulation


  Circulation of blood between the heart and lungs
• Pulmonary arteries


  The only arteries to carry blood low in oxygen
• Pulmonary veins


  The only veins to carry oxygen rich blood
• Systemic Circulation


  Flow of blood between the heart and the cells of the entire body
• Blood Flow


  1. Blood travels through the body in a surge as a result of the heart contractions

  2. Blood vessels become smaller in diameter as the blood leaves the heart

  3. Arteries leave the heart and veins return to the heart

  4. Capillaries are the smallest blood vessels and they serve as a transfer station between the arteries and veins
• Pathway of Blood Through the Heart and Lungs

  1. Right atrium -> tricuspid valve -> right ventricle

  2. Right ventricle -> pulmonary semilunar valve -> pulmonary arteries -> lungs

  3. Lungs -> pulmonary veins -> left atrium

  4. Left atrium -> bicuspid valve -> left ventricle

  5. Left ventricle -> aortic semilunar valve -> aorta

  6. Aorta -> systemic circulation
• Conduction System


  • Purkinje Fibers
  • Sinoatrial node (Pacemaker)
  • Atrioventricular node
  • Bundle of His
  • Right and Left Bundle Branches
• Conduction System of the Heart

  1. Sinoatrial Node (SA Node) sets rhythm for entire heart

  2. Impulse from SA node causes atria to contract

  3. Impulse travels from SA node to Atrioventricular node (AV node)

  4. Impulse from AV node travels to ventricles through Bundle of His

  5. Bundle of His divides into right and left bundle branches

  6. Bundle branches terminate in Purkinje fibers

  7. Purkinje fibers fan out into the muscles of the ventricles

  8. Purkinje fibers cause ventricles to contract
• Cardiac Cycle


  The electrical and physical events of an entire heart beat - 0.7 seconds
• Phases of the Cardiac Cycle

  • Diastole - resting phase, no active contraction
  • Systole - active muscle contraction and electrical impulses
• Diastole


  Relaxation phase of heartbeat, ventricles relax and fill with blood
• Systole


  Contraction phase of heartbeat, ventricles contract and force blood out of heart
• Cardiac Output (CO)


  The amount of blood pumped by each ventricle in one minute
• Cardiac Output


  The product of heart rate (HR) and stroke volume (SV)
• Heart Rate (HR)


  The number of heart beats per minute
• Stroke Volume (SV)


  The amount of blood pumped out by a ventricle with each beat
• Cardiac Reserve


  The difference between resting and maximal CO
• Factors Affecting Stroke Volume

  • Preload - amount ventricles are stretched by contained blood
  • Contractility - cardiac cell contractile force
  • Afterload - back pressure exerted by blood in the large arteries leaving the heart
• Frank-Starling Law of the Heart

  • Preload, or degree of stretch, of cardiac muscle cells before they contract is the critical factor controlling stroke volume
  • Slow heartbeat and exercise increase venous return to the heart, increasing SV
  • Blood loss and extremely rapid heartbeat decrease SV
• Positive chronotropic factors (increase heart rate)


  • Caffeine
• Negative chronotropic factors (decrease heart rate)


  • Sedatives