Heart PowerPoint

• Cardiovascular system


  A closed system of the heart and blood vessels

  
• Cardiovascular system


  • The heart pumps blood
  • Blood vessels allow blood to circulate to all parts of the body

  
• Functions of the cardiovascular system

  • Transport oxygen
  • Transport nutrients
  • Transport cell wastes
  • Transport hormones to and from cells
• Heart


  Size of a human fist, weighing less than a pound
• Location of the heart

  Located in the thoracic cavity, between the lungs in the inferior mediastinum (medial section of the thoracic cavity)

  
• Orientation of the heart

  • Apex (pointed region) is directed toward left hip and rests on the diaphragm
  • Base (area where great blood vessels emerge) points toward right shoulder
• Pericardium


  A double-walled sac that covers the heart
• Layers of the pericardium

  • Fibrous pericardium (loose and superficial)
  • Parietal pericardium (outside layer that lines the inner surface of the fibrous pericardium)
  • Visceral pericardium (next to heart; also known as the epicardium)

  
• Pericardial cavity


  Space between the layers of pericardium filled with serous fluid
• Layers of the heart wall

  • Epicardium (outermost layer; also known as the visceral pericardium)
  • Myocardium (middle layer composed mostly of cardiac muscle)
  • Endocardium (inner layer known as endothelium)
• Pericarditis


  Inflammation of the pericardium, can be acute (sudden) or chronic (gradual)
• Myocarditis


  Inflammation of the myocardium, usually a complication of a viral infection
• Endocarditis


  Inflammation of the endocardium, typically due to bacteria, and usually involves the heart values
• Chambers of the heart

  • Atria (right and left)
  • Ventricles (right and left)
• Atria


  Superior receiving chambers that assist with filling the ventricles, blood enters under low pressure from veins of the body
• Ventricles

  Inferior discharging chambers that are thick-walled pumps of the heart, during contraction blood is propelled into circulation
• Interatrial septum


  Separates the two atria longitudinally
• Interventricular septum


  Separates the two ventricles longitudinally
• Heart as a double pump

  Right side works as the pulmonary circuit pump, left side works as the systemic circuit pump
• Pulmonary circulation


  Blood flows from the right side of the heart to the lungs and back to the left side of the heart

  
• Systemic circulation

  Oxygen-rich blood returned to the left side of the heart is pumped out into the aorta and circulates to systemic arteries and to all body tissues, oxygen-poor blood returns to the right atrium via systemic veins

  
• Heart valves

  Allow blood to flow in only one direction to prevent backflow
• Types of heart valves

  • Atrioventricular (AV) valves (mitral and tricuspid)
  • Semilunar valves (pulmonary and aortic)
• Atrioventricular (AV) valves


  • Chordae tendineae anchor the cusps to the walls of the ventricles
  • Open during heart relaxation, when blood passively fills the chambers
  • Closed during ventricular contraction
• Semilunar valves


  • Closed during heart relaxation
  • Open during ventricular contraction
• Coronary arteries


  Branch from the aorta to supply the heart muscle with oxygenated blood

  
• Coronary arteries

  • Anterior interventricular artery
  • Circumflex artery
  • Posterior interventricular artery
  • Marginal artery
• Cardiac veins


  Drain the myocardium of blood
• Coronary sinus


  A large vein on the posterior of the heart that receives blood from cardiac veins and empties into the right atrium
• Myocardial ischemia


  Reduced blood flow to the myocardium, can cause hypoxia and angina pectoris
• Myocardial infarction


  Heart attack, infarction refers to death of tissues due to interrupted blood supply
• Intrinsic conduction system of the heart

  Sets the heart rhythm and ensures heart muscle depolarization in one direction only (atria to ventricles)
• Components of the intrinsic conduction system

  • Sinoatrial (SA) node
  • Atrioventricular (AV) node
  • Atrioventricular (AV) bundle (bundle of His)
  • Bundle branches
  • Purkinje fibers
• Intrinsic conduction system function

  1. SA node starts each heartbeat

  2. Impulse spreads through the atria to the AV node

  3. Atria contract

  4. Impulse is delayed briefly at the AV node

  5. Impulse travels through the AV bundle, bundle branches, and Purkinje fibers

  6. Ventricles contract, blood is ejected from the heart

  
• Tachycardia


  Rapid heart rate, over 100 beats per minute
• Bradycardia


  Slow heart rate, less than 60 beats per minute
• Cardiac cycle


  One complete heartbeat, in which both atria and ventricles contract and then relax
• Phases of the cardiac cycle

  • Atrial diastole (ventricular filling)
  • Atrial systole
  • Isovolumetric contraction
  • Ventricular systole (ejection phase)
  • Isovolumetric relaxation
• Average heart rate is approximately 75 beats per minute
• Cardiac cycle length is normally 0.8 second