Cardiovascular

• Heart


  • Hollow cone shaped
  • Weighs about 250-350 grams
  • Snugly enclosed within the mediastinum
  • Extends obliquely from the second rib to the fifth intercostal space
  • Rests on the superior surface of the diaphragm
  • Lies anterior to the vertebral column and posterior to the sternum
  • Approximately 2/3rd of its mass lies left of the midsternal line
• Pericardium


  Double walled sac that encloses the heart
• Coverings of the heart

  • Fibrous pericardium
  • Parietal pericardium
  • Visceral pericardium (epicardium)
• Pericardial cavity


  Slit like space between the parietal and visceral layers of the pericardium, containing serous fluid
• The serous membranes of the heart allow the heart to work in a relatively friction free environment
• Layers of the heart wall

  • Epicardium
  • Myocardium
  • Endocardium
• Heart chambers


  • Two superior atria
  • Two inferior ventricles
• Interatrial septum


  Internal partition that divides the atria
• Interventricular septum


  Internal partition that divides the ventricles
• Right ventricle


  • Forms most of the anterior surface of the heart
• Left ventricle


  • Dominates the infero-posterior aspect of the heart and forms the heart apex
• Blood vessels entering the right atrium

  • Superior vena cava
  • Inferior vena cava
  • Coronary sinus
• Blood vessels entering the left atrium

  • Four pulmonary veins
• Trabeculae carneae


  Irregular ridges of muscle in the ventricular chambers
• Papillary muscles


  Cone like muscle bundles that project into the ventricular cavity and play a role in valve function
• Ventricles


  Discharging chambers or actual pumps of the heart
• Blood vessels arising from the ventricles

  • Pulmonary trunk (from right ventricle)
  • Aorta (from left ventricle)
• Pulmonary circuit


  Blood vessels that carry blood to and from the lungs, serving gas exchange
• Systemic circuit


  Blood vessels that carry the functional blood supply to and from all body tissues
• Coronary arteries


  • Right coronary artery
  • Left coronary artery
  • Anterior interventricular artery
  • Circumflex artery
  • Posterior interventricular artery
  • Right marginal artery
• There are many anastomoses (junctions) among the coronary arterial branches, providing additional (collateral) routes for blood delivery to the heart muscle
• Collateral circulation


  Additional blood supply routes that can overcome moderate ischemia caused by partial coronary artery blockage
• Cardiac veins


  • Coronary sinus
• Heart valves


  • Atrioventricular valves
  • Semilunar valves
• Atrioventricular valves


  Prevent backflow of blood during ventricular systole
• Types of atrioventricular valves

  • Tricuspid valve
  • Mitral valve
• Chordae tendineae


  Collagen cords that anchor atrioventricular valves to the papillary muscles, preventing valve eversion during ventricular systole
• Types of semilunar valves

  • Aortic valve
  • Pulmonary valve
• Semilunar valves


  Prevent backflow of blood into the associated ventricles
• Common valve deformities


  • Incompetent valve
  • Stenosed valve
• Deformities of the heart valves can seriously hamper cardiac function. Congenital heart diseases and rheumatic heart diseases are the common causes of valve deformities
• Chordae tendineae


  Prevent the atrioventricular valves from everting during ventricular systole
• Semilunar valves


  • Aortic
  • Pulmonary
• Aortic valve

  Present at the base of aorta which is arising from the left ventricle
• Pulmonary valve

  Valves are present at the base of pulmonary artery which is arising from the right ventricle
• Function of semilunar valves

  Prevent back flow of blood into the associated ventricles
• Heart valve deformities

  • Incompetent valve - does not close properly and blood backflows
  • Stenosed valve - valve flaps become stiff and constrict the opening, compels the heart to contract more forcibly than normal
• Under conditions of heart valve deformities, the faulty valve is replaced by a mechanical valve or cryopreserved valves from human cadavers
• Body's vital signs

  • Pulse
  • Blood pressure
  • Respiratory rate
  • Body temperature
• Monitoring of body's vital signs is important to know person's circulatory efficiency