cardio

• Cardiovascular system

  Delivers oxygen and nutrients to the body tissues and carries away wastes such as carbon dioxide via blood
• Heart


  • Size of a fist; about 1 lb
  • Hollow and cone shaped
  • In the mediastinum; medial section of the thoracic cavity
  • Has pointed apex pointing towards the left hip and a broad base from which the great vessels arise
• Pericardium


  Sac that encloses the heart, made up of three layers: outer fibrous layer, inner serous membrane pair, and parietal and visceral pericardium
• Serous pericardial fluid


  Lubricates the heart to allow it to beat easily in a relatively frictionless environment
• Walls of the heart

  • Epicardium (visceral pericardium)
  • Myocardium (middle muscular layer)
  • Endocardium (lines the heart chambers)
• Atria


  Superior, primarily receiving chambers that assist with filling the ventricles
• Ventricles

  Inferior, thick-walled discharging chambers that are the actual pumps of the heart
• Interatrial septum


  Divides the atria
• Interventricular septum


  Divides the ventricles
• Pulmonary circulation


  Carries blood to the lungs for gas exchange
• Systemic circulation


  Carries oxygen-rich blood from the left ventricle through the body tissues and back to the right atrium
• Heart valves

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


  Open during heart relaxation, closed when ventricles are contracting
• Semilunar valves


  Closed during heart relaxation, forced open when ventricles contract
• Coronary arteries and veins


  Provide the functional blood supply that oxygenates and nourishes the myocardium
• Conduction system

  Intrinsic system that regulates the pumping of the heart
• Conduction system components

  • SA node
  • AV node
  • Bundle of His
  • Right and left bundle branches
  • Purkinje fibers
• Cardiac cycle

  1. Atrial diastole

  2. Atrial systole

  3. Isovolumetric contraction

  4. Ventricular systole

  5. Isovolumetric relaxation
• Cardiac output (CO)


  Amount of blood pumped out by each ventricle in 1 minute, calculated as heart rate (HR) x stroke volume (SV)
• Stroke volume (SV)


  Volume of blood pumped out by a ventricle with each heartbeat
• Normal adult blood volume is about 6,000 ml, so nearly the entire blood supply passes through the body once each minute
• Blood vessels

  • Tunica intima (lines the lumen)
  • Tunica media (middle smooth muscle layer, capable of dilating and constricting)
  • Tunica externa (supports the vessels)
• Cold temperature

  Vasoconstricting effect
• Warm temperature

  Vasodilating effect
• Chemicals/drugs


  Can have widespread effects on blood pressure, e.g. epinephrine increases heart rate and blood pressure
• Important areas to study are fetal circulation and adult circulation
• Atherosclerosis


  Characterized by patchy intimal plaques (atheromas) that encroach on the lumen of medium-sized and large arteries, containing lipids, inflammatory cells, smooth muscle cells, and connective tissue
• Risk factors for atherosclerosis

  • Dyslipidemia
  • Diabetes
  • Cigarette smoking
  • Family history
  • Sedentary lifestyle
  • Obesity
  • Hypertension
• Symptoms of atherosclerosis


  Develop when growth or rupture of the plaque reduces or obstructs blood flow, varying by artery affected
• Diagnosis of atherosclerosis


  Clinical, confirmed by angiography, ultrasonography, or other imaging tests
• Treatment of atherosclerosis

  Includes risk factor, lifestyle, and dietary modification; physical activity; antiplatelet drugs; and antiatherogenic drugs