Final

• Coronary Circulation


  Blood supply to heart muscle
• Coronary Circulation


  • 85% flow into left Coronary artery (widow maker)
  • 10% flow into Right coronary artery
• 70% of Coronary blood flow occurs when ventricles are relaxed and SLV are shut
• Angina pectoris


  Pain Associated with decreased oxygen in heart muscle
• Myocardial Infarction


  Death of heart cells (heart attack)-Cut off too long
• When oxygen decreases in local vessels

  1. Blood vessels dilate

  2. Brings more blood to the area that needs the oxygen
• Cardiac output


  Equal to the stroke volume times the heart rate, Cardiac output should be the same for the right and left ventricles
• Normal Heart capacity


  • 145mL
  • The end diastolic volume minus the stroke volume will tell you how much blood remains in the heart
• Frank-Starling Law of the heart

  If stretch muscle (increased venous return in exercise) - Cause increased force of contraction
• Increasing Stroke Volume


  • Up to 2x (70 to 140 mL)
• Increasing Heart Rate


  • Up to 2.5x (70 to 180 bpm)
• Mean Arterial Pressure (MAP)

  The sum of the diastolic pressure plus one-third of the difference between the systolic and diastolic pressures (drives the blood)
• Autonomic nervous system dynamically adjusts cardiac output and MAP
• Hemorrhage - Blood loss


  Causes a reduction in MAP
• If left untreated, hemorrhage results in rapid and irreversible damage to the brain and heart
• Cardiac Failure


  Inadequate return of blood to the heart (hemorrhage, peripheral pooling shock)
• Congestive Heart Failure


  If ventricles unable to pump blood there will be a backup of blood in the veins to the heart
• Korotkoff sounds


  • Heard when blood pressure cuff is deflated
  • 1st sound-systolic BP
  • 2nd sound-diastolic BP
• Arterial Pressure reduces as blood travels from large arteries to small
• Too much pressure will damage capillary beds
• Cardiovascular characteristics


  • oxygen
  • Nutrients
  • wastes
  • Hormones
• Cardiovascular system


  • Flow: Depends on ability of heart to pump
  • Cardiac output: Amount of blood pumped per minute
• Heart


  • Size: Adult fist (300g)
  • Pump rate: 60-70 bpm
  • Volume: 70ml per beat
• Cardiac Cycle


  1. Systole - contraction of heart chamber

  2. Diastole - relaxation of heart chamber

  3. Sequence of events: Ventricle systole, ventricle diastole, atrial systole, atrial diastole
• When atria are in systole the ventricles are in diastole
• Arteries stretch during systole
• Atrioventricular valves (AV)


  • Tricuspid
  • Bicuspid (Mitral)
• Semilunar valves


  • Aortic
  • Pulmonic
• Chordae tendineae


  Prevents eversion of AV valves
• Papillary muscle


  Prevents eversion of AV valves
• AV valves are closed during ventricular systole, open during ventricular diastole

  Semilunar valves are open during ventricular systole, closed during ventricular diastole
• The heart is never completely empty
• Phases/periods of ventricles (left)

  1. Rapid filling phase

  2. Rapid ejection phase

  3. Isovolumetric relaxation
• Heart sounds


  First sound (lub) - Closing of AV valves

  Second sound (dub) - Closing of semilunar valves
• Murmur


  Backflow or turbulent blood flow caused by leaky valve
• Intercalated disks


  Allow electrical conduction from one cell to another, making the heart a syncytium
• Calcium entry into cardiac cells

  Occurs after sodium entry, prevents tetany contraction
• Dicrotic notch is a measurement artifact caused by pressure increase in aorta when aortic semilunar valve shuts
• Sinoatrial (SA) node


  Acts as the pacemaker of the heart
• Pulmonary hypertension decreases the second heart sound

  Mitral valve prolapse causes a plateau event for depolarization