Heart And Vascular

• Heart


  Hollow muscular organ located in the mediastinum, weighs about 255-310g, base is the upper portion at the left 2nd ICS, apex is the lower portion at the 5th ICS LMCL, RA and RV are closer to the chest

  
• Artery


  • Carries deoxygenated blood to the lungs
• Veins


  • Carry oxygenated blood to the left atrium
• Heart Valves


  • Tricuspid valve (3 cusps, between RA and LV)
  • Bicuspid (mitral) valve (2 cusps, between LA and LV)
  • Aortic semilunar valve (at the beginning of the ascending aorta as it exits the left ventricle)
  • Pulmonary semilunar valve (at the entrance of the pulmonary artery as it exits the right ventricle)
• Aortic semilunar valve and Pulmonary semilunar valve


  • Open during ventricular contraction and close from the pressure of blood when the ventricles relax
• Collagen fibers


  • Also called chordae tendineae, anchor the AV valve flaps to papillary muscles within the ventricles
• Layers of the Heart

  • Epicardium (outer surface)
  • Pericardium (tough, inextensible, loose-fitting, fibroserous sac that attaches to the great vessels and surrounds the heart)
  • Parietal pericardium (secretes a small amount of pericardial fluid that allows for smooth, friction-free movement of the heart)
  • Myocardium (thickest layer, made up of contractile cardiac muscle cells)
  • Endocardium (thin layer of endothelial tissue that forms the innermost layer and is continuous with the endothelial lining of blood vessels)

  
• Sinoatrial node


  • Generates impulses (at a rate of 60-100/min) that are conducted over both atria, causing them to contract simultaneously and send blood into the ventricles; "pacemaker of the heart"
• The right ventricle pumps oxygen-poor blood to the lungs via the pulmonary trunk.
• Papillary muscles


  Finger-like projections that extend from the walls of the ventricles and are connected to the AV valve flaps via the collagen fibers. Papillary muscles help to prevent the valve flaps from prolapsing during ventricular contraction.
• Heart


  Hollow muscular organ located in the mediastinum, weighs about 255-310g
• Heart


  • Base - upper portion; left 2nd ICS
  • Apex - lower portion; 5th ICS LMCL
  • RA and RV - closer to the chest
• Artery


  Carrying deoxygenated blood to the lungs
• Veins


  Carrying oxygenated blood to the left atrium
• Heart Valves

  • Tricuspid valve - composed of three cusps, located between the RA and LV
  • Bicuspid (mitral) valve - composed of two cusps, located between the LA and LV
  • Aortic semilunar valve - located at the beginning of the ascending aorta as it exits the left ventricle
  • Pulmonary semilunar valve - located at the entrance of the pulmonary artery as it exits the right ventricle
• Aortic semilunar valve and Pulmonary semilunar valve


  Open during ventricular contraction and close from the pressure of blood when the ventricles relax
• Collagen fibers


  Also called chordae tendineae, anchor the AV valve flaps to papillary muscles within the ventricles
• Epicardium


  • Outer surface of the heart
• Pericardium


  • Tough, inextensible, loose-fitting, fibroserous sac that attaches to the great vessels and surrounds the heart
  • Parietal pericardium - secretes a small amount of pericardial fluid that allows for smooth, friction-free movement of the heart
• Myocardium


  • Thickest layer of the heart, made up of contractile cardiac muscle cells
• Endocardium


  • Thin layer of endothelial tissue that forms the innermost layer of the heart and is continuous with the endothelial lining of blood vessels
• Sinoatrial node


  Generates impulses (at a rate of 60-100/min) that are conducted over both atria, causing them to contract simultaneously and send blood into the ventricles
• Atrioventricular node


  Slightly delays incoming electrical impulses from the atria and the relays the impulse to the AV bundle in the upper interventricular septum
• Atrioventricular bundle (Bundle of His)


  Inherent discharge of 40-60/min
• Electrocardiogram (ECG) records only the electrical activities of the heart

  
• P wave


  Corresponds to depolarization of the atria (SA node)
• QRS wave


  Corresponds to ventricular depolarization
• T wave


  Corresponds to ventricular repolarization
• Atrial repolarization record is masked by the larger QRS complex
• Based on the magnitude of the ECG waves and the time between waves, ECGs can be used to diagnose heart abnormalities

  
• Cardiac cycle


  • Filling and emptying of the heart's chamber
  • Repetitive contraction and relaxation of the heart chambers
• Heart sounds


  • "Lub dubb" - produced by valve closure
  • S1 (lub) - closure of AV valves, correlates beginning of systole
  • S2 (dubb) - closure of SL valve, correlates beginning of diastole
  • S3 - ventricular gallop, heard early in diastole
  • S4 - atrial gallop, heard late in diastole
• Murmurs


  Pathologic heart sounds produced when blood is pumped across a heart valve and creates a blowing or swishing sound heard across precordium
• Conditions that contribute to turbulent blood flow

  • Increased blood velocity
  • Structural valve defects
  • Valve malfunction
  • Abnormal chamber openings (septal defects)
• Cardiac output

  Volume of blood pumped by the ventricles within 1 minute
• Stroke volume


  Amount of blood pumped from L ventricle with each contraction, ~70 ml
• Preload


  Amount of blood inside the ventricles before the contraction of ventricles
• Afterload


  Pressure that must be overcome by the left ventricles in order to pump out blood towards the aorta
• Factors affecting stroke volume


  • Preload
  • Afterload
  • Synergy contraction
  • Compliance of distensibility of the ventricles
  • Contractility of myocardium
  • ANS stimulation (sympathetic and parasympathetic)
• Carotid artery pulse


  Common carotid arteries located between trachea and SCM, centrally located arterial pulse