Cardiovascular system

• The Heart, Blood Vessels, and Blood are the components of the Cardiovascular System
• Heart


  • Regulates blood supply
  • Generates blood pressure
  • Routes blood
  • Ensures 1 way blood flow
• Structures of the Cardiovascular System

  • Carotid artery
  • Jugular vein
  • Aorta
  • Pulmonary trunk
  • Heart
  • Brachial artery
  • Inferior vena cava
  • Femoral artery and vein
• The heart is located between the lungs in the thoracic cavity
• The heart is the size of a fist and weighs less than 1 lb
• The heart is oriented with the apex (bottom) towards the left side
• Pericardium


  Double-layered sac that anchors and protects the heart
• Layers of the Pericardium

  • Parietal pericardium (membrane around heart's cavity)
  • Visceral pericardium (membrane on heart's surface)
  • Pericardial cavity (space around heart)
• Layers of the Heart

  • Epicardium (surface of heart, outside)
  • Myocardium (thick, middle layer composed of cardiac muscle)
  • Endocardium (smooth, inner surface)
• Cardiac Muscle


  • 1 centrally located nucleus
  • Branching cells
  • Rich in mitochondria
  • Striated (actin and myosin)
  • Ca2+ and ATP used for contractions
  • Intercalated disks connect cells
• Chambers of the Heart

  • Left atrium (LA)
  • Right atrium (RA)
  • Left ventricle (LV)
  • Right ventricle (RV)
• The coronary sulcus separates the atria from the ventricles
• Atria


  Upper portion, holding chambers, small and thin walled, contract minimally to push blood into ventricles
• Ventricles


  Lower portion, pumping chambers, thick and strong walled, contract forcefully to propel blood out of heart
• The interventricular septum separates the right and left ventricles
• Valves


  Structures that ensure 1 way blood flow
• Atrioventricular (AV) Valves


  • Tricuspid valve (between RA and RV, 3 cusps)
  • Bicuspid valve (mitral, between LA and LV, 2 cusps)
• Chordae Tendineae


  Attached to AV valve flaps, support the valves
• Semilunar Valves


  • Pulmonary (at base of pulmonary trunk)
  • Aortic (at base of aorta)
• What happens when Bicuspid Valve is Open

  1. Blood flows from LA into LV

  2. Aortic semilunar valve is closed

  3. Tension on chordae tendineae is low
• What happens when Bicuspid Valve is Closed

  1. Blood flows from LV into aorta

  2. Aortic semilunar valve is open

  3. Tension on chordae tendineae is high
• Pulmonary Circuit


  Carries blood from heart to lungs, blood is O2 poor, CO2 rich
• Right Atrium


  Receives blood from superior and inferior vena cava, and coronary sinus
• Superior Vena Cava


  Drains blood above diaphragm (head, neck, thorax, upper limbs)
• Inferior Vena Cava


  Drains blood below diaphragm (abdominopelvic cavity and lower limbs)
• Coronary Sinus


  Drains blood from myocardium
• Right Ventricle


  Opens into pulmonary trunk, which splits into right and left pulmonary arteries
• Systemic Circuit


  Carries blood from heart to body, blood is O2 rich, CO2 poor
• Left Atrium


  Has 4 openings (pulmonary veins) that receive blood from lungs
• Left Ventricle


  Opens into aorta, thicker and contracts more forcefully, higher blood pressure than right ventricle to get to body
• Aorta


  Carries blood from LV to body
• Blood Flow through Heart

  1. RA

  2. Tricuspid valve

  3. RV

  4. Pulmonary semilunar valve

  5. Pulmonary trunk

  6. Pulmonary arteries

  7. Lungs

  8. Pulmonary veins

  9. LA

  10. Bicuspid valve

  11. LV

  12. Aortic semilunar valve

  13. Aorta

  14. Body
• Coronary Arteries


  Supply blood to heart wall, originate from base of aorta (above aortic semilunar valve)
• Left Coronary Artery


  Has 3 branches, supplies blood to anterior heart wall and left ventricle
• Right Coronary Artery


  Originates on right side of aorta, supplies blood to right ventricle
• Pacemaker Potential


  Changes in membrane channels' permeability are responsible for producing action potentials
• Phases of Cardiac Action Potential

  1. Depolarization (Na+ channels open, Ca2+ channels open)

  2. Plateau (Na+ channels close, some K+ channels open, Ca2+ channels remain open)

  3. Repolarization (K+ channels open, Ca2+ channels close)
• Plateau phase prolongs action potential by keeping Ca2+ channels open
• In cardiac muscle, action potentials take 200-500 msec, compared to 2 msec in skeletal muscle
• Sinoatrial (SA) Node


  In RA, where action potential originates, functions as pacemaker, has large number of Ca2+ channels