CARDIOVASCULAR SYSTEM - HEART

• Functions of the Cardiovascular System:

  • Regulates blood supply
  • Generates blood pressure
  • Routes blood
  • Ensure 1-way blood flow
• Size of the Heart: Size of a fist and weighs less than 1 lb
• Location of the heart: between lungs in thoracic cavity
• Orientation of the heart: apex (bottom) towards left side
• Pericardium- double-layered sac that anchors and protects heart
• Parietal pericardium - membrane around heart’s cavity
• Visceral pericardium - membrane on heart’s surface
• Pericardial cavity - space around 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
• 4 Chambers:
• Coronary sulcus - separates atria from ventricles
• Atria • Upper portion; Holding chambers • Small, thin walled, contract minimally to push blood into ventricles
• Ventricles • Lower portion; Pumping chambers • Thick, strong walled, contract forcefully to propel blood out of heart
• Interatrial septum - separates right and left atria
• Interventricular septum - separates right and left ventricles
• Valves - structures that ensure 1-way blood flow
• Atrioventricular valves (AV) - between atria and ventricles
• Tricuspid valve - AV valve between RA and RV; 3 cusps
• Bicuspid valve (mitral) - AV valve between LA and LV; 2 cusps
• • Semilunar valves:
  • Pulmonary- base of pulmonary trunk
  • Aortic - base of aorta
  • Chordae tendineae - attached to AV valve flaps ; support valves
• Bicuspid Valve is Open: • Blood flows from LA into LV. • Aortic semilunar valve is closed. • Tension on chordae tendineae is low.
• Bicuspid Valve is Closed? • Blood flows from LV into aorta. • Aortic semilunar valve is open. • Tension on chordae tendineae is high.
• • RIGHT SIDE OF HEART- Pulmonary circuit
  • carries blood from heart to lungs
  • blood is O2 poor, CO2 rich
• Right Atrium - receives blood from 3 places: 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
• Pulmonary trunk - splits into right and left pulmonary arteries
• Pulmonary arteries - carry blood away from heart to lungs
• • LEFT SIDE OF HEART - Systemic circuit:
  • carries blood from heart to body
  • blood is O2 rich, CO2 poor
• Left Atrium - 4 openings (pulmonary veins) that receive blood from lungs
• • Left Ventricle:
  • opens into aorta
  • thicker, contracts more forcefully, higher blood pressure than right ventricle has to get to body
• Aorta - carries blood from Left Ventricle to body
• Coronary arteries: o supply blood to heart wall o originate from base of aorta (above aortic semilunar valve)
• Left coronary artery: o has 3 branches o supply blood to anterior heart wall and left ventricle
• Right coronary artery: o originates on right side of aorta o supply blood to right ventricle