Heart Function and Circulation

Heart Function

• The heart is a muscular organ that pumps blood throughout the body.
• It has four chambers: left and right atria, and left and right ventricles.
• The heart beats around 100,000 times per day, pumping around 2,000 gallons of blood.
• The heart's primary function is to pump oxygenated blood to the body and deoxygenated blood to the lungs.
• The heartbeat is regulated by the sinoatrial (SA) node, which acts as the heart's natural pacemaker.

Circulatory Pathways

• Pulmonary Circulation:
  • Deoxygenated blood from the body enters the right atrium.
  • Blood flows through the tricuspid valve into the right ventricle.
  • Blood is pumped through the pulmonary valve into the pulmonary artery, which takes it to the lungs.
  • Oxygenated blood from the lungs returns to the heart through the pulmonary veins.
• Systemic Circulation:
  • Oxygenated blood from the lungs enters the left atrium.
  • Blood flows through the mitral valve into the left ventricle.
  • Blood is pumped through the aortic valve into the aorta, which distributes it to the rest of the body.
  • Deoxygenated blood from the body returns to the heart through the superior and inferior vena cava.

Blood Pressure

• Blood pressure is the force exerted by blood on the walls of blood vessels.
• It is measured in millimeters of mercury (mmHg) and is typically expressed as a ratio of systolic pressure to diastolic pressure (e.g., 120/80 mmHg).
• Systolic Pressure:
  • The highest pressure in the blood vessels, occurring when the heart beats.
  • Average systolic pressure is around 120 mmHg.
• Diastolic Pressure:
  • The lowest pressure in the blood vessels, occurring when the heart is at rest.
  • Average diastolic pressure is around 80 mmHg.
• Factors Affecting Blood Pressure:
  • Cardiac output
  • Peripheral resistance
  • Blood volume
  • Vessel elasticity and diameter