Heart Structure and Function

Heart Structure and Function

Heart Structure

  • The heart is a muscular organ positioned in the chest, slightly to the left of the centre.
  • It is roughly the size of a fist and functions to pump blood around the body.
  • The heart is divided into two sides: left and right, which are further divided into upper and lower sections, each called atria and ventricles respectively.

Chambers of the Heart

  • The atria are the two upper chambers that receive blood entering the heart.
  • On the left of the heart, the left atrium receives oxygenated blood from the lungs via the pulmonary veins.
  • On the right, the right atrium receives deoxygenated blood from the body through the superior and inferior vena cava.
  • The ventricles are the two lower chambers responsible for pumping blood out of the heart.
  • The left ventricle pumps oxygenated blood to the rest of the body through the aorta.
  • The right ventricle pumps deoxygenated blood to the lungs through the pulmonary artery.

Valves of the Heart

  • Heart valves ensure one-way blood flow through the heart.
  • Two main types exist: atrioventricular valves (AV valves) and semilunar valves.
  • AV valves are located between atria and ventricles, controlling blood flow from atria to ventricles.
  • The mitral valve separates the left atrium and left ventricle; the tricuspid valve does the same on the right.
  • Semilunar valves regulate blood flow from ventricles to arteries. The aortic valve connects the left ventricle to the aorta, and the pulmonary valve connects the right ventricle to the pulmonary artery.

Function of the Heart

  • The heart’s main function is to pump blood around the body, supplying oxygen, nutrients, and hormones to cells and removing waste products like carbon dioxide.
  • Each heartbeat results from a systematic chain of events known as the cardiac cycle consisting of two phases: diastole and systole.
  • During diastole, the heart relaxes, allowing the chambers to fill with blood.
  • During systole, the heart contracts, forcing blood out of the heart and into the circulatory system.
  • This entire process is governed by electrical signals from the heart’s natural pacemaker, the sinoatrial node (SA node) located in the right atrium.

Keep in mind: The heart – a marvellous organ beating tirelessly to circulate blood and sustain life!