Heart functioning

Your heart is a remarkable organ and a vital part of your body.

The heart is a strong muscle which pumps blood throughout your body using a system of blood vessels, known as your circulatory system. Blood coming from the heart carries oxygen and food that feeds and nourishes your organs and muscles. Blood returning to the heart is pumped to the lungs to gather more oxygen and food, before making the journey around the body again.

The following animation about how the heart works is from the NZ Heart Foundation (2016).

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Key points

  1. Your heart is positioned in the middle of your chest, it lies in the centre of your circulatory system, this includes all your blood vessels: arteries, capillaries and veins.
  2. Your heart has 4 chambers. Valves to these chambers open and shut like doors to ensure that your blood only goes in one direction, like a one-way street. 
  3. Your heart gets the food and oxygen it requires from its own blood vessel system (the coronary arteries).
  4. A healthy heart delivers just the right amount of blood to your body at just the right pace.

Different jobs for different sides

Your heart has two sides, these are divided by a wall that goes through the centre of your heart, called the septum:

  • The right side of your heart transports blood to your lungs to gather oxygen.
  • The left side of your heart collects the oxygen-filled blood from your lungs and transports it around your body.

Your heart is made up of chambers, valves and muscles:

  • It has four chambers (think of these as rooms) – there are two chambers for each side of the heart.
  • Every chamber has a valve that works just like a traffic light, only letting your blood flow one way, like a one-way street.
  • The sound your heart makes is caused by your heart's valves opening and shutting, a doctor can hear this "lub-DUB" sound using a stethoscope.

What does each chamber do?

  • The atria (AY-tree-uh) – two upper chambers that gather blood as it moves into the heart. Think of these as the ‘front doors’ of the heart. Blood low in oxygen enters first into the right atrium (through the vena cava).
  • Blood moves from the right atrium into the right ventricle.
  • The right ventricle pushes blood toward the lungs (through the pulmonary artery) – here the blood gathers oxygen.
  • Oxygen-loaded blood from the lungs then moves back to the heart (through the pulmonary vein) arriving in the left atrium.
  • This blood then moves from the left atrium to the left ventricle, then it is pushed out to your body (through the aorta).

Transporting blood 

Your heart is linked to your blood vessels (veins, arteries and capillaries):

  • Veins pump blood from your body to your heart.
  • Arteries move blood away from your heart to your body.
  • Capillaries are tiny blood vessels linking your arteries and veins. They deliver oxygen, water, nutrients and wastes between your blood and your body tissues.
  • Your blood vessels are like trains delivering food around your body: your arteries and veins are the trains, your capillaries are the delivery men.

In what order does my blood flow?

  • blood moves from your body into the right side of your heart,
  • then it is pumped back out to your lungs,
  • your oxygen filled blood then re-enters the left side of your heart,
  • finally your oxygen filled blood is transported back out to the rest of your body.

What causes your heart to pump?

Your heart is powered by its own electrical system, this electricity is used to contract and squeeze your heart walls – pumping blood into your circulatory system and around your body.

Learn more

Your heart NZ Heart Foundation, 2014 
Information and resources Heartkids NZ
Heart and diabetes checks NZ Ministry of Health, 2014

Credits: Health Navigator team.