What Is the Circulatory System? 3 Main Parts & Their Functions


The circulatory system

The blood circulatory system (cardiovascular system) delivers nutrients and oxygen to the cells in the body and removes waste products.

The main roles of the blood circulatory system (cardiovascular system) are to deliver nutrients and oxygen to the cells in the body and to have the waste products removed.

The heart and the blood vessels (arteries, veins, and capillaries) of the circulatory system go through the entire body to provide the cells with the nutrients and oxygen they need.

What Are Parts of the Circulatory System?

There are many parts of the circulatory system which all work together to keep the body’s cells functioning.

  • Blood
    • Red blood cells carry oxygen
    • White blood cells are part of the immune system
    • Platelets are needed for clotting
    • Plasma helps the body distribute nutrients and remove waste
  • The heart
    • Sits inside the chest slightly to the left, in front of the lungs, and pumps blood around the body
    • It has four chambers that contract, and valves that make the sound of the heartbeats
      • The right upper chamber (atrium) takes in deoxygenated blood full of carbon dioxide
      • The blood is squeezed down into the right lower chamber (ventricle) and travels through an artery to the lungs where carbon dioxide is replaced with oxygen
      • The oxygenated blood travels back to the heart, entering the left upper chamber (atrium)
      • It is then pumped into the left lower chamber (ventricle) and then into an artery called the aorta where the blood travels throughout the body again
  • Blood vessels
    • Arteries
      • They are muscular and pump oxygenated blood from the heart
      • The largest artery is the aorta, which connects to the heart and takes in oxygenated blood from the left ventricle
    • Capillaries
      • The smallest blood vessel; so small blood cells can only move through them one at a time
      • Oxygen and food nutrients move through capillaries to the cells
      • Capillaries also connect to veins, so wastes from cells can be picked up by the blood
    • Veins
      • Have one-way valves instead of muscles, so blood doesn’t go the wrong way
      • They carry deoxygenated blood from the body to the heart, where it can be sent to the lungs
      • One exception is the network of pulmonary veins, which take oxygenated blood from the lungs to the heart

Reviewed on 8/24/2022


Image source: iStock Images
https://www.ncbi.nlm.nih.gov/books/NBK279250/ https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/circulatory-system


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