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What's In Blood?

    What's In Blood?

    Have you ever seen a picture of blood or seen a blood sample under a microscope? It’s quite fascinating! Blood is an important component of our cardiovascular system that takes care of transporting nutrients and oxygen, and eliminating toxins from our body. Learn more about blood here.

    Picture of Blood: What Makes Up Blood?

    The average human has roughly 5 liters (more than a gallon) of blood, which is continuously circulating throughout the body. It delivers nutrients and oxygen to our cells and takes care of waste elimination.

    Blood is primarily liquid with various cells and proteins suspended in it, making blood “thicker” than pure water. About half of blood is made up of a fluid called plasma, which also contains glucose and other dissolved nutrients.

    The following types of blood cells make up around half of the volume of blood.

    • Red blood cells transport oxygen to tissues.
    • White blood cells help the body fight illnesses.
    • Platelets are tiny cells that aid in blood clotting.

    If you recall those posters in school or the picture of blood in your textbook, you’ll remember that blood flows through your circulatory system. Blood travels via arteries and veins, where it is kept from clotting by the smoothness of the vessels and a delicately balanced ratio of clotting factors.

    Common Blood Disorders and Conditions

    What are some common blood disorders and conditions? Check out the list here.

    Hemorrhage (bleeding)

    Internal bleeding (such as into the bowels or after a vehicle accident) may not be immediately apparent, but blood spilling out of blood vessels may be obvious, as from a wound reaching the skin.


    Hematomas are collections of blood that form within human tissues as a result of internal bleeding.


    White blood cells multiply improperly and circulate through the blood in leukemia, a kind of blood cancer, making patients vulnerable to infections.


    Anemia, kidney failure, and elevated blood calcium levels are symptoms of multiple myeloma, a kind of blood malignancy of plasma cells comparable to leukemia.


    White blood cells inappropriately multiply inside lymph nodes and other tissues in lymphoma, a type of blood cancer that can eventually lead to organ failure by expanding the tissues and disrupting blood flow.


    Anemia is a condition where there are unusually few red blood cells in the blood, which can lead to exhaustion and shortness of breath. However, it frequently goes undetected. There are many types of anemia, like Iron Deficiency Anemia and Thalassemia. Learn more about anemia here:


    Hemolysis, or hemolytic anemia, is anemia brought on by the rapid bursting of huge numbers of red blood cells. Immune system dysfunction is one of the causes.


    High amounts of iron in the blood and iron deposits in the liver, pancreas, and other organs are all symptoms of hemochromatosis.


    Blood infections, such as bacteremia, are dangerous and may call for hospitalization as well as ongoing antibiotic infusions.


    Malaria is an infection of the red blood cells by the parasite plasmodium, which is spread by mosquitoes. It results in sporadic fevers, chills, and may even cause organ damage.


    This condition manifests as abnormally low levels of platelets in the blood, which can cause bleeding in extreme cases.


    This is characterized by abnormally low levels of white blood cells in the blood, which makes it difficult to fight infections.


    Disseminated intravascular coagulation (DIC) is an unregulated process that causes bleeding and clotting to occur simultaneously in very small blood capillaries.


    Hemophilia is an inherited (genetic) weakness of specific blood clotting proteins that can lead to excessive or uncontrolled bleeding.


    Having an excessively high amount of red blood cells, or polycythemia, can be caused by low blood oxygen levels or a condition that resembles cancer.


    A blood clot in a deep vein, generally in the leg, is known as a deep vein thrombosis (DVT). DVTs are risky because they could become dislodged and go to the lungs, where they would cause a pulmonary embolism.

    Learn more about Heart Health here.

    Hello Health Group does not provide medical advice, diagnosis or treatment.

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    Written by Hello Doctor Medical Panel Updated 2 weeks agoMedically reviewed by Lauren Labrador, MD, FPCP, DPCC
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