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Circulatory Systems

How the heart, blood and blood vessels deliver oxygen and nutrients to cells and remove carbon dioxide and wastes — plus lymph and blood groups.

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What this chapter covers

  1. Circulatory System and Body Fluids

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    • Circulatory System OverviewDelivers oxygen and nutrients, removes wastes.
    • Body FluidsBlood, tissue fluid and lymph.
    • Vascular SystemsClosed in humans, open in insects.

  2. The Heart

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    • External FeaturesFist-sized, protected by double-layered pericardium.
    • Internal StructureFour chambers, septum and one-way valves.
    • PacemakerSA node initiates each heartbeat.

  3. Blood Vessels

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    • Types of Blood VesselsArteries, veins and capillaries compared.
    • Blood Vessels of the HeartVena cava, pulmonary vessels, aorta, coronary.

  4. Blood Circulation

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    • How the Heart WorksAtria then ventricles contract; valves close.
    • Double CirculationBlood passes through heart twice.

  5. Lymphatic System

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    • Tissue Fluid and Lymph FormationLeaked plasma forms tissue fluid, lymph.
    • Lymphatic OrgansSpleen, tonsils, thymus and lymph nodes.
    • Composition and Functions of LymphMostly lymphocytes; nutritive, drainage, defence roles.

  6. Blood Groups

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    • ABO Blood Group SystemFour groups by RBC surface antigens.
    • Blood Group CompatibilityO universal donor, AB universal recipient.
    • Blood DonationDonated blood stored in blood banks.

  7. Heart-Related Conditions

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    • Palpitations and HypertensionFast heartbeat and high blood pressure.
    • Heart Attack and Cardiac ArrestClot blocks blood; heart stops pumping.
    • Keeping the Heart HealthyLess fat and sugar; regular exercise.

Try a sample question

Which blood group is called the universal donor and why?

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