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The Human Body: Circulatory System - Blood and its components

Grade 5ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Blood is a red-colored fluid connective tissue that circulates throughout the body in a closed system of tubes called blood vessels.

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Plasma: The liquid part of the blood, which is straw-colored and constitutes about 55%55\% of the total blood volume. It is composed of approximately 90−92%90-92\% water and contains dissolved nutrients, salts, and waste products.

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Red Blood Cells (RBCs) or Erythrocytes: These are disc-shaped cells that contain a red pigment called Hemoglobin (HbHb). Hemoglobin binds with Oxygen (O2O_2) to form Oxyhemoglobin (HbO2HbO_2) for transport to body cells.

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White Blood Cells (WBCs) or Leukocytes: These cells act as the body's defense system. They are larger than RBCs but fewer in number and help fight infections by destroying germs.

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Platelets or Thrombocytes: These are tiny, colorless cell fragments that help in the clotting of blood at the site of an injury to prevent excessive blood loss.

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Functions of Blood: It transports oxygen, nutrients, and hormones; it carries carbon dioxide (CO2CO_2) and other waste products to excretory organs; and it helps maintain body temperature.

📐Formulae

Total Blood=Plasma (≈55%)+Blood Cells (≈45%)Total \ Blood = Plasma \ (\approx 55\%) + Blood \ Cells \ (\approx 45\%)

Hemoglobin (Hb)+Oxygen (O2)→Oxyhemoglobin (HbO2)Hemoglobin \ (Hb) + Oxygen \ (O_2) \rightarrow Oxyhemoglobin \ (HbO_2)

RBC<WBC<Platelets (Size Comparison)RBC < WBC < Platelets \text{ (Size Comparison)}

RBC>Platelets>WBC (Numerical Abundance Comparison)RBC > Platelets > WBC \text{ (Numerical Abundance Comparison)}

💡Examples

Problem 1:

If a person is diagnosed with Anemia, which component of the blood or specific molecule is likely deficient, and what is its chemical symbol?

Solution:

The person is likely deficient in Hemoglobin, represented as HbHb.

Explanation:

Anemia is a condition where the blood lacks enough healthy red blood cells or hemoglobin. Since hemoglobin (HbHb) is responsible for carrying O2O_2, its deficiency leads to tiredness and weakness.

Problem 2:

During a laboratory test, a scientist observes that a blood sample contains 91%91\% water in its liquid matrix. What is this liquid matrix called?

Solution:

Plasma

Explanation:

Plasma is the fluid component of blood. It consists of roughly 90%90\% to 92%92\% water, with the remaining 8−10%8-10\% consisting of proteins, glucose, mineral ions, and hormones.

Problem 3:

Why is blood clotting important when you get a cut?

Solution:

To prevent the loss of blood from the body.

Explanation:

Platelets aggregate at the site of injury to form a clot. This process prevents the continuous flow of blood (Blood Loss→0Blood \ Loss \rightarrow 0) and blocks the entry of pathogens into the circulatory system.