Human Body: Circulatory System — Flashcards

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The circulatory system is the body's transport system that carries oxygen, nutrients, hormones, and waste products using blood. It consists of the heart, blood, and blood vessels. It helps maintain bo…

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The three main parts are: (1) Heart – the pump, (2) Blood – the transport medium, and (3) Blood vessels – the pathways (arteries, veins, capillaries). Together, they ensure continuous blood flow throu…

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Blood has two main parts: (1) Plasma – the yellowish liquid (90% water) carrying nutrients, hormones, and waste, and (2) Blood cells – red blood cells (RBCs), white blood cells (WBCs), and platelets.

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Blood is red due to haemoglobin, a protein in red blood cells that contains iron. Haemoglobin binds with oxygen in the lungs and gives blood its red color. More oxygen means bright red; less oxygen ma…

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RBCs carry oxygen from the lungs to all body cells and bring back carbon dioxide to the lungs for exhalation. They contain haemoglobin, which binds oxygen. Mature RBCs have no nucleus, allowing more s…

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WBCs protect the body from infections and diseases. They fight germs in two ways: (1) by surrounding and digesting harmful bacteria (phagocytosis), and (2) by producing antibodies that destroy pathoge…

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Platelets help in blood clotting when we get a cut. They gather at the wound site and form a plug to stop bleeding. Without platelets, even small injuries could cause dangerous blood loss. Low platele…

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Low platelet count (e.g., in dengue fever) can cause excessive bleeding, bruising, and difficulty in clotting. In severe cases, it can be life-threatening. Normal count is 1.5–4.5 lakh/mm³; below 50,0…