🩸 Blood Physiology (NCERT Summary)
🔷 What is Blood?
Blood is a fluid connective tissue that transports substances like gases, nutrients, hormones, and waste products throughout the body.
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🔹 Components of Blood
1. Plasma (55% of blood):
Straw-colored liquid.
Contains water (90-92%), proteins (albumin, globulin, fibrinogen), glucose, amino acids, salts, hormones, waste, etc.
2. Formed Elements (45% of blood):
RBCs (Erythrocytes):
Biconcave, no nucleus in mammals.
Contain hemoglobin (oxygen-carrying pigment).
Lifespan: ~120 days.
WBCs (Leukocytes):
Nucleated, defend against infections.
Types:
Granulocytes: Neutrophils, Eosinophils, Basophils.
Agranulocytes: Lymphocytes, Monocytes.
Platelets (Thrombocytes):
Cell fragments, help in blood clotting.
Lifespan: ~7 days.
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🔹 Functions of Blood
Transport: Oxygen, CO₂, nutrients, hormones, waste.
Regulation: Body temperature, pH, water balance.
Protection: Immune defense (WBCs), clotting (platelets & fibrinogen).
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🔹 Blood Groups (ABO System)
Determined by antigens (A, B) on RBCs.
Types: A, B, AB (universal recipient), O (universal donor).
Rh Factor: Another antigen (Rh⁺ or Rh⁻).
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🔹 Blood Clotting
A protective mechanism to stop bleeding.
Platelets release thromboplastin → Prothrombin → Thrombin
Thrombin converts fibrinogen to fibrin, forming a clot.
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🔹 Disorders Related to Blood
Anemia: Low hemoglobin.
Leukemia: Cancer of WBCs.
Hemophilia: Clotting disorder.
Thalassemia: Genetic hemoglobin defect.
