Class 10 Computer Science Chapter 1: Office Tools (Notes & Online Test) - PSEB

BODY FLUIDS AND CIRCULATION

NCERT Masterclass & NEET Biology Study Module

1. Blood and Its Composition

Blood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.

• Plasma (55%): Straw coloured, viscous fluid. Water is 90-92%. Proteins are 6-8% (Fibrinogen for clotting, Globulins for defense/immunity, Albumins for osmotic balance). Serum = Plasma - Clotting factors.
• Formed Elements (45%):
  • Erythrocytes (RBCs): Most abundant (5-5.5 million/$mm^3$). Biconcave, devoid of nucleus in mammals. Contain 12-16 g of Haemoglobin per 100 ml. Lifespan is 120 days. Destroyed in the Spleen (Graveyard of RBCs).
  • Leucocytes (WBCs): Nucleated, 6000-8000/$mm^3$.
    Granulocytes: Neutrophils (60-65%, phagocytic), Eosinophils (2-3%, allergic reactions), Basophils (0.5-1%, secrete histamine, serotonin, heparin).
    Agranulocytes: Lymphocytes (20-25%, B & T cells for immunity), Monocytes (6-8%, phagocytic).
  • Platelets (Thrombocytes): Cell fragments from megakaryocytes (1.5 - 3.5 lakh/$mm^3$). Essential for blood clotting.

2. Blood Groups & Coagulation

🔥 ABO and Rh Grouping:

• ABO Grouping: Based on presence/absence of two surface antigens (A and B) on RBCs. Blood Group O has no antigens (Universal Donor). Blood Group AB has no antibodies in plasma (Universal Recipient).
• Erythroblastosis foetalis: Occurs when an Rh-negative mother carries an Rh-positive foetus. During the first pregnancy, mixing of blood at birth causes the mother to form anti-Rh antibodies. In subsequent Rh+ pregnancies, these antibodies cross the placenta and destroy foetal RBCs. Prevented by administering anti-Rh antibodies (RhoGAM) to the mother immediately after the first delivery.

Coagulation of Blood: A cascade process. Injured tissues/platelets release Thrombokinase $\rightarrow$ converts inactive Prothrombin into Thrombin $\rightarrow$ Thrombin converts soluble Fibrinogen into insoluble Fibrin. Calcium ions ($Ca^{++}$) play a very important role in clotting.

3. Circulatory Pathways & Human Heart Anatomy

Heart Chambers in Vertebrates: Fishes (2-chambered, single circulation), Amphibians & Reptiles (3-chambered, incomplete double circulation - except crocodiles), Birds & Mammals (4-chambered, double circulation).

Human Heart: Mesodermally derived, situated in thoracic cavity, protected by double-walled Pericardium.

• Valves: Tricuspid valve (Right atrium-ventricle), Bicuspid/Mitral valve (Left atrium-ventricle), Semilunar valves (opening of right/left ventricles into pulmonary artery/aorta).
• Nodal Tissue: Heart is autoexcitable (myogenic).
  - SAN (Sino-Atrial Node): Upper right corner of right atrium. Acts as the Pacemaker (generates 70-75 action potentials/min).
  - AVN (Atrio-Ventricular Node): Lower left corner of right atrium.
  - Purkinje Fibres: Minute fibres distributed throughout the ventricular musculature.

4. Cardiac Cycle & ECG

Cardiac Output = Stroke Volume $\times$ Heart Rate
Cardiac Output = $70 \text{ ml} \times 72 \text{ beats/min} \approx 5000 \text{ ml}$ (5 Litres/min).

Heart Sounds: First sound (Lub) is due to closure of tricuspid and bicuspid valves. Second sound (Dub) is due to closure of semilunar valves.

5. Double Circulation & Regulation

Double Circulation: Includes Pulmonary circulation (Right Ventricle $\rightarrow$ Lungs $\rightarrow$ Left Atrium) and Systemic circulation (Left Ventricle $\rightarrow$ Body $\rightarrow$ Right Atrium). This ensures oxygenated and deoxygenated blood do not mix.

Hepatic Portal System: A unique vascular connection between the digestive tract and liver. The hepatic portal vein carries blood from intestine to the liver before it is delivered to the systemic circulation.

Regulation of Cardiac Activity: Normal activities are regulated intrinsically (auto-regulated by nodal tissues).
- Medulla oblongata can moderate cardiac function through the Autonomic Nervous System (ANS).
- Sympathetic nerves: Increase heart rate and strength of contraction (increases cardiac output).
- Parasympathetic nerves: Decrease heart rate (decreases cardiac output). Adrenal medullary hormones also increase cardiac output.

6. Disorders of Circulatory System

• Hypertension (High Blood Pressure): Blood pressure higher than normal (120/80). A persistent BP of 140/90 or higher shows hypertension. It affects vital organs like brain and kidney.
• Coronary Artery Disease (CAD) / Atherosclerosis: Deposition of calcium, fat, cholesterol, and fibrous tissue in coronary arteries, making the lumen narrower and reducing blood supply to heart muscle.
• Angina (Angina Pectoris): A symptom of acute chest pain appears when no enough oxygen is reaching the heart muscle. Can occur in men and women of any age but common in middle-aged and elderly.
• Heart Failure: State of heart when it is not pumping blood effectively enough to meet the needs of the body. Often called congestive heart failure because congestion of the lungs is a main symptom. (Not the same as Cardiac Arrest - where heart stops beating, or Heart Attack - where heart muscle is suddenly damaged by inadequate blood supply).

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🚀 NEET CIRCULATION MEGA QUIZ (100 MCQ)

Solve the 5 parts below to master Blood Composition, Cardiac Cycle, ECG, and Disorders.

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