Full Chapter Summary & Detailed Notes - Body Fluids and Circulation Class 11 NCERT
Overview & Key Concepts
- Chapter Goal: Understand transport mechanisms in animals, focusing on blood, lymph, heart structure, circulation pathways, cardiac regulation, and disorders. Exam Focus: Blood composition, ABO/Rh grouping, cardiac cycle, double circulation. 2025 Updates: Emphasis on cardiovascular health and evolutionary adaptations. Fun Fact: Human heart beats ~100,000 times/day, pumping 5L blood/minute. Core Idea: Efficient transport of nutrients/O2 and waste removal is vital for multicellular life. Real-World: Links to hypertension, heart failure prevention.
- Wider Scope: Foundation for human physiology, links to respiration, excretion, and evolutionary biology.
15.1 Blood
Blood is a special connective tissue with plasma (fluid matrix) and formed elements. It transports nutrients, O2, wastes, and defends against pathogens.
- 15.1.1 Plasma: Straw-colored, viscous (55% blood). 90-92% water; 6-8% proteins (fibrinogen for clotting, globulins for defense, albumins for osmotic balance). Minerals (Na+, Ca2+, etc.), glucose, amino acids, lipids in transit. Clotting factors present; without them, it's serum.
- 15.1.2 Formed Elements: 45% blood. RBCs (erythrocytes): 5-5.5 million/mm³, biconcave, nucleated in non-mammals, hemoglobin (12-16g/100ml) for gas transport, 120-day lifespan, destroyed in spleen. WBCs (leucocytes): 6000-8000/mm³, colorless, nucleated. Granulocytes: Neutrophils (60-65%, phagocytic), Eosinophils (2-3%, allergies/infections), Basophils (0.5-1%, inflammation via histamine). Agranulocytes: Lymphocytes (20-25%, B/T for immunity), Monocytes (6-8%, phagocytic). Platelets (thrombocytes): 1.5-3.5 lakh/mm³, from megakaryocytes, for clotting.
- 15.1.3 Blood Groups: ABO: Antigens A/B on RBCs, antibodies in plasma. A (anti-B), B (anti-A), AB (none, universal recipient), O (anti-A+B, universal donor). Rh: 80% Rh+ (antigen present); Rh- forms antibodies if exposed. Incompatibility in pregnancy (Rh- mother, Rh+ fetus) causes erythroblastosis foetalis; prevented by anti-Rh antibodies post-first delivery.
- 15.1.4 Coagulation: Clotting prevents blood loss. Injury activates platelets/tissues → thrombokinase → prothrombin → thrombin → fibrinogen → fibrin (clot mesh). Ca2+ essential. Cascade of inactive factors.
15.2 Lymph (Tissue Fluid)
Interstitial fluid from capillaries (water, solutes out; proteins/RBCs in vessels). Same minerals as plasma; exchanges nutrients/gases with cells. Lymphatic system drains back to veins. Lymph: Colorless, lymphocytes for immunity, carries nutrients/hormones/fats (via lacteals in intestines).
15.3 Circulatory Pathways
Open (arthropods/molluscs: blood in sinuses); Closed (annelids/chordates: vessels for regulation). Vertebrates: 2-chambered (fish, single circulation), 3-chambered (amphibians/reptiles except crocs, incomplete double), 4-chambered (crocs/birds/mammals, complete double).
- 15.3.1 Human Circulatory System: Heart (mesodermal, thoracic cavity, fist-sized, pericardium-protected), 4 chambers (2 atria upper, 2 ventricles lower). Septa: Inter-atrial (thin), inter-ventricular (thick). Valves: Tricuspid (right AV), bicuspid/mitral (left AV), semilunar (pulmonary/aorta). Nodal tissue: SAN (pacemaker, 70-75/min), AVN, AV bundle (His), Purkinje fibers (autoexcitable).
- 15.3.2 Cardiac Cycle: 0.8s cycle (72/min). Joint diastole → atrial systole (30% ventricular fill) → ventricular systole (closure AV valves = lub; semilunar open, blood to lungs/aorta) → ventricular diastole (semilunar close = dub; AV open). Stroke volume: 70ml; cardiac output: 5L/min (SV × HR).
- 15.3.3 Electrocardiogram (ECG): Graphical electrical activity. P-wave (atrial depolarization), QRS (ventricular depolarization/systole start), T-wave (ventricular repolarization). Leads monitor; deviations indicate abnormalities.
15.4 Double Circulation
Blood vessels: 3 layers (tunica intima endothelium, media smooth muscle/elastic, externa fibrous). Pulmonary: RV → lungs (deoxygenated) → LA (oxygenated). Systemic: LV → aorta → tissues → vena cava → RA. Hepatic portal: Intestine → liver. Coronary: Heart muscle supply.
15.5 Regulation of Cardiac Activity
Myogenic (intrinsic nodal tissue). Neural: Sympathetic (↑ HR/force/output), parasympathetic (↓). Hormonal: Adrenaline ↑ output. Medulla oblongata center moderates via ANS.
15.6 Disorders of Circulatory System
- Hypertension: >140/90 mmHg; risks heart/brain/kidney damage.
- CAD/Atherosclerosis: Calcium/fat/cholesterol deposits narrow arteries.
- Angina: Chest pain from O2 shortage to heart.
- Heart Failure: Ineffective pumping; congestion symptoms (not arrest/attack).
Summary
Vertebrates use blood/lymph for transport. Blood: Plasma + elements (RBC gas, WBC immunity, platelets clotting). Groups: ABO/Rh. Closed system, 4-chambered heart, double circulation. Cycle: Systole/diastole, 5L output. ECG records activity. Regulated myogenically/neural/hormonal. Disorders: Hypertension, CAD, etc.
Why This Guide Stands Out
Complete coverage: All subtopics, diagrams explained, Q&A (NCERT + extras), quiz. Exam-ready for 2025. Free & ad-free.
Key Themes & Tips
- Transport Efficiency: Blood/lymph roles.
- Heart Function: Cycle, regulation.
- Tip: Draw heart diagram; memorize percentages (RBC/WBC).
Exam Case Studies
Questions on clotting cascade, ECG waves, blood groups compatibility.
Project & Group Ideas
- Model heart pump; discuss lifestyle for heart health.
60+ Questions & Answers - NCERT Based (Class 11)
Structured as Part A (1 mark, short answers ~1 line), Part B (4 marks, ~6 lines/medium), Part C (8 marks, detailed/long ~15-20 lines). 20 per part, covering all subtopics with NCERT-aligned answers.
Part A: 1 Mark Questions (Short Answers)
1. Plasma percentage in blood?
1 Mark Answer: 55%.
2. Major plasma proteins?
1 Mark Answer: Fibrinogen, globulins, albumins.
3. RBC count in adult man?
1 Mark Answer: 5-5.5 million/mm³.
4. Hemoglobin in 100ml blood?
1 Mark Answer: 12-16g.
5. RBC lifespan?
1 Mark Answer: 120 days.
6. WBC count average?
1 Mark Answer: 6000-8000/mm³.
7. Most abundant WBC?
1 Mark Answer: Neutrophils (60-65%).
8. Least WBC type?
1 Mark Answer: Basophils (0.5-1%).
9. Platelet count?
1 Mark Answer: 1.5-3.5 lakh/mm³.
10. Universal donor group?
1 Mark Answer: O.
11. Universal recipient?
1 Mark Answer: AB.
12. Rh+ percentage?
1 Mark Answer: Nearly 80%.
13. Clotting enzyme from prothrombin?
1 Mark Answer: Thrombin.
14. Lymph color?
1 Mark Answer: Colorless.
15. Fish heart chambers?
1 Mark Answer: 2.
16. Mammal heart chambers?
1 Mark Answer: 4.
17. Pacemaker of heart?
1 Mark Answer: SAN.
18. Cardiac cycle duration?
1 Mark Answer: 0.8 seconds.
19. Stroke volume?
1 Mark Answer: 70ml.
20. Normal BP?
1 Mark Answer: 120/80 mmHg.
Part B: 4 Marks Questions (Medium Answers ~6 Lines)
1. Functions of plasma proteins.
4 Marks Answer: Fibrinogen: Clotting/coagulation. Globulins: Defense/immunity (antibodies). Albumins: Osmotic balance (prevent water loss from vessels). Maintain viscosity, pH. Example: Albumins keep blood volume stable.
2. Role of RBCs in gas transport.
4 Marks Answer: Contain hemoglobin (Fe-protein), binds O2 (oxyhemoglobin) in lungs, releases in tissues. Also carries CO2 (carbaminohemoglobin). Biconcave shape ↑ surface area. 98% O2 transport via Hb.
3. Types of WBCs and functions.
4 Marks Answer: Granulocytes: Neutrophils (phagocytosis), eosinophils (allergies), basophils (inflammation). Agranulocytes: Lymphocytes (B/T immunity), monocytes (phagocytosis). Percentages: Neutrophils 60%, lymphocytes 25%.
4. ABO grouping table.
4 Marks Answer: A: Antigen A, anti-B, donors A/O. B: B, anti-A, B/O. AB: A+B, none, AB/A/B/O. O: None, anti-A+B, O. Prevents agglutination in transfusions.
5. Rh incompatibility in pregnancy.
4 Marks Answer: Rh- mother + Rh+ fetus: First pregnancy safe (placenta separates), delivery exposes maternal blood → antibodies. Subsequent: Antibodies cross placenta, destroy fetal RBCs → anemia/jaundice/erythroblastosis. Prevent: Anti-Rh post-delivery.
6. Steps in blood coagulation.
4 Marks Answer: Injury → platelet/tissue factors → thrombokinase → prothrombin (Ca2+) → thrombin → fibrinogen → fibrin. Fibrin traps cells forming clot. Cascade of 12 factors.
7. Composition of lymph.
4 Marks Answer: Tissue fluid drained by lymphatics: Water, minerals (like plasma), proteins low, lymphocytes (immunity), nutrients/hormones/fats (intestinal absorption). Returns to veins near heart.
8. Open vs closed circulation.
4 Marks Answer: Open: Heart pumps to sinuses (arthropods, less regulation). Closed: Vessels (vertebrates, precise control). Closed advantageous for pressure maintenance.
9. Structure of human heart.
4 Marks Answer: 4 chambers: Right/left atria (upper, thin), ventricles (lower, thick). Septa separate. Valves: Tricuspid/bicuspid (AV), semilunar. Pericardium protects. Tilted left in thorax.
10. Nodal tissue components.
4 Marks Answer: SAN (right atrium upper, pacemaker 70-75/min), AVN (right atrium lower), AV bundle (His through septum), Purkinje fibers (ventricular walls). Autoexcitable.
11. Phases of cardiac cycle.
4 Marks Answer: Joint diastole (all relax, fill), atrial systole (contract, 30% fill), ventricular systole (contract, eject via semilunar), ventricular diastole (relax, AV open). 0.8s total.
12. Heart sounds cause.
4 Marks Answer: Lub: AV valves close (start systole). Dub: Semilunar close (end systole). Diagnostic for valve issues.
13. ECG waves meaning.
4 Marks Answer: P: Atrial depolarization. QRS: Ventricular depolarization (systole). T: Ventricular repolarization. Counts HR via QRS.
14. Pulmonary circulation path.
4 Marks Answer: RV → pulmonary artery → lungs (O2) → pulmonary veins → LA. Deoxygenated to oxygenated.
15. Systemic circulation path.
4 Marks Answer: LV → aorta → arteries → tissues (nutrients/O2) → veins → vena cava → RA. Oxygenated to deoxygenated.
16. Blood vessel layers.
4 Marks Answer: Tunica intima (endothelium), media (muscle/elastic), externa (fibrous). Veins thinner media.
17. Neural regulation of heart.
4 Marks Answer: Sympathetic (ANS): ↑ HR/force. Parasympathetic: ↓ HR/conduction. Medulla center controls.
18. Hormonal regulation.
4 Marks Answer: Adrenaline (adrenal medulla): ↑ cardiac output during stress.
19. Hypertension definition.
4 Marks Answer: >140/90 mmHg (systolic/diastolic). Leads to heart/organ damage.
20. CAD cause.
4 Marks Answer: Atherosclerosis: Deposits narrow coronary arteries, reduce blood to heart.
Part C: 8 Marks Questions (Detailed Answers ~15-20 Lines)
1. Describe blood composition and functions.
8 Marks Answer: Blood: Connective tissue for transport. Plasma (55%): Water (90%), proteins (7%: fibrinogen clotting, globulins defense, albumins osmosis), minerals (Na+, Ca2+), metabolites (glucose, lipids). Formed elements (45%): RBCs (5M/mm³, Hb 15g/dl, O2/CO2 transport, biconcave, 120 days). WBCs (7K/mm³: neutrophils 60% phagocytosis, eosinophils 2% allergies, basophils 1% histamine, lymphocytes 25% immunity B/T, monocytes 8% macrophages). Platelets (2.5L/mm³, clotting). Functions: Nutrient/O2 delivery, waste removal, immunity, clotting, pH/temperature regulation. Evolutionary: Closed system efficient. Disorders if imbalanced (anemia low RBC). Real-life: Blood donation saves lives via matching.
2. Explain ABO and Rh blood groups with compatibility.
8 Marks Answer: ABO: Antigens A/B on RBCs, antibodies in plasma. A: A antigen, anti-B (donors A/O). B: B, anti-A (B/O). AB: A+B, no antibodies (universal recipient AB/A/B/O). O: No antigens, anti-A/B (universal donor O). Mismatch: Agglutination/destruction. Rh: Antigen like rhesus monkey. Rh+ (80%, antigen), Rh- (no, forms antibodies on exposure). Transfusion: Match Rh to avoid hemolysis. Pregnancy: Rh- mother/Rh+ fetus – first safe, subsequent antibodies cross placenta → fetal RBC destruction → erythroblastosis (anemia, jaundice, brain damage). Prevention: Anti-Rh injection post-first birth neutralizes fetal Rh. Table: Donors ensure no reaction. Importance: Safe transfusions, maternal-fetal health.
3. Detail blood coagulation mechanism.
8 Marks Answer: Coagulation: Response to injury, forms fibrin clot. Steps: Trauma → platelets release factors + tissue thromboplastin → thrombokinase (Ca2+) → prothrombin → thrombin → fibrinogen → fibrin monomers → polymer mesh traps RBCs/platelets (coagulum). Intrinsic/extrinsic pathways converge. 12 factors (inactive in plasma). Role: Prevents hemorrhage, scab formation. Disorders: Hemophilia (factor VIII deficiency), thrombosis (excess). Evolutionary: Vital for survival. Example: Cut finger – dark scum in minutes. Calcium essential throughout. Serum post-clotting lacks fibrinogen.
4. Differentiate lymph and blood; role of lymph.
8 Marks Answer: Blood: Red (Hb), plasma proteins high, formed elements (RBC/WBC/platelets), vessels. Lymph: Colorless (no Hb), protein low, lymphocytes only, lymphatics. Origin: Lymph from tissue fluid (capillary leak: water/solutes out). Role: Returns fluid to blood (prevents edema), immunity (lymphocytes), absorbs fats (lacteals in villi → chyle). Exchanges via tissue fluid. System: Vessels to veins. Importance: Complements blood, drainage. Example: Intestinal fats enter lymph, not portal vein directly.
5. Describe human heart structure and conduction system.
8 Marks Answer: Heart: Muscular, 4 chambers (atria receive, ventricles pump), pericardium sac with fluid. Septa: Thin inter-atrial, thick inter-ventricular. Valves: Tricuspid (3 cusps right AV), mitral (2 left AV), semilunar (pulmonary/aorta). Conduction: Myogenic. SAN (SA node, right atrium, pacemaker 70-75 impulses/min initiates). AVN (AV node, near septum). AV bundle (His) → bundle branches → Purkinje (ventricular walls, rapid spread). Autoexcitable, action potentials cause contraction. Prevents backflow, separates circulations. Tilted left, fist-sized.
6. Explain cardiac cycle with sounds and output.
8 Marks Answer: Cycle: 0.8s (72/min). 1. Joint diastole: All relax, AV open (tricuspid/bicuspid), semilunar closed; blood fills atria → ventricles (70% passive). 2. Atrial systole: SAN impulse, atria contract (30% fill). 3. Ventricular systole: AVN → His → Purkinje; ventricles contract, AV close (lub sound), pressure ↑ → semilunar open, blood to aorta/pulmonary. 4. Ventricular diastole: Relax, semilunar close (dub), AV open. Output: Stroke volume 70ml/beat × 72 = 5L/min cardiac output. Varies (exercise ↑). Sounds: Diagnostic (murmurs = leaks).
7. Describe ECG and its significance.
8 Marks Answer: ECG: Graphical cardiac electrical activity via leads (wrist/ankle/chest). Waves: P (atrial depol./contraction), QRS complex (ventricular depol., systole start), T (ventricular repol., diastole). PR: Atrio-ventricular delay. QT: Ventricular activity. HR: Count QRS/min. Standard: 3 leads. Significance: Detects arrhythmias, ischemia, hypertrophy. Deviations: Abnormal (e.g., peaked T = hyperkalemia). Clinical: Monitors patients, pre-surgery. Example: Hospital beeps sync with QRS.
8. Explain double circulation with diagrams.
8 Marks Answer: Double: Separate pulmonary/systemic. Vessels: 3 layers (intima, media, externa). Pulmonary: Deoxygenated RA → tricuspid → RV → pulmonary artery → lungs (gas exchange) → pulmonary veins → LA. Systemic: Oxygenated LA → mitral → LV → aorta → arteries/arterioles/capillaries → tissues (O2/nutrients, CO2 waste) → venules/veins → vena cava → RA. Hepatic portal: Gut → liver (process) → hepatic veins. Coronary: Heart supply. Advantages: No mixing, efficient O2 delivery. Evolutionary: 4-chambered enables.
9. Regulation of cardiac activity mechanisms.
8 Marks Answer: Intrinsic: Myogenic (nodal autoexcitable). Neural: Medulla center via ANS. Sympathetic (accelerans): ↑ HR/force/conduction/output. Parasympathetic (vagus): ↓ HR/speed. Hormonal: Adrenaline/noradrenaline (sympathetic-like, stress ↑ output). Intrinsic: Frank-Starling (stretch ↑ force). Example: Exercise → sympathetic ↑ CO from 5 to 20L/min. Disorders: Arrhythmia if imbalanced.
10. Discuss circulatory disorders.
8 Marks Answer: Hypertension: >140/90, systolic (pump) >120, diastolic (rest) >80. Causes: Stress, diet; risks: Heart failure, stroke, kidney damage. CAD: Atherosclerosis – plaques (cholesterol/Ca/fat) narrow coronaries → ischemia. Angina: Chest pain from O2 lack (stable/unstable). Heart failure: Weak pump → congestion/edema (lungs/limbs). Not attack (damage) or arrest (stop). Prevention: Lifestyle (exercise, low salt/fat). Stats: Leading death cause globally.
11. Evolutionary changes in heart among vertebrates.
8 Marks Answer: Fish: 2-chamber (1 atrium/ventricle), single circulation (gill-body-heart). Amphibians/reptiles: 3-chamber (2 atria/1 ventricle), incomplete double (mixing in ventricle). Crocs/birds/mammals: 4-chamber (2/2), complete double (separate paths, efficient O2). Evolution: Sinus venosus → right atrium, conus arteriosus → left ventricle. Advantages: Higher metabolism in endotherms needs separation.
12. Compare open/closed systems; vertebrate hearts.
8 Marks Answer: Open: Arthropods/molluscs – heart to sinuses, low pressure. Closed: Annelids/chordates – vessels, high pressure/regulation. Vertebrates: Fish 2C single, amphibians/reptiles 3C incomplete double, crocs/birds/mammals 4C complete double. Double prevents mixing, suits terrestrial/high O2 needs.
13. Role of platelets and WBCs in defense.
8 Marks Answer: Platelets: Clotting at injury (release serotonin/ADP, aggregate). WBCs: Innate (neutrophils/monocytes phagocytose pathogens), adaptive (lymphocytes: B antibodies, T cytotoxic/helper). Eosinophils parasites/allergies, basophils histamine. Counts rise in infection (leucocytosis).
14. Significance of double circulation.
8 Marks Answer: Separates O2-rich/poor blood, efficient for warm-blooded. Pulmonary: Low pressure lungs. Systemic: High pressure body. Hepatic portal: Nutrient processing. Coronary: Heart self-supply. No mixing unlike amphibians.
15. Cardiac output calculation and factors.
8 Marks Answer: CO = SV (70ml) × HR (72) = 5.25L/min. Factors: Intrinsic (nodal rate), neural (sympathetic ↑), hormonal (adrenaline), Starling law (venous return ↑ preload → ↑ SV). Athlete: Higher due to training.
16. ECG clinical importance.
8 Marks Answer: Monitors rhythm, detects blocks (prolonged PR), infarction (ST elevation), hypertrophy (high voltage). Leads: Limb/precordial. Normal: Regular P-QRS-T. Abnormal: AFib (irregular), MI (Q waves). Non-invasive, essential cardiology.
17. Lymphatic system structure/function.
8 Marks Answer: Vessels (capillaries collect tissue fluid → larger ducts → veins at subclavian). Nodes filter pathogens. Spleen/tonsils. Functions: Fluid balance, immunity (lymphocytes mature), fat absorption. Blockage: Lymphedema.
18. Heart failure vs angina vs CAD.
8 Marks Answer: CAD: Plaque buildup. Angina: Symptom (pain from ischemia). Failure: Chronic weak pump → fatigue/edema. CAD causes both; failure from prolonged damage.
19. Evolutionary heart progression.
8 Marks Answer: From 2C (fish, venous blood) to 4C (mammals, separated). 3C reptiles: Partial septum reduces mixing. Crocs: Full 4C. Adaptation for O2 demand.
20. Prevention of erythroblastosis foetalis.
8 Marks Answer: Rh- mother screened. If Rh+, inject anti-Rh (RhoGAM) at 28 weeks/delivery. Antibodies destroy fetal RBCs in mother, prevent sensitization. Subsequent pregnancies safe.
Practice Tip: Diagrams for long answers; time yourself.
