Body Fluids and Circulation
Class 11 · Biology
5 ideas in Class 11 Biology, explained in plain words, with games and quizzes to practise.
Plasma and Formed Elements
Part of: Fluids and Groups
Straw fluid carries proteins for clotting, defence and balance; minus clotters it is serum. Red cells crowd millions per unit with haemoglobin for four-month stints; white cells split eaters, signallers and guards; fragments plug leaks while lymph ferries fats and fighters.
Why it matters. Protein jobs explain fluid tests. Cell counts diagnose health.
Key words
- Plasma
- : Straw fluid carrying proteins, salts and dissolved goods.
- Serum
- : Fluid left when clotting proteins are used up.
- Fibrinogen
- : Clotting protein turned into fibrin threads at leaks.
- Erythrocytes
- : Red disc cells packed with oxygen-carrying pigment.
- Leucocytes
- : White defender cells that eat germs or signal alarms.
- Platelets
- : Cell bits that plug leaks by starting clots.
- Haemoglobin
- : Oxygen-carrying red pigment inside red cells.
Try it in two minutes
- Name three plasma proteins.
- Rank white cell shares.
- Match each cell with its job.
Try at home. Read a fluid test report.
Groups and Clotting
Part of: Fluids and Groups
Red-cell antigens A and B with plasma antibodies sort four groups; O suits all while AB accepts all. Rh mismatch threatens later positive babies of negative mothers unless anti-Rh mops up. Fibrin nets trap cells via thrombin cascades needing kinase and calcium.
Why it matters. Antigen tables guide safe transfers. Cascade logic explains clot timing.
Key words
- ABO groups
- : A, B, AB and O sorting by red-cell surface markers.
- Antigen
- : Surface marker on red cells that decides the group.
- Antibody
- : Plasma protein that clumps foreign red cells.
- Universal donor
- : Group O red cells, accepted by every group.
- Universal recipient
- : Group AB plasma, tolerating every donor group.
- Rh factor
- : Surface marker whose mismatch harms later pregnancies.
- Fibrin
- : Mesh protein that traps cells to seal a leak.
Try it in two minutes
- Fill the four-group table.
- Trace Rh sensitisation.
- Order fibrinogen to fibrin.
Try at home. Chart safe donor-recipient pairs.
Heart and Cardiac Cycle
Part of: Heart and Circulation
Pericardial four-chamber pumps gate flaps and semilunar exits; SAN paces seventy-odd impulses through AVN, bundles and fibres. Joint rest fills, atrial squeeze tops up thirty percent, ventricular squeeze shuts flaps and opens exits with lub then dub; seventy millilitres times seventy-two beats totals five litres while P, QRS and T trace the electrics.
Why it matters. Node order explains ECG waves. Volume-rate math yields output.
Formulas
- Cardiac output = stroke volume x heart rate
- Output = 70 mL x 72 beats = about 5000 mL
Key words
- Pericardium
- : Sac with fluid that bags and guards the heart.
- SAN
- : Natural pacemaker firing the most impulses per minute.
- AVN
- : Relay passing the impulse from atria to ventricles.
- Atrial systole
- : Atrial squeeze topping ventricular filling by thirty percent.
- Lub and dub
- : Valve-snap sounds marking closure of heart flaps.
- ECG
- : P, QRS and T tracing of the hearts electrics.
Try it in two minutes
- Order SAN to fibres.
- Stage one full cycle.
- Multiply stroke by rate.
Try at home. Feel pulse for fifteen seconds.
Circulation Pathways
Part of: Heart and Circulation
Arthropods pool fluid in sinuses while chordates pipe closed loops; fish run two chambers single, amphibians three chambers mixed, crocodiles-birds-mammals four chambers split. Lung loops exchange while body loops deliver; gut-liver portals and heart-only coronaries specialise; vessel walls layer thin in veins.
Why it matters. Chamber counts predict mixing. Loop maps explain delivery routes.
Formulas
- Normal resting pressure = 120/80 mmHg
- High pressure = 140/90 mmHg or above
Key words
- Open circulation
- : Fluid pooling in open sinuses, as in arthropods.
- Closed circulation
- : Fluid piped in closed vessel loops, as in chordates.
- Pulmonary circulation
- : Lung loop that loads oxygen and drops carbon dioxide.
- Systemic circulation
- : Body loop that delivers oxygen to tissues.
- Hepatic portal system
- : Gut-to-liver routing that processes nutrients first.
- Double circulation
- : Two fully separate heart loops in birds and mammals.
Try it in two minutes
- Sort hearts by chambers.
- Trace lung versus body loops.
- Read 120 over 80.
Try at home. Chart double circulation flow.
Regulation and Disorders
Part of: Control and Disorders
Self-exciting muscle answers medulla nerves speeding or slowing beats while adrenal hormones lift output. Plaque narrows coronaries into ache, weak pumps congest lungs, stops silence beats and attacks scar muscle; numbers and symptoms separate the four.
Why it matters. Nerve-hormone balance tunes output. Symptom logic separates emergencies.
Key words
- Myogenic heart
- : Heart muscle that excites itself without nerve orders.
- Sympathetic signals
- : Nerve signals that speed up the heartbeat.
- Parasympathetic signals
- : Nerve signals that slow down the heartbeat.
- Atherosclerosis
- : Fat-cholesterol deposits narrowing coronary vessels.
- Angina pectoris
- : Pain of a heart muscle starved of oxygen.
- Heart failure
- : Pump too weak to push enough fluid to the body.
- Heart attack
- : Death of heart muscle when its supply is blocked.
Try it in two minutes
- Split sympathetic from parasympathetic.
- Name three vessel deposits.
- Separate failure, arrest, attack.
Try at home. Check pulse before and after stairs.
What your child will practise
- Circulation Pathways: Space Quick Fire (Quick Fire)
- Groups and Clotting: Ocean Puzzle (Clue Puzzle)
- Heart and Cardiac Cycle: Jungle Quick Fire (Quick Fire)
- Plasma and Formed Elements: Candy Quest (Flip and Match)
- Regulation and Disorders: Desert Puzzle (Clue Puzzle)
- Quiz: Circulation Pathways (8 questions)
- Quiz: Groups and Clotting (8 questions)
- Quiz: Heart and Cardiac Cycle (8 questions)
- Quiz: Plasma and Formed Elements (8 questions)