Body Fluids and Circulation

Living cells need nutrients and oxygen and must remove wastes, so a fluid must circulate. Blood is a special connective tissue made of plasma (about 55%) and formed elements (about 45%). Plasma is 90-92% water with proteins such as fibrinogen, globulins and albumins. The formed elements are erythrocytes (about 5 to 5.5 million per cubic mm, living about 120 days), leucocytes (6,000 to 8,000 per cubic mm) and platelets (1.5 to 3.5 lakh per cubic mm). You will study the ABO and Rh blood groups, erythroblastosis foetalis, blood coagulation through thrombin and fibrin, and lymph. You will then study open and closed circulatory systems and the human heart with its four chambers, valves and nodal tissue: the SA node (pacemaker), AV node, bundle of His and Purkinje fibres. The chapter explains the cardiac cycle of about 0.8 seconds, stroke volume and cardiac output, heart sounds and the ECG with its P wave, QRS complex and T wave. It also covers double circulation, its regulation, and disorders like hypertension, coronary artery disease, angina and heart failure.

Detailed Worksheet: Body Fluids and Circulation Section A - Definitions (10 marks) 1. What is the composition of blood plasma? (2 marks) 2. What is erythroblastosis foetalis? (2 marks) 3. What is the role of the SA node? Why is it called the pacemaker? (2 marks) 4. Define stroke volume and cardiac output. (2 marks) 5. What is lymph? How does it differ from blood? (2 marks) Section B - Calculations and Applications (15 marks) 6. A person's heart beats 72 times per minute with a stroke volume of 70 mL. Calculate the cardiac output in mL per minute and litres per minute. What will happen to the cardiac output if the heart rate rises to 120 per minute during exercise with the same stroke volume? (3 marks) 7. The cardiac cycle lasts 0.8 seconds. Calculate the heart rate per minute. If atrial systole lasts 0.1 s and ventricular systole 0.3 s, calculate the duration of joint diastole when all chambers relax, given that ventricular systole begins just as atrial systole ends. (3 marks) 8. A blood test shows 5 million RBCs per cubic mm. An adult has about 5 litres of blood. Calculate the total number of RBCs (1 litre = 10^6 cubic mm). If RBCs live 120 days, how many are destroyed each day on average? (3 marks) 9. A WBC count of 8,000 per cubic mm shows neutrophils 62%, lymphocytes 25%, monocytes 7%, eosinophils 5% and basophils 1%. Calculate the number of each type per cubic mm. Which are the most abundant and the least abundant? (3 marks) 10. A person's blood pressure reading is 150/95 mm Hg. Interpret it compared to the normal value of 120/80 mm Hg. Name the condition and two organs it can damage. (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the section of the human heart showing chambers, valves and major blood vessels. (4 marks) 12. Draw a standard ECG and label the P wave, QRS complex and T wave. (3 marks) 13. Draw a flowchart showing the steps of blood coagulation. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Explain the ABO blood grouping system. Why is O called the universal donor and AB the universal recipient? Explain what happens if incompatible blood is transfused. (5 marks) 15. Explain the events of the cardiac cycle and the origin of the heart sounds. How is the heartbeat initiated and conducted? (5 marks) 16. Explain double circulation in humans. Compare the circulation in fishes, amphibians and mammals, and explain the importance of complete separation of oxygenated and deoxygenated blood. (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw diagrams neatly with labels. Show the steps of calculations with units.