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Miracle Learning Centre Science Tuition Question on Circulatory System. (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition) 1 Fig. 1.1 shows the changes in blood pressure (A), velocity (B) and cross sectional area (C) of the blood vessels of the systemic circulation as blood flows and returns to the heart.

(a) State the relationship between the velocity of the blood and the total cross sectional area of the blood vessels. (b) (i) Comment on the rate of blood flow through the capillaries. (ii) Explain the importance of this in relation to the function of the capillaries. (c) Explain how the velocity of blood (i) is maintained in the arteries, despite fluctuations in blood pressure, (ii) in the veins increases, while the blood pressure continues to fall. 2(a) Fig. 5.1 shows how a blocked blood vessel in the heart can be by-passed using an artificial blood vessel. Fig 5.1

(i) Name the blocked blood vessel. (ii) Identify structures P and Q on Fig. 5.1. P -------------------------------------- Q ---------------------------------------- b) Sometimes, instead of an artificial blood vessel being used for the graft, a vein is taken from elsewhere in the patient’s body. Suggest two ways in which a vein might not be as suitable for carrying blood to the heart muscle as the blood vessel in the heart before it became blocked.

c) Fig. 5.2 shows the same blood vessel, as in (a)(i) but this time the blockage is being treated with the use of a ‘stent’.

(i) Name two components of the material that is causing the blockage at R.

(ii) Suggest and explain why patients are given ‘anti-platelet’ drugs before inserting the stent. Miracle Learning Centre Answer to Science Tuition Question on Circulatory System. (O Level Science Tuition/IP Science Tuition/Secondary Science Tuition)

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