1. The figure below shows sections through two types of human blood vessel.
(a) Name the types of blood vessel shown in the figure above.
(b) (i) Describe two differences in the structure of blood vessels A and B.
(ii) For each of your answers in (b)(i), explain how the difference in structure relates to the function of the blood vessel.
(c) Blood vessels can sometimes be damaged when a person cuts himself. Outline the main stages in blood clotting
2. (a) Describe coronary heart disease.
It has been suggested that eating a balanced diet may help to prevent heart disease.
Besides a balanced diet, state one other factor that may decrease the risk of heart diseases.
(b) ln the human body, blood carries out both protective and transport functions. Describe the role of white blood cells in protecting the body, the role of red blood cells and plasma in transport of substances.
3. Fig. 2.1 shows the results of five independent investigations into the effect of physical activity on heart disease.
(a) With reference to data from Fig. 2, describe the effect of level of physical activity on the risk of heart disease.
Use information about the circulatory system to account for the trend observed.
(d) Fig. 2.2 shows how the blood pressure changes in artery, capillaries and veins.
Describe how the pressure changes from arteries, capillaries to the vein. Explain how the structures of arteries and vein are adapted to the pressure and allow blood to flow continuously.
1. (a) A: Artery; B: Vein
(b) (i) A/artery is thicker walled than vein;
A/artery has smaller lumen than vein;
B/vein has valve, artery does not
(ii) artery has to withstand greater (blood) pressure; (reject if students use ‘generate’)
blood moves at a faster speed in artery than in vein;
valve needed to prevent backflow in vein as blood is at low pressure in veins
(c) damaged tissue and platelets produce enzyme thrombokinase;
thrombokinase converts inactive prothrombin into thrombin:
thrombin converts soluble fibrinogen into insoluble fibrin;
red blood cells and platelets are trapped in the mesh of fibrin threads to form a blood clot.
2. (a) Besides a balanced diet, state one other factor that may decrease the risk of heart diseases.
Coronary heart disease is due to the deposition of fats and cholesterol in the lumen of the coronary arteries.
This reduces the blood supply to the heart muscles. hence decreasing supply of oxygen and glucose to the heart muscles.
Resulting in lower rate of respiration, hence lesser energy release for heart muscle contraction, resulting in heart attack. To reduce the risk of coronary heart disease, a person should exercise regularly/do not smoke/do not drink excessively/maintain healthy weight.
- Lymphocytes produce antibodies/ cause bacteria to clump
- Lymphocytes recognise and reject foreign tissue
- Phagocytes engulf and ingest foreign bacteria
- Red blood cells transport oxygen from lungs to all body cells
- Plasma transport blood cells/ions/soluble food substances; hormones/carbon dioxide/urea/vitamins/plasma proteins
3. (a) As the level of physical activity increases. the risk of dying from the heart disease decrease. As the level of physical activity increases, there is increased blood flow, hence increasing supply of oxygen and glucose to the heart muscles.
This allows sufficient oxygen and glucose available for cellular respiration, hence releasing sufficient energy for heart muscle contraction.
Exercise also helps keep the arteries elastic, allowing fats and cholesterol to be able to move easily in the blood.
Exercise also improves blood circulation so that it reduces the chances of blood clots leading to heart attack.
- The pressure is highest at arteries and the pressure decreases, the pressure is the lowest at the veins
- The pressure changes at artery due to contraction and relaxation of the heart
- The wall of artery is thicker to withstand the higher blood pressure
- The pressure of vein is low and the wall is thinner
- Valves are present in veins to prevent backflow of blood