1. The table below shows the different stages in a cardiac cycle. Name each stage and complete the table.
Answer
2. Transpiration is a passive process. What does the term passive mean ?
Answer
Does not require energy/ATP.
3. The figure below shows a basic plan of the circulatory system of a mammal. Identify the blood vessels A, B, C, D, E, F.
Answer
A = Pulmonary artery,
4. The figure below shows the changes in pressure in the left side of the heart, in the atrium, ventricle and aorta. For each of the points, A, B, C and D, identify which valves are open and which are closed.
Answer
A: Atrioventricular valve closes because ventricular pressure is now greater than the pressure in the atria. Semilunar valve remains closed because ventricular pressure is lower than pressure in the aorta.
B: Semilunar valve opens because ventricular pressure exceeds pressure in aorta.
C: Semilunar valve now closes because ventricular pressure is now lower than aorta pressure.
D: Atrioventricular valve opens because pressure in atria is greater than pressure in the ventricles.
5. Sketch a line in the figure above to represent the pressure changes in the right ventricle.
Answer
The right ventricular wall is thinner, so it does not generate as much pressure when it contracts. The right ventricle only has to pump blood to the lungs, which is why it has a thinner wall. This means the line drawn follows the same pattern as the left ventricle, but at a lower level.
6. The figure below shows how tissue fluid is formed and returned to the blood system. Tissue fluid is forced out of the capillary at A. Explain how.
Answer
High hydrostatic pressure, which is caused by pumping of the left ventricle of the heart.
7. The water potential of the blood at B is lower than the water potential of the body tissues. Explain why.
Answer
Water has been lost from the blood plasma, while large plasma proteins remain in the capillary.
8. Describe how tissue fluid is reabsorbed at B.
Answer
Water from the tissue fluid passes into the capillary by osmosis, and solutes follow by diffusion.
9. A diet that is very low in protein can result in kwashiorkor. Children with this condition have enlarged abdomens caused by accumulation of tissue fluid. Explain how.
Answer
A lack of plasma proteins means the water potential of the blood at the venule end (at B) is not low enough. As a result, water is not reabsorbed by osmosis and remains in the tissues, leading to fluid accumulation.
10. Filariasis occurs when a parasitic worm blocks the lymph vessels in the leg. This causes accumulation of tissue fluid in the leg. Explain how.
Answer
Tissue fluid cannot drain into lymph vessels (and into blood).