8.5 Summary
- Nutrients and oxygen are required by cells for cellular respiration. These are trans-
ported by blood to the various cells. - Carbon dioxide and other waste products need to be transported from the cells to the
exterior. This is also transported via blood. - Blood is pumped through the heart under high pressure to the various parts of the
body. - The left side of the heart receives deoxygenated blood from the body via veins and
sends it to the lungs to be oxygenated. - The right side of the heart receives oxygenated blood from the lungs and sends it via
arteries to all parts of the body. - The lymphatic system is composed of lymph vessels, lymph nodes, and organs.
- Lymph vessels assist the circulatory system and all the cells of the body by removing
wastes, germs and excess water from the tissue fluid. - There are many diseases that affect the heart and circulatory system and many treat-
ments are available.
Exercise 8 – 1: End of chapter exercises- The following diagrams show the heart during the cardiac cycle. The arrows represent
the flow of blood. Study the diagrams and answer the questions that follow:
a) Identify the structures labelled A and B respectively.
b) Name and explain what happens in each of the phases of the cardiac cycle rep-
resented in:
i. Diagram I
ii. Diagram II
iii. Diagram III- Loss of a lot of blood, vomiting and diarrhoea often causes a decrease in blood volume.
As a result, blood cannot move normally around the body, as blood vessels are not
completely full. The tissues do not get enough blood, leading to possible death of
cells and hence damage to organs.
a) Explain why severe vomiting and diarrhoea would cause a decrease in the blood
volume.
b) What is the relationship between blood volume and blood pressure?
248 8.5. Summary