Question 7
Write the differences between:
(a) Blood and Lymph
(b) Open and Closed system of circulation
(c) Systole and Diastole
(d) P-wave and T-wave
(a) Blood and lymph
| Blood |
| Lymph |
1. | Blood is a red-coloured fluid that contains RBCs. | 1. | Lymph is a colourless fluid that lacks RBCs. |
2. | It contains plasma, RBCs, WBCs, and platelets. It also contains proteins. | 2. | It contains plasma and lesser number of WBCs and platelets. It lacks proteins. |
3. | Blood transports nutrients and oxygen from one organ to another. | 3. | Lymph plays a role in the defensive system of the body. It is a part of the immune system. |
(b) Open and closed systems of circulation
| Open system of circulation |
| Closed system of circulation |
1. | In this system, blood is pumped by the heart, through large vessels, into body cavities called sinuses. | 1. | In this system, blood is pumped by the heart, through a closed network of vessels. |
2. | The body tissues are in direct contact with blood. | 2. | The body tissues are not in direct contact with blood. |
3. | Blood flows at low pressure. Hence, it is a slower and less efficient system of circulation. | 3. | Blood flows at high pressure. Hence, it is a faster and more efficient system of circulation. |
4. | The flow of blood is not regulated through the tissues and organs. | 4. | The flow of blood can be regulated by valves. |
5. | This system is present in arthropods and molluscs except cephalopods | 5. | This system is present in annelids, echinoderms, and vertebrates. |
(c) Systole and diastole
| Systole |
| Diastole |
1. | It is the contraction of the heart chambers to drive blood into the aorta and the pulmonary artery. | 1. | It is the relaxation of the heart chambers between two contractions. During diastole, the chambers are filled with blood. |
2. | Systole decreases the volume of the heart chambers and forces the blood out of them. | 2. | Diastole brings the heart chambers back into their original sizes to receive more blood. |
(d) P-wave and T-wave
| P-wave |
| T-wave |
1. | In an electrocardiogram (ECG), the P-wave indicates the activation of the SA node. | 1. | In an electrocardiogram (ECG), the T-wave represents ventricular relaxation. |
2. | During this phase, the impulse of contraction is generated by the SA node, causing atrial depolarisation. | 2. | During this phase, the ventricles relax and return to their normal state. |
3. | It is of atrial origin. | 3. | It is of ventricular origin. |
