Biology Class 11 NCERT Solutions: Chapter 18 Body Fluids and Circulation Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 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 vs Lymph
1.Blood is a red-coloured fluid that contains RBCs.1.Lymph is a colourless fluid that lacks


2.It contains plasma, , , 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 system of circulation

Systems of Circulation
Open system of circulationClosed 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.5.This system is present in annelids,

echinoderms, and vertebrates.

The Open Circulatory System
The Closed Circulatory System

(C) Systole and diastole

Systole vs 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


Image Shows the Systole
Image Shows the Diastole

(D) P-wave and T-wave

P-Wave vs T-Wave
1.In an electrocardiogram (ECG) , the P wave indicates the activation of the SA


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.
Image Shows the Waveforms

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