NCERT Book Class 11 Biology Chapter 15 Body Fluids and Circulation

BODY FLUIDS AND CIRCULATION 193

CHAPTER 15
BODY FLUIDS AND CIRCULATION
15.1 Blood You have learnt that all living cells have to be provided with nutrients, O2
and other essential substances. Also, the waste or harmful substances
15.2 Lymph (Tissue
produced, have to be removed continuously for healthy functioning of
Fluid)
tissues. It is therefore, essential to have efficient mechanisms for the
15.3 Circulatory movement of these substances to the cells and from the cells. Different
Pathways groups of animals have evolved different methods for this transport. Simple
15.4 Double organisms like sponges and coelenterates circulate water from their
Circulation surroundings through their body cavities to facilitate the cells to exchange
these substances. More complex organisms use special fluids within their
15.5 Regulation of bodies to transport such materials. Blood is the most commonly used body
Cardiac fluid by most of the higher organisms, including humans, for this
Activity purpose. Another body fluid, lymph, also helps in the transport of
15.6 Disorders of certain substances. In this chapter, you will learn about the composition
Circulatory and properties of blood and lymph (tissue fluid) and the mechanism of
System circulation of blood is also explained herein.

15.1 BLOOD

Blood is a special connective tissue consisting of a fluid matrix, plasma,
and formed elements.

15.1.1 Plasma
Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of
the blood. 90-92 per cent of plasma is water and proteins contribute 6-8
per cent of it. Fibrinogen, globulins and albumins are the major proteins.