ICSE Class 10 Biology Chapter 07 The Circulatory System

Are you looking for the ICSE Class 10 Biology book PDF free download. You have come to the right place as we have provided the PDF for Chapter 7 The Circulatory System here. You can refer to the link below to download the ICSE Class 10 Biology Book in PDF Chapter 7 The Circulatory System which is highly recommended textbook for students following the ICSE syllabus for this year. This book has been published by Selina Concise for this academic year and covers important concepts in a detailed manner. Students of ICSE Class 10 will be easily able to understand all concepts and will help students to build a strong foundation in the subject. One of the key chapters in this book is Chapter 7 The Circulatory System which explains all the important topics in lot of detail. The Biology book for Class 10 follows the latest ICSE syllabus for the current year thus ensuring that students get updated with the most relevant content for their studies. By downloading the Selina Concise Biology Class 10 Textbook PDF, students can conveniently access the book anytime and study without needing a physical copy.

Syllabus

Circulatory System: Main features; the structure and working of the heart, blood vessels, structure and functions of blood and circulation of blood (only names of the main blood vessels entering and leaving the heart, liver and kidney will be required).

Scope of Syllabus: Composition of blood (Structure and functions of RBC, WBC and platelets). Brief idea of tissue fluid and lymph. Increase in efficiency of mammalian red blood cells due to absence of certain organelles should be explained with reasons. A brief idea of blood coagulation. Structure of vein, artery and capillary should be explained with the help of diagrams to bring out clearly the relationship between their structure and function. ABO blood group system, Rh factor; concept of double circulation; concept systole and diastole; blood pressure. Reference to portal system should be made. Working of the heart along with names of the main blood vessels entering and leaving the heart, the liver and the kidney must be taught. Examination of a blood smear under a microscope.

Almost all organisms, including humans, have some kinds of fluids circulating in their bodies. Such fluids constitute the distributing system (to supply substances) as well as a collecting system (to pick up substances) to and from the various parts of the body including the remotest cell. In this chapter, we will study about the circulating fluids in our body, its composition and function.

7 A. Body Fluids

7.1 Need For Transport Inside The Body

Every organ in our body requires the involvement of the circulating body fluids. For example:

The digestive system digests and absorbs nutrients which are needed to be transported to every body cell.

The respiratory system draws in air, and the oxygen picked up from it in the lungs has to be transported to all parts of the body. Similarly, the CO₂ collected from the entire body has to be carried to the lungs for giving out.

All the extra water, excess salts, and the nitrogenous wastes such as urea have to be removed from different parts and have to be sent to the excretory system to be thrown out of the body.

Hormones secreted by the endocrine system have to be carried throughout the body by the circulating blood to act wherever required, and so on.

All such functions that need transport are performed by the two circulating fluids - the blood and the lymph. Besides transport, these fluids have some other functions also.

7.2 Fluids In Our Body

There are three principal fluids in our body:

(i) Blood, contained in the heart and in the blood vessels (arteries, veins and capillaries) of the circulatory system,

(ii) Tissue fluid, occupying spaces between cells in the organs, and

(iii) Lymph, which is contained within lymph vessels and lymphatic organs such as the spleen and the tonsils.

Fig. 7.1 shows a diagrammatic representation of the relationship between blood, tissue fluid and lymph as they circulate in their respective vessels or spaces between the cells in different organs. It is clear from the diagram that blood in our body circulates in a closed manner i.e. all the time through blood vessels.

Such a type of blood circulation is called a closed vascular system. As against this, in certain animals such as insects, the blood mostly flows through open spaces, called an open blood circulatory system. Their blood flows from the heart to body tissue spaces without vessels.

Non-circulating fluids: There are also some other fluids located in particular organs such as synovial fluid filled in the cavities of skeletal joints, vitreous humour in the eye, etc. They do not circulate.

7.3 The Blood

Never Stationary. Blood is always in motion from the heart to the arteries and back through the veins.

Colour. The blood is a somewhat thick fluid, bright red when taken from an artery or dark red when taken from a vein. [Conventionally, in the diagram, we show the veins in blue - this is just for contrast; the blood inside the veins is not blue, it is actually dark red].

Volume. An average adult human contains 5 to 6 litres of blood by volume in his body.

Taste - saltish. Perhaps we have all "tasted" our blood as in the case when there is a cut in the tongue or bleeding from the gums. The blood is slightly alkaline with a pH of 7.3 to 7.45 (7 is neutral, neither acidic nor alkaline).

7.4 Functions Of Blood

The main functions of the blood in our body can be treated under two broad headings: (A) Transport and (B) Protection.

A. Transport By Blood

(Transport of digested food, oxygen, carbon dioxide, excretory substances, hormones, body heat).

1. Transport of digested food from the alimentary canal to the tissues. These substances are simple sugars like glucose, amino acids, vitamins, mineral salts, etc.

2. Transport of oxygen from the lungs to the tissues. It occurs by means of red blood cells in combination with haemoglobin in the form of an unstable compound oxyhaemoglobin, which on reaching the tissues breaks up to deliver oxygen. Hb + O₂ \rightleftharpoons Hb + O₂ (Oxyhaemoglobin)

3. Transport of carbon dioxide from the tissues to the lungs. It occurs partly in combination with haemoglobin and partly as solution in blood plasma. Hb + CO₂ \rightleftharpoons Hb.CO₂ (Carbaminohaemoglobin)

4. Transport of excretory material from the tissues to the liver, kidney or the skin for elimination or to render them harmless.

5. Distribution of hormones secreted by special glands (endocrine glands) directly into the blood.

6. Distribution of heat. The blood helps in keeping the temperature of the body uniform by distributing heat.

B. Protection By Blood

1. Blood forms a clot wherever there is a cut in a blood vessel. The clot serves to prevent (i) further loss of blood and (ii) the entry of disease-causing germs.

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