ICSE Class 10th Biology Study Guide

1. “The Circulatory System”CBSE Class 10

2. Blood • A finely regulated circulatory system in the human body ensures the transportation of important substances and also the maintenance of homeostasis. The components of circulatory system are blood, lymph, heart and vessels. The blood vascular system may be of two types: Open Circulatory System and Closed Circulatory System. • In open type of circulation, blood vessels open into large space called sinuses.The body fluid is called hemolymph that flows from the heart to the peripheral organs and the body cavity. • In closed type of circulatory system, blood is closed within the vessels. These vessels are of different size and hav...  • Blood is a fluid connective tissue comprising of a fluid matrix called plasma and formed elements. In the plasma, RBCs, WBCs and platelets are suspended.RBCs are non-nucleated cells and red in colour due to the presence of the pigment called haemoglobin.WBCs protect the body against infectious diseases and foreign particles.Platelets are small, oval, rounded or biconvex disc like bodies with colourless and granular cytoplasm without nucleus.

3. Blood Vessels • Blood vessels are the most important components of the circulatory system.In humans, blood always flows in closed vessels and tubes throughout the body. This is called closed circulatory system. The blood vessels that carry blood are of three types: arteries, veins and capillaries. • Arteries carry oxygenated blood from heart to body parts. They have thick elastic walls. Arteries are divided into arterioles which are further divided into smallest vessels called capillaries where actual diffusion takes place. Veins carry deoxygenated blood towards the heart. They have walls present to prevent backflow of blood.  • Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. Systemic veins return deoxygenated blood from rest of the body to the right atrium of the heart. Superficial veins are located close to the surface of the skin. Deep veins are located deep within muscle tissue.  Vein can range in size from 1 millimeter to 1-1.5 centimeters in diameter. Venules are the smallest veins in the body. Vena cava is the largest vein in the body.In blood transfusion, blood is drawn from vein instead of artery.Capillaries are small blood vessels which are located within the tissues. They are composed of endothelial cells.They help in the exchange of oxygen, carbon dioxide, nutrients and wastes.

4. Structure of Heart • Heartis the pumping organ of our circulatory system. Heart is divided into four chambers: two upper chambers are called the left and right auricles and two lower chambers are called left and right ventricles. • A muscular septum divides the heart into left and right heart. In right half, deoxygenated blood flows and simultaneously oxygenated blood flows in the left half. • The external structure of the heart comprises of pericardium, atrio-ventricular groove and inter-ventricular groove.External heart lies in thoracic cavity and is protected by rib cage. • Internal Structure comprises chambers of heart and Valves of Heart. The wall of heart is divided into three layers: epicardium (outer layer), myocardium (middle layer), endocardium (inner layer). • The valves of significance are bicuspid valve, tricuspid valve and two semi lunar valves. The great blood vessels of the heart include vessels that enter or leave the heart. Superior Vena Cava carries deoxygenated blood from head and upper half of body to heart's right atrium whereas inferior vena cava carries deoxygenated blood from lower half of body to the right atrium of heart. Blood vessels leaving the heart comprise of pulmonary trunk and systemic aorta. Pulmonary trunk is further comprised of pulmonary vein and pulmonary aorta.

5. Blood Flow Through Heart • Heart is divided into four chambers: two upper chambers are called the left and right auricles and two lower chambers are called left and right ventricles. A muscular septum divides the heart into left and right heart. In right half, deoxygenated blood flows and simultaneously oxygenated blood flows in the left half. Arteries carry oxygenated blood while veins carry deoxygenated blood. • Blood flow in heart in one direction only. Sets of valves close to prevent the backflow of blood. The atrio- ventricular or AV valves prevent blood from returning to atria when ventricles contract. The semilunar valves guard the opening to the pulmonary. • Pulmonary circulation involves the movement of blood from heart to lungs and back to heart again. Systemic circulation carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. Thus, blood flows through the heart twice. • Portal circulation occurs when a capillary bed drains into another capillary bed through veins, without first going through the heart. Hepatic portal system carries blood from the GI tract and spleen to the liver before it enters the inferior vena cava and the general circulation.

6. Lymphatic System • Lymphatic system is the interconnected system of spaces and vessels between body tissues and organs through which lymph circulates.It works in union with circulatory system and comprises of lymph, lymph vessels and lymphatic organs. • Lymph is a clear watery fluid that resembles the blood plasma. It is derived from blood and returns to blood. Lymph carrying vessels are very similar to the veins and capillaries. • Lymph vessels are thin walled and lined by endothelial cells. As blood flows from the arterial end to its venous end, its fluid plasma filters out of the thin walled capillaries at the arterial end. • Lymphatic system plays a vital function in waste elimination, fluid distribution, immune response, metabolic regulation and nutrient distribution. • Lymphatic organs are spleen, lymph node and thymus. Lymph nodes are small bean shaped structures and their main function is lymph filtration. Tonsils are located in posterior wall of nasopharynx. • These are multiple aggregations of large number of lymphatic nodules embedded in mucous membrane.

7. Extramarks’ Approach • ICSE Biology Class 10th Solutions are available on Extramarks. Extramarks provides a student with reading and study material that will benefit a student to score better in a subject like Biology. Biology as a subject requires a lot of retention and learning. By using Extramarks, a student will get to know about the basic concepts of the subject. Concept Clarity is the basic tip that is used by Extramarks.https://www.extramarks.com/study-material/icse-class-10/biology

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