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Body Fluids and Circulation - Double circulation

Grade 11CBSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Double Circulation is the process where blood passes through the heart twice for each complete circuit of the body, consisting of Pulmonary and Systemic circulation.

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Pulmonary Circulation: This circuit carries deoxygenated blood from the Right VentricleRight\ Ventricle to the lungs for oxygenation and returns oxygenated blood to the Left AtriumLeft\ Atrium. Pathway: Right Ventricle→Pulmonary Artery→Lungs→Pulmonary Veins→Left AtriumRight\ Ventricle \rightarrow Pulmonary\ Artery \rightarrow Lungs \rightarrow Pulmonary\ Veins \rightarrow Left\ Atrium.

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Systemic Circulation: This circuit carries oxygenated blood from the Left VentricleLeft\ Ventricle to all body tissues via the AortaAorta and returns deoxygenated blood to the Right AtriumRight\ Atrium via the Vena CavaVena\ Cava. Pathway: Left Ventricle→Aorta→Arteries→Capillaries→Veins→Vena Cava→Right AtriumLeft\ Ventricle \rightarrow Aorta \rightarrow Arteries \rightarrow Capillaries \rightarrow Veins \rightarrow Vena\ Cava \rightarrow Right\ Atrium.

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Hepatic Portal System: A specialized vascular connection where the Hepatic Portal VeinHepatic\ Portal\ Vein carries blood from the gastrointestinal tract and spleen to the liver before it is delivered to the systemic circulation.

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Coronary Circulation: A dedicated system of blood vessels (Coronary Arteries and Cardiac Veins) responsible exclusively for the circulation of blood to and from the cardiac musculature.

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Significance: Double circulation prevents the mixing of oxygenated (O2O_2) and deoxygenated (CO2CO_2-rich) blood, ensuring a highly efficient supply of oxygen to the body, which is essential for homeothermic (warm-blooded) animals.

📐Formulae

Pulmonary Circuit:RV→Pulmonary ArteryLungs→Pulmonary VeinsLAPulmonary\ Circuit: RV \xrightarrow{Pulmonary\ Artery} Lungs \xrightarrow{Pulmonary\ Veins} LA

Systemic Circuit:LV→AortaBody Tissues→Vena CavaRASystemic\ Circuit: LV \xrightarrow{Aorta} Body\ Tissues \xrightarrow{Vena\ Cava} RA

Cardiac Output=Stroke Volume×Heart RateCardiac\ Output = Stroke\ Volume \times Heart\ Rate

💡Examples

Problem 1:

Trace the path of a molecule of CO2CO_2 from the tissues of the leg to the point where it is expelled into the alveoli of the lungs.

Solution:

Leg Tissues→Systemic Veins→Inferior Vena Cava→Right Atrium→Right Ventricle→Pulmonary Artery→AlveoliLeg\ Tissues \rightarrow Systemic\ Veins \rightarrow Inferior\ Vena\ Cava \rightarrow Right\ Atrium \rightarrow Right\ Ventricle \rightarrow Pulmonary\ Artery \rightarrow Alveoli.

Explanation:

The CO2CO_2 produced in the leg tissues enters the systemic venous system, travels to the right side of the heart, and is pumped via the pulmonary artery to the lungs for gas exchange.

Problem 2:

Explain the importance of the Hepatic Portal Vein in the context of circulation.

Solution:

Intestine→Hepatic Portal VeinLiver→Hepatic Vein→Inferior Vena CavaIntestine \xrightarrow{Hepatic\ Portal\ Vein} Liver \rightarrow Hepatic\ Vein \rightarrow Inferior\ Vena\ Cava.

Explanation:

The Hepatic Portal Vein ensures that nutrients absorbed from the digestive tract are processed by the liver (detoxification, glucose regulation) before entering the general systemic circulation.

Double circulation - Revision Notes & Key Diagrams | CBSE Class 11 Biology