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Have you ever thought about how oxygen and nutrients travel all through your body? The NCERT Class 11 Biology Chapter 15 Notes Body Fluids and Circulation explain this in a simple, easy-to-follow way. These notes include clear points, labelled diagrams, and solved questions so you can revise quickly without confusion. You will read about blood, lymph, the heart, blood vessels, and the double circulation system, all explained properly as per the NCERT book. These NCERT Notes also work well if you need a fast recap before board exams or NEET.
In these NCERT Class 11 Biology Notes of Chapter 15, you will find short, organised explanations of the structure of the heart, the working of valves, the cardiac cycle, and how blood pressure is controlled. Diagram suggestions are also included so you can improve how you present your answers. All points are set in order so you can go through them smoothly. Using these NCERT Notes for Class 11, students can build confidence in circulatory system topics and connect them with other chapters in human physiology.
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Having the notes in PDF format is beneficial because you can access them anytime without needing the internet. It helps you revise faster, stay organised, and keep all key points in one place. You can also read it on any device, highlight important terms, and go back to topics easily whenever needed. You can now download the NCERT Class 11 Biology Chapter 15 Notes Body Fluids and Circulation PDF for clear and quick exam preparation.
The chapter, Body Fluids and Circulation, helps you understand how blood and other fluids deliver oxygen and nutrients, and remove wastes to keep every part of your body working smoothly. It talks about the heart’s structure, blood vessels, the cardiac cycle, and even how the body defends itself, all explained in a simple, clear way. These Chapter 15 NCERT Notes also make tricky diagrams and key terms easier to remember, making them great for quick revision and for anyone looking for Class 11 Body Fluids and Circulation Notes PDF Download.
In living organisms, body fluids have an important role in the transportation of nutrients, gases, and waste products. Blood and lymph are the two principal body fluids in humans.
Blood is a specialized connective tissue that has critical functions, including the transport of oxygen, immunity, and homeostasis. It contains:
Lymph is a colourless fluid that is obtained from blood plasma. Unlike blood, it does not contain RBCs and contains less protein. Its roles are as follows:
Formed elements include erythrocytes (RBCs), leucocytes (WBCs), and platelets. They make up about 45% of blood volume.
Erythrocytes (Red Blood Cells, RBCs)
Leucocytes (White Blood Cells, WBCs)
The two categories of leucocytes are:
Granulocytes
Agranulocytes
Knowing a person’s blood group is important for safe blood transfusions, organ transplants, and even during pregnancy to avoid complications like hemolytic disease of the newborn. Blood groups are grouped based on the absence or presence of certain antigens on RBC surfaces. There are two major group systems:
Established by Karl Landsteiner, this is based on the presence of antigen A and antigen B on RBCs and plasma antibodies accordingly:
Blood circulation may take various forms based on the complexity of an organism.
The human heart is a four-chambered muscular organ in the thoracic cavity.
The cardiac cycle involves systole (contraction) and diastole (relaxation) for rhythmic blood flow. The normal heartbeat of a human is 72 beats a minute.
Three types of blood vessels transport blood:
Arteries: Carry oxygenated blood (except pulmonary artery) under high pressure.
Veins: Carry deoxygenated blood (except pulmonary vein) with valves to prevent backflow.
Capillaries: Facilitate gas and nutrient exchange at the tissue level.
The process of blood circulation is described as:
Blood Pressure and Pulse Rate
Regulation of Circulation by Hormones and the Nervous System
Some common circulatory disorders are:
1. High Blood Pressure (Hypertension)
2. Atherosclerosis
3. Stroke
4. Heart Attack (Myocardial Infarction)
Prevention and Lifestyle Changes
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Some of the questions which have come in past years from the chapter are given below:
Question 1. What would be the cardiac output of a person having 72 heartbeats per minute and a stroke volume of 50 mL?
Option 1. 360 mL
Option 2. 3600 mL
Option 3. 7200 mL
Option 4. 5000 mL
Answer :
The volume of blood the heart pumps in a minute is known as cardiac output, and it is measured in litres per minute. It makes sense that cardiac output is equal to the product of heart rate (the number of beats per minute) and stroke volume.
Cardiac output= Stroke volume X heart rate
=50X72
=3600mL
Hence, the correct answer is Option (2) 3600 ml
Question 2. Which of the following statements is incorrect?
Option 1. A person of ‘O’ blood group has anti ‘A’ and anti ‘B’ antibodies in his blood plasma.
Option 2. A person of ‘B’ blood group can’t donate blood to a person of ‘A’ blood group.
Option 3. Blood group is designated on the basis of the presence of antibodies in the blood plasma.
Option 4. A person of AB blood group is a universal recipient.
Answer :
Blood group is based on the presence or absence of antigens A and B on RBCs and presence or absence of two natural antibodies present in plasma.
Hence, the correct answer is the option (3) Blood group is designated on the basis of the presence of antibodies in the blood Plasma.
Question 3. Which of the following correctly explains a phase/ event in the cardiac cycle in a standard electrocardiogram?
Option 1. QRS complex indicates atrial contraction.
Option 2. QRS complex indicates ventricular contraction.
Option 3. The time between S and T represents atrial systole.
Option 4. P-wave indicates the beginning of ventricular contraction.
Answer :
Ventricular contraction is caused by the depolarization of the ventricles, which is represented by the QRS complex in a normal electrocardiogram (ECG/EKG).
The electrical signal that triggers the ventricular muscles' mechanical contraction is known as depolarization.
Because it causes blood to be pumped from the ventricles into the aorta and pulmonary artery, this stage of the cardiac cycle is crucial.
Hence, the correct answer is option 2) QRS complex indicates ventricular contraction.
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Here, students can find the notes of all chapters that explain all topics clearly and help in quick revision for exams.
Blood is composed of plasma (liquid component), red blood cells (RBCs), white blood cells (WBCs), and platelets. Plasma carries nutrients, RBCs transport oxygen, WBCs combat infection, and platelets assist in blood clotting.
The heart circulates oxygenated blood by arteries to the tissues of the body and collects deoxygenated blood via veins. The pulmonary circulation transmits gases within the lungs, whereas systemic circulation delivers oxygen to tissues.
Oxygen gets attached to hemoglobin in RBCs, making oxyhemoglobin. It is carried to tissues by arteries, and it is released for cellular respiration, whereas carbon dioxide is transported back to the lungs for expulsion.
The heart sends blood around the body through periodic contractions. It delivers oxygenated blood to tissues and carbon dioxide-laden blood to the lungs to be cleaned through pulmonary circulation.
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