NCERT Solutions for Class 11 Biology Chapter 18 – Body Fluids and Circulation


Examinations can be intimidating. But with the help of the right resources, you can overcome your fears and face them confidently. NCERT solutions are one of the best tools to prepare for the exams, especially when it comes to Biology.

Chapter 18 in Biology for CBSE class 11 is about Body Fluids and Circulation. It is a part of the unit, Human Physiology.

NCERT Solutions for Class 11 Biology Chapter 18 – Body Fluids and Circulation

NCERT solutions help clear things up for students. The design is simple and easy to understand, as the chapters are logical. Chapter 18 discusses concepts related to the fluids that are present in the human body, their functions, and their circulation through the bloodstream. NCERT also gives questions at the end of the chapter. And the students can prepare for the exams by answering them.

You can download CBSE NCERT Solutions for Class 11 Biology  Chapter 18 from below.

Download NCERT Class 11 Biology Chapter 18 Solutions

What will you learn in Class 11 Biology Chapter 18 – Body Fluids and Circulation?

Body Fluids and Circulation is the 18th chapter in Biology for CBSE class 11. It has six concepts that talk about various aspects of the heart, blood, and the circulatory system.

Blood is a substance that mostly consists of plasma and other cellular material. Plasma is of straw color and is a viscous fluid that makes up for 55 percent of the blood. The blood has two major types of cells present in it, namely, the white blood cells and the red blood cells. While red blood cells live for about 120 days, white blood cells have a lifespan of only three or four days.

Red blood cells are the ones that carry the hemoglobin pigment, which gives the blood its color.

The chapter also talks about the human circulatory system that handles the flow of blood throughout the body. The primary organ of the human circulatory system is the heart. The heart pumps blood to the other parts of the body and has four parts. Two of them are the atria, and the other two are the ventricles.

The heart is a muscular organ that contracts and expands to function. And this contraction and expansion at regular intervals are known as the ‘cardiac cycle.’ The cardiac cycle consists of two phases, namely, the diastole and systole. During the diastole phase, the heart ventricles relax. Similarly, during the systole phase, they contract and pump blood into the arteries.

The autonomous nervous system controls the contraction and relaxation of the heart. When the heart contracts, the sympathetic nervous system acts to increase cardiac activity by increasing the heart rate and the strength of the ventricular contractions. Likewise, during the relaxation phase, the parasympathetic nervous system plays a prominent role in decreasing the heart rate and the strength of the ventricular contractions.

The normal diastolic pressure of the heart is 80 mm Hg, while the expected systolic pressure is 120 mm Hg. Also, when these two pressures cross 90 mm Hg and 140 mm Hg, respectively, the person suffers from Hypertension.

Similarly, when the arteries become narrow, a condition called coronary heart disease occurs. Coronary heart disease decreases the supply of blood to various other parts of the body.

If there is a clog in the heart, then it can lead to a cardiac arrest, where the heart ceases to function.

Benefits of NCERT Solutions for Biology Chapter 18

NCERT solutions offer a way for students to understand the concepts of chapter 18 in Biology, which talks about the heart and the circulatory system. You can find below various benefits of going through NCERT solutions for Biology Chapter 18.

1. Logical Flow

The chapter explains all the concepts logically so that the students will find it easier to understand them.

2. Designed by Experts

The teachers who design NCERT solutions are experts in Biology. So, they will be able to explain all the concepts concisely.

Thus, going through NCERT solutions for a subject like Biology, and especially for Chapter 18, which talks about the heart and the circulatory system, will increase your chances of scoring well in the exams. So, don’t forget to refer to the solutions when you sit down to study Biology.


We have covered the complete guide on CBSE NCERT Solutions for Class 11 Biology Chapter 18 – Body Fluids and Circulation. Feel free to ask us any questions in the comment section below.

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