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Biology · Class 11 Science

Ch 16Body Fluids and Circulation — Class 11 Biology, concept-first.

An adult human carries roughly five to five-and-a-half litres of blood, and this single fluid tissue is what connects every other tissue of the body to every other.

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Key concepts

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Blood Composition

Fluid connective tissue made of plasma and formed elements.

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Chapter contents

The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.

16.1

Blood — Plasma and Composition

An adult human carries roughly five to five-and-a-half litres of blood, and this single fluid tissue is what connects every other tissue of the body to every other.

16.2

Formed Elements — RBC, WBC and Platelets

Suspended within blood plasma are three structurally and functionally distinct kinds of formed element, and each is worth examining in turn, because in every case its structure is closely matched to t…

16.3

Blood Groups — the ABO and Rh Systems

Not every person's blood is chemically identical, and the differences matter enormously in medicine, particularly for safe blood transfusion.

16.4

Coagulation of Blood

Cutting or otherwise damaging a blood vessel must be dealt with quickly, since an animal with a closed, pressurised circulatory system can lose a dangerous volume of blood in a short time if the leak…

16.5

Lymph (Tissue Fluid)

Blood does not deliver its dissolved nutrients and gases directly to the cells of most tissues; instead, as blood flows through the network of capillaries, some of its plasma is continuously filtered…

16.6

Human Heart — Structure and Blood Vessels

The heart is the muscular pump that drives the entire circulation, roughly the size of its owner's closed fist, located in the thoracic cavity between the two lungs and tilted slightly towards the lef…

16.7

Cardiac Cycle

The cardiac cycle is the name given to the complete, repeating sequence of mechanical events that make up a single heartbeat — from the start of one contraction of the heart's chambers to the start of…

16.8

Cardiac Output and Electrocardiogram (ECG)

Cardiac output is the standard quantitative measure of how effectively the heart is actually pumping blood, and it is calculated from two simpler quantities that are each easy to measure or estimate o…

16.9

Double Circulation

The pattern of blood flow through the human body is described as double circulation, because for one complete round trip around the body, blood must actually pass through the heart twice — once throug…

16.10

Regulation of Cardiac Activity

Unlike skeletal muscle, which contracts only when it receives a nerve impulse originating from the brain or spinal cord, the heart is described as myogenic: the electrical impulse that initiates every…

16.11

Disorders of the Circulatory System

Because the circulatory system operates continuously throughout a person's entire life, without rest, it is also a system in which disorders are both common and clinically significant.

16.12

Summary — Body Fluids and Circulation

This chapter has traced body fluids and circulation from the level of individual formed elements to the working of the whole heart.

Very Short Answer Questions

+Show 8 questions8 questions
  1. Q11Name the fluid, non-cellular matrix of blood, and state the approximate percentage of blood volume it forms.Free
  2. Q12Name the three types of formed elements suspended in blood plasma.Free
  3. Q13Which blood group is referred to as the 'universal donor', and why?Free
  4. Q14Define lymph in one sentence.Preview
  5. Q15Name the two atrio-ventricular valves of the human heart and state which side of the heart each guards.Preview
  6. Q16What do the terms 'systole' and 'diastole' mean with reference to the cardiac cycle?Preview
  7. Q17Define cardiac output and give its normal approximate value (in litres per minute) at rest.Preview
  8. Q18Name any two disorders of the human circulatory system mentioned in this chapter.Preview

Short Answer Questions

+Show 9 questions9 questions
  1. Q19Distinguish between blood and lymph on the basis of composition, colour and the vessels they flow through.Free
  2. Q20Briefly describe the three types of formed elements of blood (RBC, WBC, platelets), stating one distinguishing structural feature and one fu…Free
  3. Q21Explain the basis of the ABO blood grouping system, naming the antigens and antibodies associated with each of the four blood groups.Free
  4. Q22What is the Rh factor? Briefly explain why Rh incompatibility is usually a concern only from the second Rh-positive pregnancy of an Rh-negat…Preview
  5. Q23Outline, in sequence, the main steps by which an injury leads to the formation of a blood clot.Preview
  6. Q24Sino-atrial node is called the pacemaker of the human heart. Why?Preview
  7. Q25What is the significance of the atrio-ventricular node and the atrio-ventricular bundle (bundle of His) in the conduction of the heartbeat?Preview
  8. Q26Briefly explain what hypertension is, and state why it is considered a risk factor for other circulatory disorders.Preview
  9. Q27Distinguish between angina pectoris and a heart attack (myocardial infarction) caused by coronary artery disease.Preview

Long Answer Questions

+Show 6 questions6 questions
  1. Q28Describe the composition of human blood in detail, covering the constituents of plasma and the structure, count and principal function of ea…Free
  2. Q29Describe the ABO and Rh blood grouping systems, and explain, with reasons, which blood group combinations are safe and which are unsafe for…Free
  3. Q30Describe, step by step, the mechanism of blood coagulation, explaining the roles of platelets, thromboplastin, prothrombin, thrombin, fibrin…Preview
  4. Q31Describe the structure of the human heart, including its chambers, septa, valves and the major blood vessels entering and leaving it, and ex…Preview
  5. Q32Define the cardiac cycle and describe its main phases (joint diastole, atrial systole and ventricular systole), explaining the origin of the…Preview
  6. Q33What is meant by double circulation? Describe the pulmonary and systemic circuits, explain how cardiac activity is regulated by the nodal sy…Preview

More questions

+Show 10 questions10 questions
  1. Q1Which plasma protein is chiefly responsible for maintaining the osmotic pressure (colloidal osmotic pressure) of blood that keeps water from…Free
  2. Q2A mature mammalian red blood cell (erythrocyte) is structurally unusual among vertebrate blood cells because it (a) Is nucleated and biconve…Free
  3. Q3Which type of white blood cell is normally the most numerous in a healthy person's blood and is the first to reach a site of infection, wher…Free
  4. Q4A person with blood group AB is called the 'universal recipient' because their plasma (a) Contains both anti-A and anti-B antibodies (b) Con…Preview
  5. Q5Erythroblastosis foetalis, a condition in which a foetus's red blood cells are destroyed by maternal antibodies, typically arises when (a) A…Preview
  6. Q6In the blood clotting cascade, the enzyme thrombin acts directly on which soluble plasma protein to convert it into the insoluble threads th…Preview
  7. Q7Lymph differs from blood plasma mainly in that lymph (a) Contains a higher concentration of plasma proteins (b) Contains no cells of any kin…Preview
  8. Q8The valve that lies between the right atrium and the right ventricle of the human heart, and which prevents the backflow of blood into the a…Preview
  9. Q9The heart is described as myogenic because (a) It requires a continuous nerve impulse from the brain to beat at all (b) The impulse for each…Preview
  10. Q10In a normal electrocardiogram (ECG), the QRS complex represents (a) Depolarisation (electrical activation) of the atria (b) Repolarisation o…Preview