NCERT Solutions for Class 11 Biology Chapter 15 Body Fluids and Circulation

Question 1. Name the components of the formed elements in the blood and mention one major function of each of them.

Answer:

The following formed elements were discovered in the blood:

(1) Erythrocytes: The most prevalent type of red blood cells, erythrocytes are coloured red by the red pigment known as haemoglobin. Every part of the body receives oxygen from erythrocytes. Some body parts, like the marrow of long bones, ribs, etc., continuously produce these. Each cubic millimetre of blood contains roughly 4–6 million red blood cells.

(2) Leukocytes: These are colourless cells devoid of haemoglobin. They fall into two major categories and are the largest cells in the body.

(a) Granulocytes- These leukocytes have granules in their cytoplasm and include neutrophils, eosinophils, and basophils. Neutrophils are phagocytic cells that protect the body against various infecting agents. Eosinophils are associated with allergic reactions, while basophils are involved in inflammatory responses.

(b) Agranulocytes- Lymphocytes and monocytes are agranulocytes. Lymphocytes generate immune responses against infecting agents, while monocytes are phagocytic in nature.

(3) Platelets- These are small irregular bodies present in the blood. They contain essential chemicals that help in clotting. The main function of platelets is to promote clotting.

Question 2. What is the importance of plasma proteins?

Answer:

About 55% of blood is made up of plasma, the colourless fluid. It facilitates the transportation of waste materials, salts, food, and carbon dioxide, among other things. Proteins like albumins, globulins, and fibrinogens make up around 6.8% of plasma. The liver produces the plasma glycoprotein fibrinogen. It contributes to blood coagulation. One of the main proteins in plasma, globulin, shields the body from pathogens. One of the main proteins in plasma that keeps the fluid volume in the vascular space constant is albumin.

Question 3. Match Column I with Column II :

Answer:

The correct matching is a- iii, b- v, c- ii, d-i, e- iv

Question 4. Why do we consider blood as a connective tissue?

Answer:

For the following reasons, we view blood as connective tissue:

• The body's other organs are held together, connected, or supported by connective tissues.
• They are the body's most prevalent and plentiful tissue.
• Gases, nutrients, and hormones are all transported by blood between the body's organs.
• It circulates throughout the body.
• Blood is, therefore, regarded as connective tissue.
  
  

Question 5. What is the difference between lymph and blood?

Answer:

Blood

• Blood is a red colour connective tissue.
• It consists of hemoglobin, red blood cells, white blood cells, and platelets. It circulates via arteries, veins, and capillaries.
• Blood transports gases and nutrients to various parts of the body.

Lymph

• Lymph is a white-coloured fluid in the body.
• It has white blood cells known as lymphocytes and flows through vessels called lymph.
• The lymph system facilitates the interchange of gases and nutrients between the body's cells and blood.

Question 6. What is meant by double circulation? What is its significance?

Answer:

Double circulation occurs when blood flows through the heart twice in a single cycle. Although it can be found in birds, mammals, amphibians, and reptiles, it is most noticeable in birds and mammals because of their four-chambered hearts:

• Atrium on the right
• The right ventricle
• Atrium on the left
• The left ventricle

The circulation of blood is separated into:
Systemic circulation: Blood that has been oxygenated leaves the left ventricle and travels to the aorta, then passes through arteries to reach bodily tissues before returning to the right atrium as deoxygenated blood.
Pulmonary circulation: Blood that has lost oxygen travels from the right ventricle to the lungs for oxygenation before returning to the left atrium.
By separating oxygenated and deoxygenated blood, double circulation guarantees an effective oxygen supply.

Question 7. (1) Write the differences between Blood and Lymph

Answer:

Question 7. (2) Write the differences between Systole and Diastole

Answer:

Systoles:

• It is the heart's chambers contracting.
• It raises the heart's internal blood pressure.
• When the chambers are in systole, blood is pumped out.

Diastole:

• It is the heart's chambers relaxing.
• The heart's blood pressure drops.
• The chambers in diastole receive blood.

Question 7. (3) Write the differences between P-wave and T-wave

Answer:

P-Wave:

1. P-wave represents the depolarisation or electrical excitation of atria.
2. Blood is pumped into the ventricles.

T-Wave

1. T-wave represents the repolarization of ventricles.
2. Blood is received by the atria.

Question 8. Describe the evolutionary change in the pattern of heart among the vertebrates.

Answer:

• In vertebrates, the heart has changed from having two chambers in fish to having four chambers in mammals and birds.
• In fish, deoxygenated blood is pumped to the gills for oxygenation by the heart's two chambers.
• Amphibians have three chambers, a ventricle, two atria, and a mixture of oxygenated and deoxygenated blood in the ventricle.
• In reptiles, blood mixing is decreased by an incomplete septum.
• The four-chambered hearts of crocodiles, birds, and mammals guarantee that oxygenated and deoxygenated blood are completely separated.

This development increases the availability of oxygen and effectively controls blood flow.

Question 9. Why do we call our hearts myogenic?

Answer:

Because the cardiac impulse starts in the heart's muscles, the organ is known as myogenic. The heart beats as a result of impulses produced by the SA node, a specialized cardiac tissue, spreading throughout the heart walls.

"Genic" means coming from, and "myo" means muscle.

Question 10. The sino-atrial node is called the pacemaker of the heart. Why?

Answer:

The sino-atrial node is referred to as the heart's pacemaker due to its ability to generate a cardiac impulse. The cardiac impulse and action potential are produced by the sinoatrial node. The atria and ventricles then contract or relax as a result of this cardiac impulse spreading throughout them.

The maximum number of action potentials that the SA node can produce is roughly 70–75 per minute. It also regulates the heart's rhythmic contractions.

Question 11. What is the significance of the atrio-ventricular node and the atrio-ventricular bundle in the functioning of the heart?

Answer:

The atrioventricular node and atrioventricular bundle are important for the heart's operation because:

• The SA node sends the cardiac impulse to the atrioventricular node.
• The cardiac impulse is sent farther toward the ventricle walls by the atrioventricular bundle, which emerges from the AV node.

Question 12. Define the cardiac cycle and the cardiac output.

Answer:

The cardiac cycle

• The alternating contraction and relaxation of the heart chambers, which is also referred to as diastole and systole, is what causes the blood to circulate in the heart.
• There is a relaxation or expansion phase (diastole) after each contraction phase (systole).
• The cardiac cycle, which lasts 0.8 seconds, is the sequence of events that take place during a single heartbeat.
  Heart Output
• The cardiac output is the volume of blood pumped by each ventricle in a minute.

Question 13. Explain heart sounds

Answer:

Every heartbeat is followed by a series of heart sounds.

• Every cardiac cycle produces the sounds "lub" and "dub."
• The first low-pitched sound, "lub," is produced when the tricuspid and bicuspid valves close.
• The second high-pitched sound, "dub," is produced when the semi-lunar valves close.
• For the diagnosis of heart-related conditions, these sounds are important.

Question 14. Draw a standard ECG and explain the different segments in it.

Answer:

The heart's activity during a cardiac cycle is represented graphically by an ECG. Electrocardiograph, or ECG. Assume that a patient has three electrical leads attached to the device—one to the left ankle and one to each wrist—and that the device is continuously monitoring the patient's heart activity. Several leads are connected to the chest area for a thorough assessment of the heart's performance.

Every ECG peak is denoted by a letter, ranging from P to T, which represents a distinct electrical activity of the heart.

The P-wave is a representation of the electrical excitation (or depolarisation) of the atria, which causes both atria to contract.

The QRS complex stands for the ventricles' depolarisation, which starts the ventricular contraction. Shortly after, the contraction begins.

T-wave symbolises the ventricles' repolarisation or transition from an excited to a normal state.

The systole ends when the T-wave ends. Naturally, one can calculate a person's heartbeat rate by counting the number of QRS complexes that occur in a specific amount of time. For a given lead configuration, the ECGs from different people have a similar shape, so any deviation from this shape suggests a potential abnormality or illness. It is, therefore, very important from a clinical standpoint.