15. Body Fluids and Circulation

Class 11 Biology Chapter 15 Body Fluids and Circulation

Chapter 15 Body Fluids and Circulation

Class 11 Biology Chapter 15 Body Fluids and Circulation Exercise Questions and Answers :

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

Answer : The formed elements in blood are the cellular components of blood that are suspended in the liquid portion, known as plasma.

There are three main types of formed elements in blood, each with distinct functions :

(a) Red Blood Cells (Erythrocytes) :

Function: Red blood cells are primarily responsible for transporting oxygen from the lungs to body tissues and organs, and they help carry carbon dioxide away from those tissues to the lungs for exhalation. This oxygen transport is facilitated by the iron-containing protein hemoglobin.

(b) White Blood Cells (Leukocytes) :

Function: White blood cells are a crucial part of the immune system. They help the body defend against infections and foreign invaders. There are several types of white blood cells, each with its own specific function in immune responses, including phagocytosis, antibody production, and the coordination of immune responses.

Function: Platelets play a vital role in blood clotting (coagulation). When there is a damaged blood vessel or injury, platelets adhere to the site, clump together, and help form a plug to stop bleeding. They also release various substances that promote clotting and tissue repair.

2. What is the importance of plasma proteins?

Answer : Plasma proteins, comprising albumins, globulins, and fibrinogen, play a crucial role in blood's functions. Albumins help maintain osmotic balance and regulate blood volume. Globulins are essential for immune defense. Fibrinogen is crucial for blood clotting. These proteins transport nutrients, waste products, and minerals and ensure blood remains a viable medium for various bodily functions. Their roles are vital for overall health and the maintenance of essential physiological processes.

3. Match Column I with Column II :

Column I	Column II
(a) Eosinophils	(i) Coagulation
(b) RBC	(ii) Universal Recipient
(c) AB Group	(iii) Resist Infections
(d) Platelets	(iv) Contraction of Heart
(e) Systole	(v) Gas transport

Answer : The match for Column I with Column II :

(a) Eosinophils--------- (iii) Resist Infections

(b) RBC --------- (v) Gas transport

(d) Platelets ---------- (i) Coagulation

(e) Systole ---------- (iv) Contraction of Heart

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

Answer : Blood is considered a connective tissue because it fulfills the primary characteristics of connective tissues. It consists of cells (red and white blood cells) suspended in an extracellular matrix (plasma). The matrix contains various proteins, such as fibrinogen and globulins, that help maintain its integrity. Blood connects different parts of the body, transporting oxygen, nutrients, hormones, and waste products to and from various tissues. Additionally, it plays a crucial role in immune response and wound healing, further emphasizing its connective nature in the body's overall structure and function.

5. What is the difference between lymph and blood ?

Answer : The differences between lymph and blood:

Lymph	Blood
Lymph is a clear, colorless fluid	Blood is a red, opaque fluid
Lymph is found in lymphatic vessels	Blood circulates in blood vessels
Lymph is derived from interstitial fluid that leaks from blood capillaries	Blood is a specialized bodily fluid produced by the circulatory system
Lymph contains white blood cells (lymphocytes), primarily	Blood contains red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
Lymph primarily serves as a part of the immune system, carrying white blood cells to sites of infection and draining excess fluid from tissues	Blood serves as a transport medium for oxygen, nutrients, waste products, hormones, and also plays a role in immune response, clotting, and maintaining homeostasis
Lymph does not transport oxygen	Blood is the primary medium for transporting oxygen through hemoglobin in red blood cells
Lymph does not contain clotting factors	Blood contains clotting factors (fibrinogen) necessary for coagulation

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

Answer : Double circulation is a circulatory system where blood flows through the heart twice in each complete circuit of the body. It is a vital characteristic of vertebrate circulatory systems and consists of two separate pathways are :

Pulmonary Circulation: Deoxygenated blood is pumped from the right ventricle of the heart into the pulmonary artery, which carries it to the lungs. In the lungs, the blood becomes oxygenated, and it returns to the left atrium of the heart via the pulmonary veins. This circuit serves the purpose of oxygenating the blood.

Systemic Circulation: Oxygenated blood is pumped from the left ventricle into the aorta, which distributes it to the entire body. The oxygenated blood travels through a network of arteries, arterioles, and capillaries, delivering oxygen and nutrients to body tissues and organs. Deoxygenated blood, loaded with carbon dioxide and waste products, returns to the right atrium via a system of venules, veins, and the superior and inferior vena cava. This circuit serves the purpose of nourishing the body's cells and removing waste products.

Significance of Double Circulation: Double circulation is significant because it effectively separates oxygenated and deoxygenated blood, ensuring that oxygen-rich blood is pumped to the body's tissues, while deoxygenated blood is sent to the lungs for oxygenation. This separation prevents the mixing of oxygenated and deoxygenated blood, which is essential for maintaining a high level of oxygen delivery to body tissues, particularly in warm-blooded animals like humans. It allows for efficient oxygen supply to body cells and supports metabolic functions while facilitating the removal of carbon dioxide and waste products. Additionally, this system enables the heart to maintain a continuous and robust supply of oxygen to meet the body's energy demands.

7. Write the differences between :

(a) Blood and Lymph

(b) Open and Closed system of circulation

(d) P-wave and T-wave

Answer : (a) The differences between Blood and Lymph :

Lymph	Blood
Lymph is a clear, colorless fluid	Blood is a red, opaque fluid
Lymph is found in lymphatic vessels	Blood circulates in blood vessels
Lymph is derived from interstitial fluid that leaks from blood capillaries	Blood is a specialized bodily fluid produced by the circulatory system
Lymph contains white blood cells (lymphocytes), primarily	Blood contains red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
Lymph primarily serves as a part of the immune system, carrying white blood cells to sites of infection and draining excess fluid from tissues	Blood serves as a transport medium for oxygen, nutrients, waste products, hormones, and also plays a role in immune response, clotting, and maintaining homeostasis
Lymph does not transport oxygen	Blood is the primary medium for transporting oxygen through hemoglobin in red blood cells
Lymph does not contain clotting factors	Blood contains clotting factors (fibrinogen) necessary for coagulation

(b) The differences between Open and Closed system of circulation :

Open Circulatory System	Closed Circulatory System
Hemolymph (a mix of blood and interstitial fluid) circulates through open spaces or sinuses, directly bathing the body tissues.	Blood circulates within a closed network of blood vessels, not directly in contact with body tissues.
Typically, an elongated tubular heart pumps hemolymph into the open spaces of the body.	A muscular, chambered heart pumps blood into a system of blood vessels.
Generally less efficient in transporting oxygen and nutrients because the hemolymph flows more slowly and has limited control over directing the flow.	More efficient in transporting oxygen, nutrients, and waste products because blood flows under pressure and can be selectively directed to specific body areas.
Oxygen and carbon dioxide exchange occurs directly between the hemolymph and body tissues.	Oxygen and carbon dioxide exchange primarily occurs in specialized respiratory organs, such as gills or lungs, and within capillaries.
Found in invertebrates, such as arthropods and mollusks.	Predominantly found in vertebrates, although some invertebrates (e.g., earthworms) have closed circulatory systems.
Relies on the pumping action of the heart and the body's movements for circulation.	Blood is actively pumped by the heart and is assisted by the muscular walls of blood vessels, which help maintain consistent flow.
Flow of hemolymph is not tightly regulated and can be influenced by external factors like body movements.	Blood flow is tightly regulated, allowing for precise control of circulation to different body regions and tissues.
Less efficient in transporting nutrients and removing waste products from tissues.	More efficient in transporting nutrients to cells and removing waste products, aiding in overall metabolism.

Systole	Diastole
The phase of the cardiac cycle when the heart muscles contract, specifically the ventricles.	The phase of the cardiac cycle when the heart muscles relax and chambers refill with blood.
During systole, the ventricles contract, pushing blood into the pulmonary artery and aorta.	During diastole, the heart chambers (atria and ventricles) relax, allowing them to fill with blood.
Blood is forcefully ejected from the ventricles into the aorta (systemic circulation) and the pulmonary artery (pulmonary circulation).	Blood is passively and actively drawn into the atria, and the ventricles begin to fill.
Blood pressure is at its highest during systole.	Blood pressure is at its lowest during diastole.
The first heart sound ("lub") occurs during systole, corresponding to the closure of the atrioventricular (AV) valves.	The second heart sound ("dub") occurs during diastole, marking the closure of the semilunar valves.
Systole is a relatively short phase compared to diastole, typically lasting about one-third of the cardiac cycle.	Diastole is a longer phase, constituting about two-thirds of the cardiac cycle.
Systole is responsible for pumping oxygenated blood into the systemic circulation (left ventricle) and the pulmonary circulation (right ventricle).	Diastole allows the heart chambers to refill with blood, preparing them for the next contraction (systole).
The electrical depolarization of the ventricles (QRS complex) occurs during the early part of systole, initiating ventricular contraction.	The electrical repolarization of the ventricles (T wave) occurs during diastole, signaling the relaxation phase of the heart.

(d) The differences between P-wave and T-wave :

P-wave	T-Wave
The P-wave is the first deflection on an ECG, typically a small, upright wave.	The T-wave is the second major wave on an ECG, following the QRS complex. It is typically an upright or slightly inverted wave.
The P-wave represents atrial depolarization, signifying the contraction of the atria.	The T-wave represents ventricular repolarization, signifying the relaxation of the ventricles.
The P-wave is generated by the spread of an electrical impulse through the atria, causing them to contract.	The T-wave results from the repolarization of ventricular cells, indicating the end of the ventricular contraction phase.
Changes in the P-wave can indicate atrial arrhythmias or conduction abnormalities.	Changes in the T-wave can signal various cardiac conditions, including ischemia, electrolyte imbalances, and certain medications' side effects.
The P-wave reflects atrial function and the initiation of the cardiac cycle.	The T-wave reflects the ventricular repolarization phase, which allows for ventricular relaxation and refilling with blood.

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

Answer : The evolutionary changes in the pattern of the heart among vertebrates are closely linked to the transition from open circulatory systems to closed circulatory systems, leading to increasingly efficient blood circulation.

Fishes (2-Chambered Heart) : Fishes have a relatively simple, two-chambered heart consisting of an atrium and a ventricle. The heart pumps deoxygenated blood to the gills for oxygenation and then distributes oxygenated blood to the body. This is an example of single circulation, with blood passing through the heart once per circuit.

Amphibians and Most Reptiles (3-Chambered Heart) : Amphibians and most reptiles have evolved to have a three-chambered heart with two atria and a single ventricle. Oxygenated blood from the lungs or skin is returned to the left atrium, while deoxygenated blood from the body is returned to the right atrium. However, the mixing of oxygenated and deoxygenated blood occurs in the single ventricle, representing incomplete double circulation.

Crocodiles, Birds, and Mammals (4-Chambered Heart) : These groups have developed four-chambered hearts with two atria and two ventricles. Oxygenated blood is sent to the body through the left ventricle, and deoxygenated blood is sent to the lungs (or in the case of birds, both lungs and air sacs) through the right ventricle. This complete separation of oxygenated and deoxygenated blood is a hallmark of double circulation, which ensures that highly oxygenated blood is distributed to the body tissues.

The transition from two-chambered to four-chambered hearts represents an evolutionary adaptation toward greater efficiency in oxygen delivery, enabling vertebrates to occupy a wider range of ecological niches and exhibit a diverse array of lifestyles. Double circulation, as seen in crocodiles, birds, and mammals, is highly advantageous for maintaining high metabolic demands and precise oxygen control.

9. Why do we call our heart myogenic ?

Answer : The human heart is referred to as "myogenic" because it possesses a specialized musculature known as nodal tissue. This tissue, particularly the sinoatrial node (SAN), has the remarkable ability to generate electrical impulses or action potentials spontaneously without any external stimuli. The SAN, often called the pacemaker, initiates and maintains the rhythmic contractile activity of the heart, leading to its myogenic nature. This intrinsic ability to generate its own electrical impulses allows the heart to maintain a continuous and coordinated heartbeat independently.

10. Sino-atrial node is called the pacemaker of our heart. Why?

Answer : The sinoatrial node (SAN) is labeled the "pacemaker" of the heart because it has the unique ability to generate electrical impulses spontaneously, without external stimuli. It exhibits the fastest firing rate among nodal tissues in the heart, producing around 70-75 impulses per minute. These electrical signals initiate and regulate the heartbeat, coordinating the contractions of the atria and ventricles. The SAN's consistency and reliability in setting the heart's rhythm make it the primary initiator of the cardiac cycle and ensure effective blood circulation.

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

Answer : The atrioventricular (AV) node and atrioventricular (AV) bundle are crucial components of the heart's electrical conduction system. The AV node delays electrical signals, allowing the atria to contract before the ventricles, ensuring efficient blood pumping. It also serves as a backup pacemaker. The AV bundle rapidly transmits signals from the AV node, coordinating ventricular contractions. Together, these structures regulate the heart's rhythm and synchronization, enabling the efficient circulation of blood throughout the body. Dysfunction in these components can lead to arrhythmias and compromise cardiac function.

12. Define a cardiac cycle and the cardiac output.

Answer : The cardiac cycle is a rhythmic sequence of events that occurs during each heartbeat, lasting approximately 0.8 seconds. It comprises systole (contraction) and diastole (relaxation) phases of both atria and ventricles. The heart undergoes atrial systole, followed by ventricular systole, during which the tricuspid and bicuspid valves close, forcing the semilunar valves open, allowing blood to be ejected into the pulmonary artery and aorta. The cardiac cycle results in the ejection of approximately 70 mL of blood from each ventricle per beat, known as stroke volume. Cardiac output, defined as the volume of blood pumped by each ventricle per minute, is determined by multiplying the stroke volume by the heart rate.

In healthy individuals, the cardiac output averages 5 liters per minute but can vary with factors like physical fitness. During the cardiac cycle, the closing of heart valves produces two audible sounds: the first heart sound (lub) when the tricuspid and bicuspid valves close, and the second heart sound (dub) when the semilunar valves close. These sounds are of clinical significance for heart diagnostics.

13. Explain heart sounds.

Answer : Heart sounds are the audible manifestations of cardiac events during each cardiac cycle. The first heart sound (lub) is generated when the tricuspid and bicuspid valves close at the beginning of ventricular contraction. The second heart sound (dub) is produced by the closure of the semilunar valves as ventricular ejection concludes. These sounds are critical for clinical diagnosis, helping healthcare professionals assess the heart's function and detect abnormalities.

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

Answer : An ECG (electrocardiogram) is a graphical representation of the heart's electrical activity during a cardiac cycle. To obtain a standard ECG, electrodes are placed on a patient's body, with three leads connected to the wrists and left ankle. The ECG waveforms consist of several segments:

Diagrammatic representation of a standard EGG

(a) P-Wave: This represents the electrical excitation (or depolarization) of the atria, leading to atrial contraction. It is the first positive deflection on the ECG.

(b) QRS Complex: This complex indicates the depolarization of the ventricles, initiating ventricular contraction. It consists of three distinct waves:

(i) Q-Wave: The initial downward deflection.

(ii) R-Wave: The sharp, positive peak.

(iii) S-Wave: The following downward deflection.

(c) T-Wave: This represents the repolarization of the ventricles, signaling the return to their normal state. The T-wave is a positive deflection and marks the end of systole.

The ECG allows clinicians to assess the heart's electrical activity and diagnose abnormalities or diseases based on deviations from the standard waveform shape. The number of QRS complexes in a given time period is used to determine an individual's heart rate.