Karnataka 1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

1st PUC Biology Body Fluids and Circulation One Marks Questions and Answers

Question 1.
What type of blood is carried by the pulmonary artery?
Answer:
Deoxygenated blood.

Question 2.
Name the artery that supplies blood to the heart muscle.
Answer:
Coronary artery

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 3.
Where does the stimulus for heart beat, originate in humans?
Answer:
In the Sino Atrial Node (SAN).

Question 4.
What is myocardial infarction?
Answer:
It is the death of the myocardial tissue due to the interrupted blood supply

Question 5.
Name the veins which bring oxygenated blood to heart.
Answer:
Pulmonary veins.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 6.
What is a pacemaker? Give an example.
Answer:
It is the structure which sets the pace for the initiation and regulation of the heart beat.
e,g: Sino Atrial Node.

Question 7.
Masse the components -of the conducting system in human heart.
Answer:
Sino atria node, atrioventricular node, bundle of HIS and parkinje fibres.

Question 8.
Why is the left ventricular valve thicker than the right-ventricular valve?
Answer:
To pump the oxygenated’ blood by powerful contraction through out the body.

Question 9.
Name the modern instrument used to record blood pressure.
Answer:
Sphygmomanometer

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 10.
Why m the human heart calks a double pump?
Answer:
Because the heart pumps both the oxygenated and deoxygenated bloods separately.

Question 11.
When do you designate a person as hypertensive?
Answer:
When the diastolic blood pressure is more than 90 mm of Hg.

Question 12.
Name the blood component which is viscous and straw coloured fluid.
Answer:
Plasma.

Question 13.
Name the vascular connection that exists between the digestive tract and liver.
Answer:
Hepatic portal vein.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

1st PUC Biology Body Fluids and Circulation Two Marks Questions and Answers

Question 1.
Why is human blood circulation considered complete?
Answer:
Human blood circulation is considered complete because, it has both systemic and pulmonary circulation. It is a double circulation. The right half receives and pumps deoxygenated blood and the left half receives and pumps oxygenated blood as separate activities.

Question 2.
What is meant by complete double circulation?
Answer:
In the cardio-vascular system the human heart works like a double pump. The right half receives and pumps deoxygenated blood and the left half receives and pumps oxygenated blood separately. It involves shorter pulmonary circulation and a longer systemic circulation.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 3.
Explain pulmonary circulation.
Answer:
It includes the collection of deoxygenated blood into the right chambers of the heart and then pumping the same to the lungs for oxygenation, and bringing back the oxygenated blood from the lungs into the left atrium.

The superior venacava and inferior venacava collect the deoxygenated blood into the right atrium from anterior and posterior regions of the body respectively. Then it is pumped into the right ventricle. This in turn, pumps it to the lungs, through the pulmonary artery for purification. The oxygenated blood leaves the lungs through pulmonary veins which open into the left atrium.

Question 4.
Explain systemic circulation.
Answer:
It includes the collection of oxygenated blood into left chambers of the heart, and the distribution of the same to various tissues through aorta, and its branches.

A set of four pulmonary veins bring the oxygenated blood from lungs into the left atrium. The left atrium pumps the oxygenated blood into the left ventricle which shows powerful contractions. So the blood is pumped into the aorta under a definite pressure.

Aorta gives off various branches in different directions for distribution. The blood exchanges oxygen, and carbon dioxide in the tissues of the body. Thus the blood is again deoxygenated. This deoxygenated blood is collected by superior and inferior venacava and sent into the right atrium.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 5.
Mention any four functions of blood.
Answer:

  • Blood transports food molecules and oxygen to various tissues.
  • Removes CO2 and the nitrogenous wastes from the tissue, and transports them to lungs and kidneys repsectively.
  • Maintains the constant temperature of the body.
  • Protects body by producing antibodies and ingesting pathogens.
  • Also carries hormones, and vitamins to various organs.

Question 6.
What is the importance of plasma proteins?
Answer:
Plasma has about 70 types of proteins which include Serum albumins, Serum goblins, Fibrinogen, Prothrombin, Lysozyme and Properdin.

Functions :
1. Prothrombin and fibrinogen are involved in blood clotting.
2. Acts as a protein reserve and can enter cells in case of protein shortage.
3. Immunoglobulins and lysozyme are extensive in function.
4. Maintain the viscosity of blood.

Question 7.
Why do we consider blood as a connective tissue?
Answer:
As it connects and supports different structures of animal body.

Question 8.
What is the difference between lymph and blood?
Answer:
Lymph:
It is a colourless mobile fluid or vascular connective tissue which flows in vessels called lymph vessels. Lymph is derived from intersitial or tissue fluid by means of fine, blind and iregular lymph capillaries. It is ultimeately drained into venous blood.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Blood: It is a fluid tissue consisting of,
1. Plasma.
2. Corpuscles or cells.
1. Plasma : It is a straw yellow (almost colourless) homogenous matrix containing large amount of water (about 90%). A number of gases (O2, CO2) and substances are dissolved in it. Plasma also carries metabolic wastes, hormones, antibodies, etc. Plasma is the matrix and blood corpuscles are suspended it.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.1
2. Blood corpuscles: They are of 3 types. namely

  • Erythrocytes or RBCs (Red Blood conpuscles).
  • Leucocytes or WBCs (White Blood conpuscles).
  • Platelets.

Question 9.
What is meant by double circulation? What is its significance?
Answer:
Double circulation :
1. Human heart acts like a double pump.
2. The right side of the heart receives, and pumps deoxygenated blood and the left side of the heart receives and pumps oxygenated blood and hence both the routes are kept completely separate and there is no mixing of oxygenated and deoxygenated blood. This type of circulation is said to be complete double circulation.
3. Double circulation involves shorter pulmonary circulation, and longer systematic circulation.

Question 10.
Why do we call our heart myogenic?
Answer:
Myogenic heart — In this type of heart a specialised muscular node namely Sino Atrial Node (SAN) present in tite wall of the right atrium, is the pacemaker which generates electrical impulses. e.g. Myogenic heart is present in vertebrates and molluscans.

Question 11.
Sino-atrial node is called the pacemaker of our heart. Why?
Answer:
In human beings the heart beat is initiated by a special group of muscles called Sino Atrial Node (SAN) present at the upper part of the right auricle. The SAN is also known as pacemaker of the heart because it initiates the electrical impulses for the heart beat.

The SAN produces the electrical impulses which start a series of muscular contractions. The electrical impulses pass through the auricular muscles, and as a result hence auricles contract. Subsequently the impulses are passed on to the ventricles by the node (AVN).

The bundle of his, divides into two branches-the right and left bundles. The HIS bundle is further divided into Purkinje system of fibers in the walls of the ventricles. The his bundle and its branches conduct the electrical impulses to ventricle muscles. Thus of his bundle constitutes the conducting system.

As a result of this, the ventricle contracts at the same time. This is known as ventricular systole. This results in the pumping of blood through the aorta, and pulmonary artery.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 12.
What is the significance of atrio-ventricular node and art io-ventricular bundle in the functioning of heart?
Answer:
Based on the nature of pacemaker there are two types of heart, namely.
1. Myogenic heart — In this type of heart a spec ialised muscular node namely Sino Atrial Node (SAN) present in the wall of the right atrium, is the pacemaker which generates electrical impulses. e.g. Myogenic heart is present in vertebrates and molluscans.

2. Neurogenic heart: In this type of heart a, group of nerve cells present on the dorsal surface of heart acts as pacemaker. It is called cardiac ganglion. e.g. in arthropods, neurogenic heart is present.

Question 13.
Define a cardiac cycle and the cardiac output.
Answer:
Cardiac cycle (Heart Beat):
The sequential cyclic events of systole (contraction state) and diastole (relaxation state) together are known as one cardiac cycle or heart beat.

In a healthy person, the heart completes 72beats/min. On an average, each complete heart beat requires 0.8 sec in which systole of ventricles require 0.3 sec, systole of auricles require 0.1 sec, diastole of the heart requires 0.4 sec.

Cardiac Output:
The amount of blood pumped by the right and left Ventricles per minute, is known as cardiac output. It is determined by multiplying the stroke volume with number of heart beats/mm.
Cardiac Output = stroke volume x number of heart beats / minute
= 70 ml x 72 beats / min
= 5040 ml of blood.

Question 14.
Draw a standard ECG and explain the different segments in it.
Answer:
ECG has 5 waves or deflections which are conventionally designated as PQRST. The five waves have a horizontal part in the beginning as well as inside. It is called isopotential or baseline. PR, and T waves lie above the horizontal line. They are called positive waves. Q and S waves lie below the horizontal line, arid are therefore called negative waves. P represents the development of action potential at the sinoatrial node, and the spread of impulse throughout the atria. The atrial muscles become depolarized.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

After a fraction of a second, the next complex of QRS begins with a small downward or negative reflection of Q. QRS represents depolarisation of atrial muscles and depolarisation of ventricular muscles. Its different components are PQ, QR and RS. PQ indicates contraction of atria. QR provides information

about spread of cardiac impulse from SA node to AV node. RS gives information about pread of impulse from AV node to Purkinje fibers, and ventricular depolarization. It initiates contraction of ventricles. Ventricular contraction continues during ST part. It is followed by the relaxation of ventricles and development of the repolarisation wave.

Question 15.
Given below are abnormal conditions related to blood circulatory system.
Name the disorders :
(a) Acute chest pain due to failure of O2 supply to heart muscles
(b) Increased systolic pressure.
Answer:
(a) Angina
(b) Hypertension.

Question 16.
Which coronary artery disease is caused due to the narrowing of the lumen of arteries?
Answer:
Coronary artery disease (CAD) due to atherosclerosis leading to ischemic heart disease.

Question 17.
Define the following terms, and give their location : (a) Purkinje fibres (b) Bundle of HIS.
Answer:
(a) Purkinje Fibres : They are special large-sized impulse conducting muscle fibres present in AV bundle, its branches, and their terminal strands.

(b) Bundle of HIS (AV Bundle): It is a bundle of conducting muscles which develop from AV node, pass through the atrioventricular septum and come into ventricular region to divide into right and left bundle branches.

1st PUC Biology Body Fluids and Circulation Three Marks Questions and Answers

Question 1.
Name the components of the formed elements in the blood, and mention one major function of each of them.
Answer:
Eosinophils: They constitute 2 to 4 % of the leucocytes. i.e., their number ranges from 180 – 360/mm3 of blood. They are characterised by the presence of coarse cytoplasmic granules that stain deep red with acidic stain like Eosin. The nucleus is bilobed. They produce antihistamines that destroy antigen – antibody, and combat against irritants causing allergy.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.3

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Question 2.
Write the differences between:
(a) Blood and Lymph
Answer:
Lymph:
It is a colourless mobile fluid or vascular connective tissue which flows in vessels called lymph vessels. Lymph is derived from intersitial or tissue fluid by means of fine, blind and iregular lymph capillaries. It is ultimeately drained into venous blood.

Blood: It is a fluid tissue consisting of,
1. Plasma.
2. Corpuscles or cells.
1. Plasma : It is a straw yellow (almost colourless) homogenous matrix containing large amount of water (about 90%). A number of gases (O2, CO2) and substances are dissolved in it. Plasma also carries metabolic wastes, hormones, antibodies, etc. Plasma is the matrix and blood corpuscles are suspended it.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.1
2. Blood corpuscles: They are of 3 types. namely

  • Erythrocytes or RBCs (Red Blood conpuscles).
  • Leucocytes or WBCs (White Blood conpuscles).
  • Platelets.

(b) Open, and Closed system of circulation
Answer:
Open Circulatory System: Is the system that is primarily found in invertebrates. Here, the blood flows freely through cavities and there are no vessels to conduct the blood.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Closed Circulatory System: Is the system that is found in vertebrates and a few invertebrates like earthworms. This system In the presence of vessels conducts blood throughout the body.

(c) Systole, and Diastole
Answer:
The force of the blood against the walls of the blood vessels creates a pressure known as blood pressure. The B.P. is maximum during the ventricular systole. It is called systolic B.P (SBP). The B.P. is minimum during ventricular diastole. It is called diastolic B.P (DBP).

The B.P is measured by an instrument called sphygmomanometer invented by Stephen Hales.

The systolic pressure in a normal person is 120 mm of Hg, and diastolic pressure is about 80mm of Hg. Therefore the normal BP can be written as

The difference between systolic and diastolic pressure is called pulse pressure. Its averages is about 40 mm of Hg. [120-80=40mm of Hg]. In normal human adults systolic pressure may go up to 150 mm of Hg, and diastolic BP may vary from 60-80 mm of Hg.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

(d) P-wave, and T -wave
Answer:
P wave represents the development of action at Sino atrial node, and spread of impulse throughout atria. The atrial muscles become depolarized. A small downward or negative detection after p-wave is Q.wave.

Question 3.
Explain heart sounds.
Answer:
Each heart beat consists of two sounds.
1. First sound is Lub. It is loud low pitched and lasts for about 0.16 second. It is produced due to the closure of bicuspid and tricuspid valves during ventricular systole.
2. Second sound is called dub. It has a higher pitch and lasts for about 0.10 second. It is produced due to the closure of pulmonary and aortic semi lunar valves during ventricular diastole.

1st PUC Biology Body Fluids and Circulation Five Marks Questions and Answers

Question 1.
Explain the histology of the blood.
Answer:
Blood circulation:
The movement of blood through a system of blood vessels and heart is known is Blood circulation. The Blood circulation was discovered by William Harvey in 1668.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

(a) Blood: It is a fluid tissue consisting of,
1. Plasma.
2. Corpuscles or cells.
1. Plasma: It is a straw yellow (almost colourless) homogenous matrix containing large amount of water (about 90%). A number of gases (O2, CO2) and substances are dissolved in it. Plasma also carries metabolic wastes, hormones, antibodies, etc. Plasma is the matrix and blood corpuscles are suspended in it.

2. Blood corpuscles: They are of 3 types. namely
(i) Erythrocytes or RBCs (Red Blood conpusc les).
(ii) Leucocytes or WBCs (White Blood conpuscles).
(iii) Platelets.
(i) Erythrocytes: They are circular in outline but look like biconcave from sideview. In mammals RBCs are enucleate upon maturation (except those of the family Camellidae). Cytoplasm includes haemoglobin, the iron pigment.

b. (WBC.Granulocyte)
Haemoglobin has greater affinity for O2. Thus RBCs transport O2 Surface view Surface view to various tissues. The number of RBCs is about 5 million per cubic mm of blood. They have a short life span of about 120 days.

Question 2.
Describe the origin and conduction of heart beat.
Answer:
In human beings the heart beat is initiated by a special group of muscles called Sino Atrial Node (SAN) present at the upper part of the right auricle. The SAN is also known as pacemaker of the heart because it initiates the electrical impulses for the heart beat.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

The SAN produces the electrical impulses which start a series of muscular contractions. The electrical impulses pass through the auricular muscles, and as a result hence auricles contract.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.9
Subsequently the impulses are passed on to the ventricles by the node (AVN). The bundle of HIS, divides into two branches-the right and left bundles. The HIS bundle is further divided into Purkinje system of fibers in the walls of the ventricles. His bundle and its branches conduct the electrical impulses to ventricle muscles. Thus the of His bundle constitutes the conducting system. As a result of this, the ventricle contracts at the same time. This is known as ventricular systole. This results in the pumping of blood through the aorta, and pulmonary artery.

Question 3.
Explain Circulation in humans.
Answer:
Circulation in human beings was discovered by William Harvey. In the cardio vascular system human heart works like a double pump. The right half receives and pumps deoxygenated blood and the left half receives and pumps oxygenated blood. This type of circulation is called circulation and it involves a shorter pulmonary circulation and a long systemic circulation.

1. Pulmonary circulation : It includes collection of deoxygenated (impure) blood into the right side chambers of the heart. Then pumping the same into lungs for oxygenation and bringing back the oxygenated blood from the lungs into the left atrium.

The superior vena cava and inferior vena cava, collect the impure blood into the right atrium from anterior and posterior regions of the body respectively. Now, it is pumped into the right ventricle. This in turn pumps the blood to the lungs through the pulmonary artery.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Blood exchanges carbon dioxide for oxygen in the capillaries of the alveoli. Thus the blood gets oxygenated. The purified blood leaves the lungs through pulmonary veins, which open into left atrium. So the left atrium receives pure blood from the lungs.

2. Systemic circulation: This includes collection of oxygenated blood into the left chamber of the heart and the distribution of the same among the various tissues of different organs through aorta and its branches.
A set of four pulmonary veins bring the oxygenated blood from lungs into the left atrium. The left atrium pumps the oxygenated blood into the left ventricle, which shows powerful contractions.

Blood is pumped into aorta with a definite pressure. Aorta gives off various branches in different regions for the distribution. Blood exchanges oxygen for carbon dioxide in the tissues of the body. Thus blood is again deoxygenated. This deoxygenated blood is collected by superior venacava and inferior venacava and poured into right atrium.

Question 4.
Draw a neat labelled diagram of V.S. of human heart.
Answer:
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.11
Question 5.
Describe the anatomy of human heart.
Answer:
(a) Heart chambers: The human heart is typically four chambered. The upper chambers are called auricles or atria. The lower chambers are called ventricles. The walls of the auricles are thin, whereas the walls of the ventricles are thick. The auricles are separated . by inter auricular septum. Ventricles are separated by inter ventricular septum, whereas the auricles and ventricles are separated by auriculo ventricular septum.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

(b) Blood vessels associated with the heart : Two large veins called superior vena cava and inferior vena cava come together and form sinus venosus. This in turn opens into the right atrium. Two pairs of pulmonary veins (a pair from each lung) open separately into left atrium from lungs.

The pulmonary artery arises from the right ventricle, and divides into two branches just above the heart. The largest artery called aorta arises from the left ventricle and runs upward-turns to the left and runs posteriorly as dorsal aorta.

(c) Valves of the heart: Various types of valves are present at various openings to check the backward flow of blood. The left atrio-ventricular opening is guarded by two flap like structures called bicuspid valve. The free edges (cusps) of these valves are attached to the walls of the ventricles by “Chordae tendinae”. The opening of pulmonary artery into the right ventricle, and the opening of aorta into the left ventricle are guarded by semilunar valves.

1st PUC Biology Body Fluids and Circulation Text Book Questions and Answers

Blood circulation:
The movement of blood through a system of blood vessels and heart is known is Blood circulation. The Blood circulation was discovered by William Harvey in 1668.
(a) Blood: It is a fluid tissue consisting of,
1. Plasma.
2. Corpuscles or cells.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

1. Plasma: It is a straw yellow (almost colourless) – homogenous matrix containing large amount of water V. (about 90%). A number of gases (O2, CO2) and substances are dissolved in it. Plasma also carries  metabolic wastes, hormones, antibodies, etc. Plasma is O,the matrix and blood corpuscles are suspended in it.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.1

2. Blood corpuscles: They are of 3 types, namely
(i) Erythrocytes or RBCs (Red Blood conpuscles).
(ii) Leucocytes or WBCs (White Blood conpuscles).
(iii) Platelets.
(i) Erythrocytes: They are circular in outline but look like biconcave from sideview. In mammals RBCs are enucleate upon maturation (except those of the family Camellidae). Cytoplasm includes haemoglobin, the iron pigment.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.2

Haemoglobin has greater affinity for O2. Thus RBCs transport O2 Surfilce view Surface view to various tissues. The number of RBCs is about 5 million per cubic mm of blood. They have a short life span of about 120 days.

(ii) Leucocytes: These are large, and colourless cells which are fewer in number. Their number varies from 5000 to 9000 per cubic mm of blood. They are of two types.
a. Granulocytes
b. Agranulocytes.

a. Granulocytes: They are large amoeboid cells with granular cytoplasm. The nucleus shows three to five lobes. They are of three types based on the staining property.
1. Eosinophils
2. Basophils
3. Neutrophills.

1. Eosinophils: They constitute 2 to 4 % of the  leucocytes, i.e ., their number ranges from 180 – 360/mm3 of blood. They are characterised by the presence of coarse cytoplasmic granules that stain deep red with acidic stain like Eosin. The nucleus is bilobed. They produce antihistamines that destroy antigen – antibody, and combat against irritants causing allergy.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.3

2. Basophils: They constitute only 0.5 – 1 % of the leucocytes i.e., their number range from 45 – 90/mm3 of blood. Basophils are structurally very much similar to eosinophils. However coarse cytoplasmic granules are few in number, and irregular in shape. They stain deep blue with basic stains like methylene blue. They contain heparin, histamine, and serotonin, and are believed to be involved in allergic reactions.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.4

3. Neutrophils: They constitute 60 – 70% of  the leucocytes i.e., their number range from 4.000 – 6.000/ mm3 of blood. They are characterised by the presence of fine cytoplasmic granules that stain pinkish with neutral stains. They possess nucleus with 2 -5 lobes. Neutrophils ingest pathogens, hence defensive in function.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.5

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

b. Agranulocytes: They are few in number. They are almost oval or spherical in shape with large kidney shaped nucleus. The cytoplasm is smooth or less granulated.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.6

They are of two types.
1. Lymphocytes (produced in lymph nodes).
2. Monocytes (produced in bone marrow).

1. Lymphocytes: They are produced in the lymph nodes (lymphoid tissue) and they constitute 20 – 25% of the leucocytes i.e. their number range from 1800 – 2250/mm3 of blood. They are characterised by relatively large round nucleus surrounded by a thin rim of cytoplasm. They produce antibodies concerned with immunity. Lymphocytes are of two types.

  • T lymphocytes: Concerned with cellular immunity.
  • B lymphocytes: Concerned with humoral immunity.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.7

 

2. Monocytes: They are produced in the bone marrow (myeloid tissue). They constitute 3 – 8% of the leucocytes i.e .. 270 – 720/mm3 of blood. They have large horse shoe shaped or kidney shaped nucleus. They are phagocytic, and hence destroy invading microorganisms.

Functions of leucocytes :
They defend the body either by ingesting pathogens which are harmful or by producing antibodies against foreign bodies.

(iii) Platelets: They are also called thrombocytes. They are small fragments of megakaryocytes with granular form of cytoplasm. Nucleus is absent. The number varies from 2 to 3 lakh per cubic mm of blood. Platelets are brittle, hence break up to release clotting proteins like prothrombin, and thromboplastin to bring about clotting.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.8

General functions of blood:
1. Blood transports food molecules and oxygen to various tissues.
2. Removes CO2 and the nitrogenous wastes from the tissues, and transports them to lungs and kidneys respectively.
3. Maintains constant temperature of the body.
4. Protects the body by producing antibodies and ingesting pathogens.
5. Also carries hormones and vitamins.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

In 1900 a German Physiologist, Karl Landsteiner classified human population into four types based on different blood groups which in turn is based on the presence of antigen on the membrane of RBC. These blood groups are:
1. Blood group – A.
2. Blood group – B.
3. Blood group – AB.
4. Blood group – O.

Antigens (Immunogens): An Antigen is a specific glycoprotein present in the RBC. Landsteiner discovered two types of antigens or isoagglutinogens called A and B on the surface of RBC of humans. These antigens are chemically muco-polysaccharides. He found that, out of A and B antigens, a person may contain either one or both or neither of them on the membrane of RBC. Type of antigen present on the membrane of RBC determines the blood group.

Antibodies (Immunoglobulins) : Antibody is a specific protein present in the serum of blood. These are also called isoagglutinins. There are 2 types of antibodies namely. Anti-a and anti-b. Antibodies act as a defense system against infections. Fortunately no antibodies are synthesized naturally against the antigens present in one’s own blood cell except in certain autoimmune disorders

Blood Group:

Blood Group on RBC Antigen present in RBC Antibody present in serum
‘A’ blood group
‘B’ blood group
‘AB’ blood group
‘O’ blood group
A
B
A & B
Absent
B
A
None
A & B

Blood Groups :
Person with ‘A’ blood group has ‘A’ antigen in his RBCs and ‘B’ antibody in his serum. Person with ‘B’ blood group has ‘B’ antigen in his RBCs and ‘A’ antibody in his serum. Person with ‘AB’ blood group has both ‘A’ & ‘B’ antigen in his RBCs and no antibody in his serum. Person with ‘O’ blood group has no antigen in his RBCs and both ‘a’ & ‘b’ antibody in his serum. From the above blood group chart, it is clear that antigen, and its incompatible antibody will never be in the same blood group.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

If it is the case, then the clumping of their own RBC can be seen. Antigen -A and antibody-a, cannot exist together in the same person. Likewise antigen-B, and antibody-b also cannot exist together. e.g. ‘A’ group person having antigen-A on the surface of RBC cannot have ‘A’ antibody in the serum of his own blood. Agglutination : When two different types of blood are mixed, clumping of RBCs occurs due to antigen-antibody reaction. Similar antigens, and similar antibodies act like lock, and key molecules, hence the clumping of blood. This is known as agglutination.

Rh Factor In Humans:
The surface of erythrocytes of some individuals contain one more type of antigen called Rh factor also called D antigen besides the A, and B antigens. It is named after the Macau, Rhesus monkey in which the Rh factor was first discovered. This was discovered by Landsteiner, and Weiner in 1940. This is an antigen present in the blood of 85% of human beings. Individuals having Rh antigen in their blood are known as Rh+ve. Individuals without Rh antigen in their blood are known as Rh-ve individuals.

The allele for Rh antigen is represented as ‘D’ The genotypes of Rh+ve persons can either be homozygous dominants (DD) or heterozygous (Dd). The Rh-ve persons are always homozygous recessive (dd). The Rh factor can be identified by using an antiserum-D.

Both Rh+ve, and Rh-ve persons are normal, and none has natural anti-Rh antibodies in their blood plasma. However, an Rh-ve person can develop these antibodies on receiving Rh antigens through transfusion of Rh+ve blood.

Haemolytic disease of newborn (HDN) or Erythroblastosis foetalis (Rh disorder): This disease is due to the incompatibility of Rh+ve, and Rh-ve blood which may result in the death of the child before or soon after birth. This problem arises when Rh-ve woman marries an Rh+ve man, and bears a Rh+ve foetus. Sometimes due to some placental defect some of the foetal RBC carrying Rh antigens may pass into mother blood stream, and cause the production of anti Rh antibodies.

The concentration of Anti-Rh antibodies is gradually built up in the mother, and she becomes sensitized for anti-Rh antibodies. There is no risk in the first pregnancy because enough antibodies are not found to destroy the foetus. In the second or subsequent pregnancies involving a Rh+ve child, these anti-Rh antibodies may return to the foetus through placenta and destroy the Rh antigen carrying RBC of foetus and is referred to as Haemolysis. This condition is called the haemolytic disease of new born (HDN), and the condition is identified as erythroblastosis foetalis. The disease tends to become worse in each subsequent pregnancy.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Symptoms:

  • Disease causes haemolytic anaemia often accompanied by jaundice, as liver capillaries become clogged with the remains of RBCs, and bile is being absorbed by the blood.
  • Increased bilirubin in blood greater than 18mg/d
  • Cerebral damages due to increased bilirubin content in the blood.
  • Enlargement of liver and spleen called hepatosplenomegaly.
  • Death of the foetus may occur before birth or soon after birth.
  • Effective prevention is achieved by treating such pregnant Rh-ve woman by injecting Rho- GAM injection.

Lymph:
It is a colourless mobile fluid or vascular connective tissue which flows in vessels called lymph vessels. Lymph is derived from intersitial or tissue fluid by means of fine, blind and iregular lymph capillaries. It is ultimeately drained into venous blood.

Functions
1. Large Molecules : Plasma proteins and other large macromolecules synthesised by liver and other parts of the body are picked up by lymph for passage to blood.

2. Hormones : Hormones are first passed into lymph before they are carried by blood.

3. Fat Drops : Fat is absorbed from alimentary canal by lymph capillaries called lacteals.

4. Waste Products : A part of the waste products and carbon dioxide are picked up from tissues by lymph to supplement their drainage by blood.

5. Lymphocytes : Lymphocytes are processed by lymph nodes and other lymphatic structures. The same are then passed by lymph into blood.

6. Excess Tissue Fluid : It picks up excess tissue fluid from interstitial ‘spaces.

7. Maintenance of Blood Volume : Lymph is responsible for maintaining blood volume which decreases due to seepage of plasma from blood capillaries into tissue fluid.

8. Pathogens : Pathogens and other foreign particles easily pass into lymph due to the higher permeability of lymph capillaries. They are taken to lymph nodes for destruction.

Circulatory pathway :
The circulatory patterns are of two types – open or closed. Open circulatory system is present in arthropods and molluscs, in which blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses. Annelids and chordates have the pattern where blood is always circulated through a closed network of blood vessels.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Structure of human heart: Heart is a muscular, cone shaped blood pumping organ, made up of cardiac muscles. It is dark red in colour, and resembles the shape of a closed fist. It weighs about 340 gm (in adults). Heart is situated obliquely a little towards the left side, between the lungs in the mediastinum. Heart is enclosed by a membrane called Pericardium.

The wall of the heart consists of three layers of membranes namely outer pericardium, the middle myocardium and the inner endocardium.

(a) Pericardium (Epicardium) : It consists of outer parietal and inner visceral pericardium membranes (Epicardium) with pericardial fluid is between them. It protects the heart from mechanical shocks and allows frictionless contraction.

(b) Myocardium : It is present below the pericardium, and consists of a specialized muscle tissue called cardiac muscle. It is involuntary in nature.

(c) Endocardium : It is the innermost layer of the heart wall, made up of thin connective tissue lined by squamous epithelial cells called endothelium.

Human heart is composed of four chambers. The upper two chambers are called right and left auricles and the lower two chambers are called right and left ventricles.

Auricles:
They are present in front of the ventricles. They are thin walled chambers separated from one another by interauricular septum or interatrial septum. The right auricle receives deoxygenated blood (impure blood) through superior, and inferior venacava.

The left auricle receives oxygenated blood from lungs through two pairs of pulmonary veins. The right and left auricles open into the right and left ventricle respectively through auriculo ventricular valves. In between the right auricle and right ventricle, there is a tricuspid valve [Guarded by three cusps].

In between the left auricle and left ventricle there is a bicuspid valve [mitral valve] which is guarded by two cusps. The cusps of these valves are attached to the papillary muscles of ventricles by a fibrous chordae tendinae.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Ventricles:
These are thick walled chambers. They are separated from one another by inter ventricular septum. The inner wall of both the ventricles possess muscular ridges called Trabaculae, and are made up of papillary muscles. From the right ventricle, pulmonary artery arises, which carries deoxygenated blood to the lungs for purification. From the left ventricle, the largest blood vessel called aorta arises which carries the oxygenated blood to different parts of the body through its branches.

The opening of the pulmonary artery into the right ventride is guarded by pulmonary semi lunar valve. The opening of the aorta into the left ventricle is guarded by an aortic semi lunar valve. Both the valves consist of three semi lunar cusps. These valves prevent the back flow of blood into the ventricles, and maintain unidirectional blood flow.

Mechanism of the working of heart :
The main function of heart is to maintain blood circulation in the body, by pumping blood. Pumping of the blood is accomplished by the contraction and relaxation of the heart chambers. The contraction state of the heart chambers is called systole and relaxation state is called diastole. A systole and a diastole together constitute one heart beat or cardiac cycle. Cardiac cycle is of three phases :

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Phase 1: Atrial Systole :
In this phase, the atria (auricle) contract to pump the blood into the ventricles.

Phase 2: Ventricular Systole :
In this phase, the ventricles contract to pump the blood into the aorta and pulmonary artery.

Phase 3: Complete cardiac diastole :
In this phase the deoxygenated blood flows into the right Auricle, and oxygenated blood into the left Auricle.

During atrial diastole, the right atrium is filled with deoxygenated blood received through the inferior and superior venacava. The left atrium gets filled with oxygenated blood through the pulmonary veins. During the atrial systole i.e, when the atria contract, the auriculo – ventricular valves kept open to allow the flow of blood into the respective ventricles. Thus the right ventricle receives de-oxygenated blood and left ventricle receives oxygenated blood.

During ventricular systole, i.e., when the ventricles contract, the auriculo-ventricular valves are kept closed, and the semi lunar valves are kept open to allow the flow of blood into the respective arteries. Thus, the de-oxygenated blood from the right ventricle flows through the pulmonary artery into the lungs for oxygenation / purification. Oxygenated blood from left ventricle flows into aorta for the distribution to various parts of the body.

Cardiac cycle (Heart Beat):
The sequential cyclic events of systole (contraction state) and diastole (relaxation state) together are known as one cardiac cycle or heart beat.

In a healthy person, the heart completes 72beats/min. On an average, each complete heart beat requires 0.8 sec in which systole of ventricles require 0.3 sec, systole of auricles require 0. 1 sec, diastole of the heart requires 0.4 sec.

Cardiac Output :
The amount of blood pumped by the right and left Ventricles per minute, is known as cardiac output. It is determined by multiplying the stroke volume With number of heart beats/min.
Cardiac Output = stroke volume x number of heart beats / minute
= 70 ml x 72 beats / min
= 5040 ml of blood.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Stroke volume:
The volume of blood pumped by the left ventricle per beat, is called stroke volume. In resting adults its average is about 70 ml.

Electrocardiogram:
The sequential spread of electric activity through the heart generates electrical currents that can be recorded from the surface of the body. The recording of electrical changes that occur during each heart beat is called electrocardiogram. The instrument used for recording the changes is called electrocardiograph.

Double circulation :
Human heart acts like a double pump.
The right side of the heart receives, and pumps deoxygenated blood and the left side of the heart receives and pumps oxygenated blood and hence both the routes are kept completely separate and there is no mixing of oxygenated and deoxygenated blood. This type of circulation is said to be complete double circulation. Double circulation involves shorter pulmonary circulation, and longer systematic circulation.

Pulmonary circulation :
During pulmonary circulation, the deoxygenated blood present in the right ventricle enters into the lungs during ventricular contraction through pulmonary artery. After the purification of blood in the lungs, the oxygenated blood enters into the left auricle of the heart through two pairs of pulmonary veins. This entire route constitutes the pulmonary circulation.

Systematic circulation :
During systemic circulation the oxygenated blood present in the left ventricle enters into aorta, and its branches supplying blood to different body parts. After exchanging O2 and CO, in the body parts, the blood becomes deoxygenated. The deoxygenated blood is brought back to right auricle of the heart through superior, and inferior venacava.

Origin and conduction of Heart beat :
In human beings the heart beat is initiated by a special group of muscles called Sino Atrial Node (SAN) present at the upper part of the right auricle. The SAN is also known as pacemaker of the heart because it initiates the electrical impulses for the heart beat.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

The SAN produces the electrical impulses which start a series of muscular contractions. The electrical impulses pass through the auricular muscles, and as a result hence auricles contract. Subsequently the impulses are passed on to the ventricles by the node (AVN). The bundle of HIS, divides into two branches-the right and left bundles.

The HIS bundle is further divided into Purkinje system of fibers in the walls of the ventricles. The of HIS bundle and its branches conduct the electrical impulses to ventricle muscles. Thus the of HIS bundle constitutes the conducting system. As a result of this, the ventricle contracts at the same time. This is known as ventricular systole. This results in the pumping of blood through h the aorta, and pulmonary artery.
1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation.9

 

Types of Heart:
Based on the nature of pacemaker there are two types of heart, namely.
1. Myogenic heart – In this type of heart a specialised muscular node namely Sino Atrial Node (SAN) present in the wall of the right atrium, is the pacemaker which generates electrical impulses. e.g. Myogenic heart is present in vertebrates and molluscans.

2. Neurogenic heart: In this type of heart a, group of nerve cells present on the dorsal surface of heart acts as pacemaker. It is called cardiac ganglion. e.g. in arthropods, neurogenic heart is present.

Mechanism of blood clotting (Best and Taylor’s theory) :
Blood has a unique property. As long as circulating inside the body it retains the fluid state however as soon as blood comes out of the body as a result of a cut or an injury, blood is transformed from fluid state to gel state, preventing further loss. This self regulating mechanism of the blood is known as clotting of the blood.

The mechanism of blood clotting is explained by various theories out of these ‘Best and Taylor’s theory is one. According to this theory, four factors are responsible for blood clotting.
1. Prothrombin : Produced by the liver and present in plasma.
2. Thromboplastin : An enzyme released from damaged tissues, present in the body tissues.
3. Calcium ions : Present in the plasma of the blood.
4. Fibrinogen : Produced by the liver and present in plasma.
Chemical events leading to the formation of blood clot as suggested by ‘Best and Taylor’s’ theory can be represented as follows.
\(\text { Prothrombin } \longrightarrow \text { Thrombin (Active) }\)
\(\text { Fibrinogen (soluble) \longrightarrow Thrombin } \rightarrow \text { fibrin (insoluble) }\)

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

The reaction shown above indicates that the inactive Prothrombin is converted into active thrombin by the catalytic activity of enzyme Thromboplastin in the presence of Ca2+. The activated thrombin reacts with soluble fibrinogen, resulting in the formation of insoluble fibrin. The fibrin threads forms a mesh like network in which the blood components get entangled, and results in blood clot and thus prevents bleeding.
Best and Taylor’s theory doesn’t consider the role of platelets in blood clotting mechanism.

Blood Pressure (BP) :
The force of the blood against the walls of the blood vessels creates a pressure known as blood pressure. The B.P. is maximum during the ventricular systole. It is called systolic B.P (SBP). The B.P. is minimum during ventricular diastole. It is called diastolic B.P (DBP). The B.P is measured by an instrument called sphygmomanometer invented by Stephen Hales. The systolic pressure in a normal person is 120 mm of Hg, and diastolic pressure is about 80 mm of Hg.

Therefore the normal BP can be written as
The difference between systolic and diastolic pressure is called pulse pressure. Its averages is about 40 mmofHg. [120-80=40mm of Hg], In normal human adults systolic pressure may go up to 150 mm of Hg, and diastolic BP may vary from 60-80 mm of Hg.

Regulation of heart activity:
Even though SAN initiates heart beat other factors like autonomic nervous system and hormones regulate the cardiac activity.

Cardioregulatory centre of the medulla through chemo receptors and baro receptors (sensor receptors) can also regulate cardiac activity.  The sympathetic nervous system travels from the cardio-regulatory centre down to spinal cord, SAN, AVN and myocardium to regulate the heart beat rate. Certain hormones like epinephrine, thyroxin and ions can affect heart functioning.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Disorders Of Circulatory System:
Hypertension or High BP : Whenever the Blood pressure values are above the normal values, the condition is termed as hypertension, and the BP is high Blood Pressure.
To be called hypertensive, a person he should register a systolic pressure greater than 150 mm of Hg and a diastolic pressure greater than 95 mm of Hg.
\(\text { High Blood pressure } \Rightarrow \frac{150 \mathrm{~mm} \text { of } \mathrm{Hg}}{95 \mathrm{~mm} \text { of } \mathrm{Hg}}\)

Causes :
1. Atherosclerosis : Narrowing of blood vessels due to accumulation of salt and cholesterol.
2. Arteriosclerosis : Hardening of arteries due to the loss of their elasticity.
3. Excessive intake of sodium salts.
4. Mental stress.
5. Consumption of alcohol and tobacco smoking.
6. Obesity. (Excessive body fat).

Effects on sympotms:
1. Headache, tiredness and giddiness.
2. Paralytic strokes.
3. Left ventricular failure.
4. Development of heart attack.

Preventive measures against HBP:
1. Good food habits with a low salt diet.
2. It can be prevented by practicing relaxation techniques like yoga meditation and physical exercises.
3. By avoiding tobacco smoking and consumption of alcohol.
4. Being free from mental stress.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Hypotension or low Blood Pressure :
Whenever the Blood Pressure values are less than the normal values then the condition is termed as hypotension and Blood Pressure is called Low Blood Pressure.
\(\text { Low blood Pressure } \Rightarrow \frac{60-80 \mathrm{mmof} \mathrm{Hg}}{55-45 \mathrm{mmof} \mathrm{Hg}}\)

Causes :
1. Endocrine disorders.
2. Steroids deficiency.
3. Severe loss of blood due to accidents and severe bums.
4. Excessive loss of body fluids due to vomiting or diarrhoea.

Effects :
1. Tiredness, giddiness, feeling cold and low metabolic activities.

Prevention of LBP:
1. It can be prevented by mild exercise and also by taking stimulants like coffee, tea and low dosages of alcohol.
2. Vasopressin drugs are commonly used to treat low BP.
Myocardial infarction (Heart attack or heart failure) :
Myocardial infarction is the local death of a small area or the tissue of the heart due to insufficient or non supply of blood and oxygen. It is also called Heart attack.

The arteries which are supplying the blood to the heart muscles are called coronary arteries.

Causes :
1. Arteriosclerosis : Narrowing of arteries due to the deposition of calcium salts and fibrous tissues in the inner wall of the artery.
2. Atherosclerosis : It is a disease of the arterial wall in which the inner layer becomes thick due to the cholesterol deposition in the form of plaques on the inner lining of the arteries. It is called coronary artery disease (CAD) or Ischemic heart disease (IHD).
3. Coronary thrombosis : The blockage of the coronary artery due to blood clot is called coronary thrombosis.
4. Embolus : Presence of debris, bubble of air, fat from broken bones in an artery is called embolus. It cuts-off circulation and results in heart attack.

Effects:
1. Angina pectoris : Severe and prolonged chest pain which radiates to the left shoulder and hand.
2. Profuse sweating.
3. Difficulty in breathing and shortening in breathing. .
4. Tiredness and giddiness.
5. Tightness in chest.
6. Anxiety.
7. Nausea, Vomiting and coughing.

Treatment:
1. Open heart surgery: Coronary angioplasty.
2. Bypass surgery.

1st PUC Biology Question Bank Chapter 18 Body Fluids and Circulation

Cyanosis :
Slightly bluish dark purple skin coloration, due to the deficiency of 02 in the systemic blood is called cyanosis.

It is a congenital heart disorder commonly found in newly born babies. A baby with bluish complexion especially on the tongue, lips and face due to insufficient oxygenated blood in the body is called a blue baby.

Causes :
1. Septal holes (ASD and VSD) ASD: Atrial septal defect VSD: Ventricular septal defect.
2. Congenital disposition of the pulmonary artery and aorta (Aorta arises from the right ventricle, and pulmonary artery from the left ventricle).
3. Valvular stenosis.
4. Incomplete, separation of heart chambers due to the formation of a weak septum.
5. Blue baby condition is also due to the tetralogy of fallot which is a combination of,
(a) An inter ventricular septal opening.
(b) An aorta arises from right ventricle.
(c) Pulmonary semi lunar valve-stenosis.
(d) Left ventricular hypertrophy.

Effects :
1. Appearance of bluish coloration.
2. Shortness in breathing.
3. Difficulty in sucking milk.
4. Reduced growth.
5. Heart failure.

1st PUC Biology Question Bank with Answers