18- BODY FLUIDS AND CIRCULATION

CHAPTER NO.18 BODY FLUIDS AND CIRCULATION

A178

INTRODUCTION:As we know, all living organisms are made up of cells .All living cells have to be provided with nutrients, Oxygen and other essential substances .Also the waste and harmful substances produced, have to be removed continuously for the

healthy functioning of tissues. Therefore, it is essential to have efficient

mechanisms for the movement of these substances to the cells and from the cells.

Blood is the most commonly used body fluid by most of the higher organisms including humans for this purpose.

Blood: Blood is a special connective tissue consisting of a fluid matrix called

plasma and formed elements.

PLASMA:It is Straw coloured, viscous fluid constituting nearly 55% of the blood.

90 -92 percent of plasma is water and protein contributes 6 - 8 percent of it.

Three types of protein are present in plasma:

1. EERE - Helps in blood clotting or coagulation.

2. TE - !nvoived in the defence mechanism of the body.

3. EY - Helps in maintaining osmotic balance.

Plasma also contains small amounts of minerals like Nat+,Ca++,Mb++, HCO3-,Cl-

etc.Factors for blood coagulation are also present in plasma in an inactive form.

Plasma without clotting factors is called Serum.

FORMED ELEMENTS:

There are three types of formed elements:

1. Red blood cells or Erythrocytes

2. White blood cells or Leukocytes

3. Platelets or Thrombocytes

1. ERYTHROCYTES or RBC are the most abundant of all the cells in blood

(5 - 5.5 per cubic mm).Itis formed in red bone marrow in adults.RBCs are devoid of nucleus and are biconcave in shape.

They have a red coloured ,iron containing complex proteins called haemoglobin which give it red colour.Haemoglobin plays a significant role in transport of respiratory gases.Life span of RBC is 120 days after which they are destroyed in spleen which is called the graveyard of RBC.

2. LEUCOCYTES or WBCs They are colorless due to absence of haemoglobin They are nucleated and are lesser in number(6000-8000 per cubic mm)Leukocytes are generally short lived Leukocytes are of 2 types

A. Granulocytes

B. Agranulocytes

A.GRANULOCYTES: These contain granules in the cytoplasm and are of

three types-

1. Eosinophils(2-3%) resist infection and are associated with allergic reaction

2. Basophils(0.5-1%) secrete histamine, serotonin and heparin.and are involved in inflammatory reaction

3. Neutrophils(60-65%) are phagocytic cells which destroy foreign organisms entering the body.

B. AGRANULOCYTES: They do not contain granules in the cytoplasm. These are of two types-

1. Monocytes(6-8%) are phagocytic cells which destroy foreign organisms

entering the body.

2. Lymphocytes (20-25%) are of 2 major types- B Lymphocytes and T Lymphocytes.Both B and T Lymphocytes are responsible for immune response of the body.

3. PLATELETS Also called Thrombocytes.

These are formed in the bone marrow from the cell fragments of megakaryocytes

Blood contains 1,50,000 -3,50,000 platelets per cubic mm Platelets help in coagulation or clotting of blood Reduction in their number leeds to clotting disorders which will lead to excessive loss of blood from the body.

LET US KNOW WHAT WE HAVE LEARNT!

1. Multiple Choice Questions:

|. Which one of the following types of cells lacks a nucleus?

(a)RBC

(b)Neutrophil

(c)Eosinophils

(d)Monocytes

ll. Cells involved in inflammatory reaction are:

(a)Basophil

(b)Neutrophil

(c)Eosinophils

(d)Lymphocytes

Ill. Mark , among the following a cell which exhibit phagocytic activity:

(a)Neutrophil

(b)Basophil

(c)Eosinophils

(d)RBCs

IV. Graveyard of RBCs is

(a)Liver

(b)spleen

(c)kidney

(d)Thymus

V. Which Leukocyte releases Heparin and Histamine in the blood

(a)Neutrophil

(b)Basophil

(c)Eosinophils

(d)Monocytes

2. True/False:

|. Life span of RBCs is 120 days.

Il. Leukocytes help in blood coagulation.

Ill. Monocytes and neutrophils are phagocytic cells.

3. Fill in the Blanks:

|. Plasmawithout__is called serum.

ll. ~~ and Monocytes are phagocytic cells.

lll. Eosinophils are associated with ————_—sreactions.

ANSWER KEY: PART A

1. Multiple choice questions:

Ans 1:(a)RBC.

RBC is a nucleated cell.

Ans 2:(a)Basophils

Basophils are involved in inflammatory reactions.

Ans 3:(a)Neutrophil

Neutrophils destroy the foreign organism entering the body.

Ans 4:(b)spleen

RBCs are destroyed in spleen.

Ans 5:(b)Basophil

Basophil releases Heparin and Histamine in blood.

2. True/False:

|. True

ll. False-Platelets help in blood coagulation

Ii. True

3. Fill in the Blanks:

|. clotting factors

li. Neutrophils

Ii. = Allergic

1. Why erythrocytes are called Red Blood Cells?

2. What is the importance of Plasma proteins?

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

1. Name the components of Formed Elements in the blood and mention one major function of each of them?

A179

INTRODUCTION:In the last assignment we studied blood and its components. As we know, the blood of human beings differs in certain aspects though it appears to be similar.Various types of blood grouping have been done. Two very important and common types of blood group systems are:

1. ABO Blood groups

2. Rh blood group system

ABO Blood groups: It is based on the presence or absence of two surface

antigens on the RBCs namely Similarly plasma of different individuals

contains two natural antibodies. The distribution of antigens and antibodies in four groups of blood are Blood group A has A antigen and antibody Blood group B has B-antigen and bantibody a Blood group AB has both A and B antigens but no antibody

Blood group O has no antigens but with both antibodies a & b During the blood transfusion, any blood cannot be used. The blood of a donor has to be carefully matched with the blood of the recipient before any blood transfusion to avoid severe problems. The donor's compatibility is shown in the following table.

UNIVERSAL DONOR: The person with O blood group is called Universal donor as

it has no antigen and can donate its blood to a person with any blood group.

UNIVERSAL RECIPIENT: The person with AB blood group is called Universal

recipient as it has no antibody in their plasma so can receive blood from any blood

group.

RH BLOOD GROUP SYSTEM: Rh factor is an antigen protein present on the surface of RBCs.It was first discovered on the plasma membrane of RBCs of Rhesus monkey, so is called Rh factor. Later it was found in about 94% of human beings and was called Rh positive (Rh+). The person with no Rh factor is called Rh negative (Rh-).

An Rh -ve person, if exposed to Rh +ve blood, will form specific antibodies against the Rh antigens .Therefore the Rh group should also be matched before

transfusions.A special case of Rh incompatibility has been observed between the Rh-ve blood of pregnant mother with Rh+ve blood of the fetus. Rh antigen of the foetus do not get exposed to the Rh-ve blood of the mother in the first pregnancy as the two bloods are well separated by placenta. However during the delivery of the first child, there is possibility of exposure of maternal blood to small amounts of Rh+ blood from the foetus. In such case mother starts preparing antibodies against Rh antigens in her blood. In her second pregnancy Rh antibodies from the mother

(Rh-ve) can leak into blood of the foetus (Rh +ve) and destroy the foetal RBCs.

This could be fatal to the foetus or could cause severe anemia and jaundice to the

baby. This condition is called erythroblastosis foetalis .This can be avoided by administering anti -Rh antibodies to the mother immediately after the delivery of the first child.

COAGULATION/CLOTTING OF BLOOD

DEFINITION: The property of blood to change from fluid to gel state when coming

in contact with air in response to an injury or trauma is called blood clotting.

AIM: To prevent excessive loss of blood from an injury, so is a natural defensive

mechanism.

MECHANISM: When there is an injury in the body, it stimulates the platelets in the

blood to release Thrombokinase or Prothrombinase which activate the

mechanism of coagulation. The injured tissue can also initiate blood coagulation by releasing Thromboplastin which gets converted into Thrombokinase /

Prothrombinase. In the presence of Calcium ion, Thrombokinase activates prothrombin and from Thrombin. Prothrombin is formed by the liver in the presence of vitamin K. Thus Calcium ion and vitamin K play important roles in blood clotting.

Thrombin acts on fibrinogen, present in plasma and converts it into fibrin. Fibrin

threads polymerize and forms a mesh work which traps blood cells, platelets etc. to

form a clot. So the process is called blood clotting.

LET US KNOW WHAT WE HAVE LEARNT!

PART A: VERY SHORT ANSWER TYPE QUESTIONS:

1. Multiple Choice Questions:

|. Vitamin which is essential for blood clotting is

(a)Vitamin A

(b)Vitamin B

(c)Vitamin C

(d)Vitamin K

ll. The most important mineral for blood coagulation is

(a)Calcium

(b)Magnesium

(c)Sodium

(d)lron

lil. | Which blood group is called Universal recipient

(a)Blood Group A

(b)Blood Group B

(c)Blood Group AB

(d)Blood Group O

IV. Which blood group is called a Universal donor?

(a) Blood Group A

(b) Blood Group B

(d) Blood Group O

V. Which of the following are involved in blood clotting at the injury?

(a) Platelets

(b) RBCs

(d) Monocytes

2. True/False:

|. Aperson with B blood group cannot donate blood to a person of A

blood group.

Il. | Blood group is designated on the basis of presence of antibodies in the

blood plasma.

Ill. Aperson with AB blood group is a universal recipient.

3. Fill in the Blanks

l. w.............40N plays an important role in the blood clotting.

ll. | Rh factor was first discovered on the plasma membrane of RBCs of....

lll. Aperson of O blood group has ........and .........antibodies in his blood plasma.

ANSWER KEY: PART-A

1. MULTIPLE CHOICE QUESTIONS:

Ans 1: (d)vitamin K.

Vitamin K is required for the formation of Prothrombin in the liver.

Ans 2: (a) Calcium

Calcium ion is required for the formation of thrombin from prothrombin

Ans 3: (c) Blood group AB

Blood group AB has no antibody in their plasma so can receive blood from any blood group.

Ans 4: (d) Blood group O

Blood group O has no antigen and can donate blood to any person.

Ans 5: (a) Platelets

At the site of injury Platelets release thrombokinase or Prothrombinase which activate the mechanism of coagulation.

2. TRUE/FALSE:

|. True

|. False-Blood group is designed on the basis of presence of antigens on

the surface of RBCs.

Ii. True

3. FILL IN THE BLANKS:

|. Calcium

ll. Rhesus Monkey

Il. Anti A and Anti B

PART B: SHORT ANSWER TYPE QUESTION:

1. What is Erythroblastosis foetalis?

2. Person with blood group O is called Universal donor. Why?

3. Thrombocytes are essential for coagulation of blood. Comment.

PART C: LONG ANSWER TYPE QUESTION:

1. Explain different types of blood groups and donor compatibility by making

a table.

A180

INTRODUCTION:It is a clear to pale white fluid derived from tissue fluid which

circulate throughout the lymphatic system.

The main function of lymph is to protect the body from harmful germs.Lymph is also called the middleman of the body.

COMPOSITION OF LYMPH

1. Lymph plasma

2. Lymph Corpuscles

3. Lymphoid Organs

LYMPH PLASMA It consists of less calcium, few blood proteins which includes albumin : globulin to be 1:5, fibrinogen content is low along with that of phosphorous.

Globulin proteins which are actual antibodies are found in lymph plasma.

LYMPH CORPUSCLES These are leucocytes (White Blood Cells) and amoeboid cells. Erythrocytes and blood platelets are absent.

LYMPHOID ORGANS Numerous lymph nodes are present deep inside the body.These lymph nodes are connected to lymphatic vessels which circulate the lymph throughout the body.The lymph gets filtered at the lymph nodes.The spleen, tonsils, adenoids and thymus are also the lymphoid organs.

The spleen is considered as the largest lymphatic organ in the system. An

elaborate network of vessels is called the Lymphatic System.Spleen maintains mature new lymphocytes and also synthesizes antibodies.Lymph and tissue fluid both have blood clotting property.

OTHER COMPONENTS OF LYMPH

1. Carbohydrates

2. Lymphocytes

3. Water

4. Urea

5. Chlorides

6. Enzymes

7. Very low amount of fat

8. Proteins

9. Non Protein Substances.

FUNCTIONS OF LYMPH Lymph performs many important functions. Few major functions of

lymph are mentioned below:

1. Itkeeps the body cells moist.

2. It transports oxygen, hormones and nutrients to different parts of the body.

3. Itremoves metabolic waste from the cells.

4. It transports antibodies and lymphocytes to the blood.

5. It prevents entry of microbes inside the lymph nodes.

LET US KNOW WHAT WE HAVE LEARNT!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

(A) MULTIPLE CHOICE TYPE QUESTIONS

1. What is the fluid that flows in the lymphatic system?

a) Blood

b) Lymph

c) Urine

d) None of the above

2. One of the main component of lymph is:

a) Red Blood Cells

b) Bile

c) White Blood Cells

d) None of the above

3. What kind of cells do lymph nodes produce?

a) Lymphocytes

b) Red Blood Cells

c) Nerve Cells

d) None of the above

4. Which of these is a part of the the lymphatic system?

a) Spleen

b) Thymus

c) Tonsils

d) All of these

5. Largest lymphatic organ is

a) Spleen

b) Thymus

c) Tonsils

d) None of these

(B) FILL. IN THE BLANKS:

(a)............... proteins which are actual antibodies are found inlymph

plasma.

(b)..............., tonsils and thymus are also the lymphoid organs.

(C )................. removes metabolic waste from the cells.

(C) TRUE /FALSE

(a) Lymph prevents entry of microbes inside the lymph nodes.

(b) Blood is the fluid that flows in the lymphatic system.

(c ) Lymph keeps the body cells moist.

ANSWER KEY: PART-A

(A) MULTIPLE CHOICE TYPE QUESTIONS :

1. (b) Lymph (Lymph is the fluid which flows in the Lymphatic

system).

2. (c) White Blood Cells (The main component of lymph is

White blood cells).

3. (a) Lymphocytes (Lymph Nodes produce lymphocytes).

4. (d) All of these (Spleen, Tonsils, thymus are the parts

of Lymphatic System).

5. (a) Spleen (Spleen is the largest Lymphatic Organ).

(B) FILL IN THE BLANKS:

(a) Globulin Proteins

(b) Spleen

(C) TRUE /FALSE

(a) True

(b) False (Lymph is fluid that flows in the lymphatic system).

(c ) True

PART: B SHORT ANSWER TYPE QUESTIONS:

1. Name the Lymphoid Organs.

2. Write the composition of Fluid.

3. Name the Lymph corpuscles.

PART: C - LONG ANSWER TYPE QUESTION:

1. What are the components and functions of Lymph?

A181

INTRODUCTION:HEART:The mesodermally derived organ is situated in the thoracic cavity, in between two lungs slightly tilted to the left. It has the size of clenched fist. It is protected by a double walled membranous bag pericardium enclosing the

pericardial fluid.

STRUCTURE OF HUMAN HEART:Our heart has four chambers, two relatively small upper chambers called atria and two larger lower chambers called ventricles.A thin muscular wall called the inter-atrial septum, separates the right and left atria whereas a thick walled inter ventricular septum, separates the left and the right ventricles.The atrium and the ventricles of the same side are also separated by a thick

fibrous tissue called the atrio- entricular septum.However, each of these septa is provided with an opening through which the two chambers of the same side are connected.

The opening between the right atrium and the right ventricle is guarded by a valve formed of three muscular flaps. The tricuspid valve, whereas bicuspid or mitral valve guards the opening between the left atrium and the left ventricle.

The opening of the right and left ventricles into the pulmonary artery and the aorta

is provided with semilunar valves.The valves in heart allow flow of blood in one direction.The entire heart is made up of cardiac muscles.A patch of tissues called sinoatrial node is present in right atrium.

Another mass called atrio ventricular node is present in left comer of right atrium.

A bundle of nodal fibres which passes through the atrio -ventricular septa to inter ventricular septum divides into right and left bundle are called PURKINJE FIBRES

or BUNDLE OF HIS. These can generate the maximum of action potentials. 70-75

min. and responsible for maintaining rhythmic contractile activity of heart.

LET US KNOW WHAT WE HAVE LEARNT!!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

a) MCQs:

1. How many chambers human heart has?

a) 1

b)2

c)3

d)4

2. The opening between the right atrium and right ventricle is guarded by

a) Tri cuspid valve

b) bicuspid valve

c) none of above

d) both

3. Where is sino atrial node situated?

a) Left auricle

b) right auricle

c) right ventricle

d) left ventricle

4. Our heart normally beats:

a) 70-75/ min

b) 80-85/min

c)100-120/min

d) none of the above

5. Where is purkinje fibres situated?

a) Auricles

b)ventricles

c)atrio ventricular septum

d) none of these

b) True/False:

1. Heart is protected by a single membrane.

2. Our heart has two chambers.

3. The valves in the heart allows the flow of blood in one direction

c) Eill ups:

1. Mass of the tissues is seen in the lower left corner of right atrium is

2. Our heart beats normally....... times in a minutue.

Answer key: Part—A

b) MCQs:

1. d Chambers in heart=4

2. a Tricuspid valve

3. b Right auricle

4. a 70-75/ min

5. c atrio ventricular septum

d) True/False:

1) False: Heart is protected by a double membrane.

2) False: Our heart has four chambers.

3) True

e) Fill ups:

1) atrio ventricular node

2) 70- 75/min

PART: B_ SHORT ANSWER TYPE QUESTIONS:

Q1. Sino-atrial is called the pacemaker of our heart ?

Q2. What are semilunar valves?

Q3. Where is Purkinje fibres situated?

Q4. How action potential is generated in heart

PART: C_ LONG ANSWER TYPE QUESTIONS:

Q1. Explain internal structure of human heart with well labelled diagram.

A182

INTRODUCTION:When multicellular organisms need a system to transport oxygen and

nutrients throughout the body, that system is known as the Circulatory system. In living organisms, the circulatory system has two pathways. These two circulatory pathways are:

Open type

Closed type

Open circulatory system:It is the one in which blood pumped by the heart passes through large vessels into open spaces or body cavities called Sinuses. Example:

arthropods and molluscs.

Open Circulatory System is the system that is primarily found in invertebrates. In open circulatory system, the blood is not confined within

blood vessels. The blood bathes the organs and tissues directly. Because of

this, the blood and the interstitial fluid have no distinction. Thus, the term

haemolymph is used. The haemolymph is pumped by the heart is pumped by

the heart through the vessels into the sinuses and then to the surrounding

cells where exchange of materials occur. The haemolymph is taken back to

the heart through ostia that close via the valves during the heart contraction.

The haemolymph is composed of fluid plasma (containing water, organic compounds, and inorganic salts such as Na*, Cl, Mg**, and Ca?*). There are also free floating cells called haemocytes that are involved in the immune function.

Closed circulatory system

In this, the blood pumped by the heart is always circulated through a closed

network of blood vessels. Example: Annelids and chordates. In closed Circulatory System, the presence of vessels conducts blood throughout the body. Blood flows inside the body through vessels such as arteries, veins and capillaries.

Closed type circulatory system is more advantageous as the flow of fluid can be more precisely regulated.

Human circulatory system

Human beings follow a closed circulatory system which means that the blood

is always enclosed in vessels and the heart while circulating throughout the

body. Travelling through arteries and veins, blood carries important

molecules throughout the body and is always confined.Advantage of Closed Circulatory System Compared to the open circulatory system, the closed circulatory system

operates with much higher blood pressure. It is said to be more efficient

considering that it uses much less blood for even faster and higher ievels of

distribution.

LET US KNOW WHAT WE HAVE LEARNT!!

PART: A VERY SHORT ANSWER TYPE QUESTIONS

1.Which of the following organism has an open circulatory system?

(a) Humans

(b) Birds

(d)Grasshoppers

2.What is the major differance between and open and closed circulatory system?

(a) Function

(b) Material transported

(d) Structure and design of vessels

3.An open circulatory system describes?

(a) A circulatory system that is open to the environment.

(b) A circulatory system in which blood and interstitial fluid are allowed

to mix.

(d) A circulatory system that has two loops: one for oxygenated blood,

one for waste products.

4.What is the purpose of the circulatory system?

(a) Digest food

(b) Transmit feelings

(d) Produce proteins

5.How many types of circulatory pathways are present?

(a) 1

(b) 2

(d) 4

(2)TRUE OR FALSE

1. In open type circulatory system, the blood is pumped out of the heart

and the cells and tissues are directly bathed in it.

2. Chordates have open type circulatory system.

3. Open type circulatory system is more efficient than closed type

circulatory system.

(3)FILL IN THE BLANKS

1. In open type circulatory system, since blood and interstitial fluids

have no distinction, term is used for that fluid.

2. Annelids and chordates have type of circulatory system.

ANSWER KEY:PART-A

(MCQ)

1. (d) Grasshoppers

2. (d) Structure and design of vessels

3. (b) A circulatory system in which blood and interstitial fluid are

allowed to mix.

4. (c) Transport blood and nutrients

5. (b) 2

(2)TRUE OR FALSE

1.True

2.False Chordates have closed type circulatory system.

3.False Open type circulatory system is less efficient than closed type

circulatory system. Closed circulatory system is said to be more efficient considering that it uses much less blood for even faster and higher levels of distribution.

(3)FILL IN THE BLANKS

1. Haemolymph

2. Closed

PART: B SHORT ANSWER TYPE QUESTIONS:

1. What do you mean by circulatory system?

2. Name the two types of circulatory pathways found in animals.

3. What is the Advantage of Closed Circulatory System?

PART: C LONG ANSWER TYPE QUESTIONS:

1. What is a circulatory pathway? Briefly describe the types of circulatory

pathways with the help of well labelled diagram.

2. Differentiate between open and closed type circulatory system ina

tabulated form.

A183

INTRODUCTION:Higher vertebrates such as amphibians, reptiles, birds and mammals have arterio-venous heart because both oxygenated (arterial) blood and

deoxygenated (venous) blood comes to it. Amphibians have three chambered heart- two auricles and one ventricle. Reptiles have

incompletely four chambered heart. In crocodiles (reptiles), birds and

mammals heart is four chambered — two auricles and two ventricles. During

single cardiac cycle, blood goes twice in the heart which is known as double circulation. In amphibians and reptiles (except crocodile) there is mixing of oxygenated and deoxygenated blood in ventricle. So, it is incomplete double circulation in these animals. Whereas perfect separation of arterial and venous blood in birds and mammals, have ensured complete double circulation. In double circulation, part of blood goes to lungs for oxygenation. The oxygenated blood comes back to heart for pumping into

rest of the body. The two types of circulation are called pulmonary

circulation and systemic circulation respectively.

1. PULMONARY CIRCULATION - it is circulation of blood between heart and lungs. In Pulmonary circulation pathway, the deoxygenated blood is pumped out from the right atrium into the right ventricle as the tricuspid valve opens. This blood is then carried away from the heart by pulmonary arteries to the lungs. In the lungs, the gaseous exchange occurs (as CO2is released and O2 is picked up) and deoxygenated blood is purified and

oxygenated. After that, the pulmonary veins bring back the oxygenated blood to the left atrium of the heart. This blood then enters the left ventricle from where it can be circulated throughout the body parts.

2. SYSTEMIC CIRCULATION: Here the blood circulates between heart and all parts of the body except lungs. In systemic circulation, the heart supplies oxygenated blood from left atrium to the left ventricle via bicuspid valve. From left ventricle, blood enters aorta. From there, the blood travels through large arteries finish up in the capillary network. In the

process, the blood supplies necessary oxygen and other nutrients to tissues and collects the residual substances and carbon dioxide from there and returns deoxygenated blood into the right atrium and ventricle of the heart. Both pathways of blood circulation work together. Since blood has to reach every tissue and cell, the blood pressure in systemic circulation is

more than pulmonary circulation. ine separation of oxygenated and deoxygenated blood in double circulation allows for an efficient supply of oxygen to the body cells and delivers a greater blood flow rate.

PORTAL SYSTEM Normally veins after collection of blood carry it to the heart. The vein which after collection of blood carries and distributes it to another organ instead of heart is called portal system. Thus, portal veins act both as collecting and distributing vessels.

HEPATIC PORTAL SYSTEM:A unique vascular connection exists between the digestive tract and liver called hepatic portal system. Hepatic portal veins carries blood from intestine to the liver before it is delivered to the systemic circulation. It helps in transport and assimilation of digested food in liver.A special coronary system of blood vessels is present in our body exclusively for the circulation of blood to and from the cardiac muscles.

LET US KNOW WHAT WE HAVE LEARNT!!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

1. Which of the following statements is incorrect about double circulation?

(a) It occurs only in mammals.

(b) It occurs in all vertebrates.

(d) It is composed of pulmonary circulation.

2. How many chambers are present in the heart of crocodiles?

(a) Two

(b) Three

(d) Five

3. Which of the following organisms show incomplete double circulation?

(a) Birds

(b) Reptiles

(d) Crocodiles

4. Systemic circulation in the cardiac system refers to:

(a) Carry oxygenated blood

(b) Carry blood to the left side of the heart.

(d) Carry oxygenated blood from the lungs to the heart.

5. Oxygenated blood in the cardiac system:

(a) Leaves from the right side of the heart

(b) Leaves from the left side of the heart

(d) Does not leave the lungs

6. The hepatic portal vein drains blood to the liver from .

(a) Heart

(b) Kidneys

(d) Stomach

7. What is the hepatic portal system?

a) The connection between the digestive tract and kidneys.

b) The connection between the alimentary canal and heart

c) The connection between the alimentary canal and the brain

d) The connection between the alimentary canal and the liver as:

1. Double circulation checks the mixing of oxygenated and deoxygenated blood.

2. Human heart is three chambered.

3. Pulmonary artery carries deoxygenated blood.

4. In systemic circulation, blood circulates between heart and body

tissues.

5. In reptiles, heart is partially four chambered.

1. In pulmonary circulation, oxygenated blood is carried from to .

2. In systemic circulation, brings deoxygenated blood from all parts of body into the heart.

3. Amphibians and fishes show double circulation.

ANSWER KEY: PART -A

(1) Multiple choice questions

1. (b) It occurs in all vertebrates.

Explanation: Double circulation does not occur in fishes, amphibians and reptiles. It occurs only in crocodiles (Reptile), birds and mammals. So,double circulation does not occur in all vertebrates

2. (c) Four

3. (b) Reptiles

4. (c) Carry blood to the right side of the heart.

5. (b) leaves from the left side of the heart

6. (c) Intestine

7. (d) Hepatic portal system is connection between the alimentary canal and the liver.

(2) True or false

1. True

2. False. Human heart is four chambered - Two auricles and two ventricles.

3. True

4. True

5. True

(3) Fill in the blanks

1. Lungs, Heart

2. Vena cava

3. Incomplete

PART:B SHORT ANSWER TYPE QUESTIONS:

1. What is double circulation?

2. What is significance of double circulation?

3. What prevents mixing of arterial and venous blood in higher vertebrates?

4. What is function of hepatic portal system?

5. Which blood vessels supplies oxygen and nutrients to heart?

PART: C LONG ANSWER TYPE QUESTIONS:

1. What is double circulation? Explain the pulmonary and systemic circulation with the help of well labelled diagram.

2. How is blood circulation in amphibians and reptiles different from that of birds and mammals?

A184

INTRODUCTION:Regulation of cardiac activity:The heart is myogenic i.e. it is auto regulated by specialised muscles (nodaltissue). Nodal tissue has ability to generate action potentials without external

stimuli.So, when the cardiac muscles are stimulated these initiate the waves of

depolarization, called cardiac impulses, which are conducted along the

special cardiac muscles on the wall of the heart chambers.Initiation of heart beat is under three SPECIAL BUNDLES OF CARDIAC

MUSCLES called nodal tissues.

1. Sinu-auricular Node or Sinu-atrial node (S.A. Node): It lies in the right

upper corner of the right atrium. It is also called pacemaker as it is the first to

originate the cardiac impulses and determines the rate of heart beat. The

S.A. node can generate the maximum number of action potentials i.e. 70-75

per min and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Therefore, it is called the pacemaker. Our heart normally beats 70-75 times in a minute (average 72 beats per minute).

2. Atrio-ventricular node (A.V. Node): Itis also called pace setter. It lies

in the lower left corner of right atrium near the junction of interauricular and

interventricular septum. It is stimulated by the waves of contraction initiated

by S.A. node. It generates the cardiac impulses, which are conducted to the

muscles of ventricles throuah bundle of His and Purkinie fibres.

3. AV Bundle: It arises from A.V. node, descends in the inter-ventricular

septum and divides into two branches. These branches give rise to minute fibres throughout the ventricular musculature of the respective sides and are called Purkinje fibres. These fibres along with right and left bundles are known as Bundle of His.S.A. node, A.V. node, A.V. bundle and Purkinje fibres collectively form the

conducting system of the heart and is responsible for autorhythmicity of

heart. The conducting system of muscles has the ability to generate action potentials without any external stimuli i.e. it is autoexcitable. Hence, heart is called myogenic.Although heart beat in man is myogenic, but the rate of heart beat is both under nervous and endocrine controls.

(a) Nervous Control: Cardiac centre for the control of rate of heart beat lies

in the Medulla oblongata of brain. Cardiac centre can moderate cardiac function through Autonomous Nervous System (A.N.S).

Sympathetic and parasympathetic nerves from cardiac centre (part of A.N.S) innervate the S.A node or pacemaker of the heart. Action of these nerves is antagonistic to one another.Parasympathetic nerves tend to slow the rate at which impulse are

produced by SA node, thereby decreasing the rate and force of the heartbeat. Sympathetic nerves tend to speed up the rate of impulse production in SA node, thus, increasing the rate and force of the heart beat.Heart beat usually decreases during rest and increases during exercise and excitement, etc.

(b) Endocrine Control: Hormones adrenaline (epinephrine) and nor-adrenaline (nor-epinephrine) of adrenal medulla controls the rate of heart beat.Nor-adrenaline controls the rate of heart beat under normal conditions and Adrenaline accelerates the heart beat at the time of emergency.These hormones directly influence the S.A. node.

LET US KNOW WHAT WE HAVE LEARNT?

PART: A VERY SHORT ANSWER TYPE QUESTIONS

1. Which of the following regulates the normal activities of the heart?

(a) CNS

(b) Kidneys

(d) Eyes

2. Approximately, our heart beats times per minute.

(a) sixty four

(b) seventy two

(d) eighty three

3. Pick the incorrect statement about autonomic nervous system (ANS)

(a) ANS consist of two nerves

(b) Both ANS nerves contradict each other.

(d) Parasympathetic stimulation increases the contraction of auricles and ventricles

4. Role of pace-maker is:

(a) To increase heart beat

(b) To decrease the heart beat

(d) To control the blood supply to heart

5. Heart in humans is:

(a) Neurogenic

(b) Myogenic

(d) None of these

1. Normal activities of the human heart are regulated intrinsically, hence

it is neurogenic.

2. A special neural centre in the medulla oblongata can moderate the

cardiac function through CNS.

3. Parasympathetic neural signals increase the rate of heartbeat.

4. Adrenal medullary hormones can increase cardiac output.

1. Action of sympathetic and parasympathetic nerves is to one

another.

2. S.A. node lies in the right upper corner ofthe __—__atrium.

3... ~~——sAhhormone accelerates the heart beat at the time of emergency.

ANSWER KEY PART-A

(1) MCQs:

1. (c) Heart

Explanation: All the activities of the heart are regulated by specialised muscles

or the nodal tissue which is present in the upper corner of right atrium. This type

of heart which is auto-regulated by itself is known as myogenic heart.

2. (b) seventy two.

3. (d) Parasympathetic stimulation increases the contraction of auricles and

ventricles

4. (c) To initiates the heart beat

5. (b) Myogenic

(2) TRUE / FALSE:

1. False: Human heart is myogenic i.e. heart beat is initiated by heart itself.

2. False: Medulla oblongata can moderate the cardiac function through

A.N.S.

3. False: Parasympathetic neural signals increase the rate of heartbeat.

4. True: Adrenaline hormone increases the cardiac activity during emergency conditions while nor-adrenaline increases heart beat under normal conditions. Both ways, the rate of heart beats is increased, so is the strength of ventricular contraction and thereby the cardiac output.

(3) FILL IN THE BLANKS:

1. Antagonistic

2. Right

3. Adrenaline

PART: B SHORT ANSWER TYPE QUESTIONS:

1. What is the significance of atrio-ventricular node and bundle of His in

the functioning of heart?

2. Why S.A. node is called pacemaker of heart?

3. How is cardiac impulse conducted from right atrium to ventricular

muscles?

4. What is role of hormones in controlling the rate of heart beat?

5. Cardiac centre for control of heart beat lies where?

PART: C LONG ANSWER TYPE QUESTIONS:

1. Describe the intrinsic conducting system of heart responsible for

autorhythmicity of heart with the help of well labelled diagram.

2. Explain the cardiac centre for the control of rate of heart beat? How it

increases or decreases the rate of heart beat?

A185

INTRODUCTION:What is circulatory system?

The circulatory system may be defined as, the system which is involved in the

circulation of lymph and blood throughout the body. The circulatory system

consists of many parts like heart, blood vessels, blood cells, lymph, lymphatic

vessels, and glands.What is disorder?

A disorder is defined as a state of irregular functioning of the body.

DISORDERS OF CIRCULATORY SYSTEM MAY BE AFFECTED BY THE FOLLOWING FACTORS:

An emotional response to distressing events like an accident. Blockage of a blood vessel. Formation of tumours in blood vessels. Reduction in the artery diameter.

What is Disorder of Circulatory System?

The disorders of the circulatory system could be defined as any ailment which

affects the heart, blood vessels, and the blood cells. This disorder leads to the

insufficient or reduced transportation of blood, oxygen, hormones, and nutrients to

the tissue and cells.

TYPES OF DISORDERS OF CIRCULATORY SYSTEM:

HIGH BLOOD PRESSURE:The pressure which is created by the blood flow on the wall of blood vessels. In humans, the normal range of blood pressure is 120/80. In this range, 120 is the systolic blood pressure and 80 is the diastolic blood pressure.

Systolic blood pressure — It is defined as the pressure that is created in the arteries when blood flows through arteries to the rest of the body when the heartbeats.Diastolic blood pressure- It is defined as the pressure created in the arteries when the heart relaxes between the beats.If the normal blood pressure is higher than 140 over 90 or higher, it leads to hypertension. It has no signs and symptoms.High blood pressure could be caused by the following factors:

Intake of salty foods.Intake of too much alcohol.Intake of large amounts of fat-rich foods.

HIGH BLOOD PRESSURE (HYPERTENSION):

HYPERTENSION:If the normal blood pressure is higher than 140 / 90, it leads to hypertension. It has no signs and symptoms.

Hypertension may lead to heart diseases and improper functioning of some organs

like brain and kidney.Hypertension is the term for blood pressure that is higher than normal (120/80).In this measurement 120 mm Hg (millimetres of mercury pressure) is the systolic or pumping pressure and 80 mm Hg is the diastolic or resting pressure.

If repeated checks of blood pressure of an individual is 140/90 (140 over 90) or

higher, it shows hypertension.

SIDE EFFECTS OF (HYPERTENSION):High blood pressure leads to heart diseases and also affects vital organs like brain and kidney.

Coronary Artery Disease (CAD): Coronary Artery Disease, often referred to as

atherosclerosis, affects the vessels that supply blood to the heart muscle. It is

caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.

ANGINA PECTORIS:Angina is the condition in which chest pain occurs if the heart receives insufficient oxygen and nutrients through the blood vessels. Angina could be

caused by the different Coronary artery disease is also termed as atherosclerosis.

CORONARY ARTERY DISEASE is the disease which is caused by the deposition of waxy substances in the blood vessels which supplies the blood to the heart muscle and this deposition leads to the blockage of the blood flow. The examples of waxy substances are fat, cholesterol! and fibrous tissues. As a result, it may also cause a heart attack.Coronary Artery Disease (CAD) could be caused by the following factors:

1. Smoking.

2. High blood pressure.

3. High cholesterol.

4. Diabetes or insulin resistance.

ANGINA:It is also called ‘angina pectoris’. A symptom of acute chest pain appears when no enough oxygen is reaching the heart muscle. Angina can occur in men and women

of any age but it is more common among the middle-aged and elderly. It occurs due

to conditions that affect the blood flow.

HEART FAILURE:Heart failure means the state of heart when it is not pumping blood effectively enough to meet the needs of the body. It is sometimes cailed congestive heart failure because congestion of the lungs is one of the main symptoms of this

disease. Heart failure is not the same as cardiac arrest (when the heart stops

beating) or a heart attack (when the heart muscle is suddenly damaged by an

inadequate blood supply).

“LET US KNOW WHAT WE HAVE LEARNT!!”

PART-A VERY SHORT ANSWER TYPE QUESTIONS:

(a) MULTIPLE CHOICE TYPE QUESTIONS:

Q1. An adult human has systolic and diastolic pressures as:

(a) 80 mm Hg and 120 mm Hg

(b) 120 mm Hg and 80 mm Hg

(d) 80mm Hg and 80 mm Hg

Q2. Heart failure occurs due to

(a) heart stops beating

(b) damage of heart muscles

(d) all of the above

Q3. What is the full form of CAD?

(a) Canal artery disease

(b) Corona anal disease

(d) None of these

Q4. Heart failure may be caused by which of the following risk factor:

(a)Smoking

(b) Obesity

(d) All of the above

Q5. Symptoms of Angina-

(a) Fever

(b) Chest Pain

(c)Headache

(d) Vomiting

(b)True /False :

1. Angina occurs due to conditions that affect the blood flow.

2. If the normal blood pressure is lower than 120/ 80, it leads to hypertension.

3. Heart failure means the state of heart when it is not pumping blood

effectively enough to meet the needs of the body.

(c)Fillin the blanks:

Q1. is the term for blood pressure that is higher than normal

(120/80).

Q2. Coronary Artery Disease, often referred to as

ANSWER KEY: PART-A

(a)MULTIPLE CHOICE QUESTIONS:

1. (b) 120 mm Hg and 80 mm Hg

2. (c) Congestion of lungs

3. (c) Coronary artery disease

4. (d) All of the above

5. (b) Chest Pain

(b)TRUE/ FALSE:

1. True

2. False: If the normal blood pressure is more than 140/ 90, it leads to

hypertension.

3. True

(c)FILL IN THE BLANKS;

1. Hypertension

2. Atherosclerosis

PART(B) Short Answer Type Questions:

Q1.What is the consequences of Hypertension?

Q2. What is the difference between pumping & resting pressure?

Q3.What is the symptoms of ‘angina pectoris’?

PART (C) Long Answer Type Questions:

Q1. What is heart failure? How it is different from cardiac arrest?

A186

INTRODUCTION:Dear Students, as we have completed the chapter number XVIIl- Body

Fluids and Circulations. Now we will discuss about the differences or

comparison type questions. Some of the important differences in this

chapter - Body Fluids and Circulations described as given below:

Open and closed system of circulation

Blood and Lymph Arteries and Veins

Sinuauricular (S.A.) Node and Auriculoventricular (A.V.) Node

Systole and Diastole Lub (First heart sound) and Dup(Second heart sound)

P-wave and T-wave

A187

INTRODUCTION:Blood is most commonly used body fluid by most of the higher animals

including humans for transport of various metabolic substances and exchange of gases. Blood is a special connective tissue consisting of fluid matrix, plasma and formed elements. Erythrocytes, leucocytes and platelets are collectively called formed elements and constitute nearly 45 percent of the blood.Dear students, you have studied the whole chapter in the previous daily dose assignments. Now in this assignment we will go through all the diagrams that come across in this chapter.

As the blood passes through the cappillaries in tissues, some water along

with many water soluble substances move out into the spaces between the

cells. This fluid is called interstitial fluid or tissue fluid. An elaborate system

called lymphatic system collects this fluid and drains it back to the major veins. The fluid present in the lymphatic system is called lymph. Lymph is colourless fluid containing specialised lymphocytes which is responsible for immune responses of the body.

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 closed circulatory system in which the blood pumped by the heart is always circulated through a closed network of blood vessels.

Heart, the mesodermally derived organ,is situated in the thoracic cavity, in between the two lungs, slightly tilted to the left. Our heart has four chambers- two relatively small upper chambers called atria and two larger lower chambers called ventricles. SA node, AV node ,Bundle of his Purkinje fibres help in conductance of impulse which is myogenic ie originated by heart itself.

The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole.

Electro Cardio Gram(ECG) : Graphical representation of the electrical activity

of the heart during a cardiac cycle

LET US KNOW WHAT WE HAVE LEARNT!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

1. Vitamin which is essential for blood clotting is:

(a) Vitamin A

(b) Vitamin B

(d) Vitamin K

2. Approximately, how many times our heart beats per minute?

(a) sixty four

(b) seventy two

(d) eighty three

3. Which blood group is called a Universal donor?

(a) Blood group A

(b) Blood group B

(d) Blood group O

4. One of the main components of lymph is:

(a) Red blood cells

(b) Bile

(d) None of the above

5. Heart in humans is:

(a) Neurogenic

(b) Myogenic

(d) None of these

1. Our heart has two chambers.

2. The valves in the heart allow flow of blood in one direction.

3. Double circulation checks the mixing of oxygenated and deoxyadenated blood.

4. Normal activities of the human heart are regulated intrinsically, hence it is neurogenic.

1. ion plays an important role in blood clotting.

2. S.A. node lies in the right upper corner of the atrium.

3. Annelids and chordates have __ type of circulatory system.

ANSWER KEYPART: A

1. (d) Vitamin K

2. (b) seventy two

3. (d) Blood group O

4. (c) White blood cells

5. (b) Myogenic

1. False: Our heart has four chambers- two auricles and two ventricles.

2. True

3. True

4. False: Human heart is myogenic i.e. heart beat is initiated by heart

itself.

1. Calcium

2. Right

3. Closed

PART: B SHORT ANSWER TYPE QUESTIONS:

1. What do you mean by circulatory system?

2. Define lymphatic system?

3. What is ECG?

4. What is open and closed type circulatory system?

5. What prevents mixing of arterious and venous blood in higher animals?

PART: C LONG ANSWER TYPE QUESTIONS:

1. What is blood? Draw a flow chart to show various components of blood.

2. Explain internal structure of human heart with well labelled diagram.

3. What is double circulation? Explain the pulmonary and systemic circulation with the help of well labelled diagram.

4. What is a circulatory pathway? Briefly describe the types of circulatory pathways with the help of well labelled diagram.

5. Describe the intrinsic conducting system of heart responsible for autorhythmicity of heart with the help of well labelled diagram.

A188

RECAPITULATION:Dear students, in this Chapter of “Body Fluids and Circulation” we learnt that;Vertebrates circulate blood, a fluid connective tissue, in their body, to

transport essential substances to the cells and to carry waste substances from there.

Another fluid, lymph (tissue fluid) is also used for the transport of certain

substances.Blood comprises of a fluid matrix, plasma and formed elements. Red

blood cells (RBCs; erythrocytes), white blood cells (WBCs, leucocytes) and

platelets (thrombocytes) constitute the formed elements.All vertebrates and a few invertebrates have a closed circulatory system.Our circulatory system consists of a muscular pumping organ, heart, a

network of vessels and a fluid, blood.

Heart has two atria and two ventricles.

Cardiac musculature is auto-excitable.

Sino-atrial node (SAN) generates the maximum number of action potentials

per minute (70-75/min) and therefore, It sets the paceof the activities of the

heart. Hence it is called the Pacemaker.

About 70 ml. ofblood is pumped out by each ventricle during a cardiac cycle

and it is called the stroke or beat volume.

The Volume of blood pumped out by each ventricle of heart per minute is

called the cardiac output and it is equal to the product of stroke volume and

heart rate (approx 5 litres).The electrical activity of the heart can be recorded from the body surface by using Electro Cardio Graph and the recording is called Electro cardio gram (ECG) which is of clinical importance.

N.C.E.R.T. QUESTIONS WITH SOLUTIONS

Q. 1. Name the components of the formed elements in the blood and mention

one major function of each of them.

Ans. The formed elements of the blood are erythrocytes, leucocytes and platelets

and they constitute nearly 45% of the blood.Major Functions:

(i) Erythrocyles: The erythrocytes or red blood cells play a significant role in

transport of respiratory gases (O2 and CO,).

(ii) Leucocytes: The leucocytes or white blood cells play an important role to

fight against infections.

(iii) Platelets: Platelets or thrombocytes, are invoive in the coagulation or

clotting of blood. A reduction in their number can lead to clotting disorders,

which will lead to excessive loss of blood from the body

Q. 2. What is the importance of plasma proteins?

Ans. (i) Albumins maintain the osmotic pressure of blood

(ii) Globulins act as antibodies and provide immunity.

(iii) Fibrinogen and Prothrombin help in blood clotting at the injury.

(iv) Properdin kills many types of bacteria and inactivates viruses.

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

Ans. Blood is a mobile connective tissue derived from mesoderm which consists of

fiber free fluid matrix, plasma and other cells. It regularly circulates in the body, & takes part in transport of materials.

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

Ans. Double Circulation: In double circulation blood passes twice through the

heart during one complete cycle; Double circulation is carried out by two ways:

(i) | Pulmonary circulation

(ii) Systemic Circulation

SIGNIFICANCE OF DOUBLE CIRCULATION:

1. Ithelps in maintaining higher blood pressure.

2. — It allows a greater flow of blood to the tissues.

3. It helps in creating more pressure to pump blood around the whole body

tissues and organs.

4. Aseparation of oxygenated and deoxygenated blood is possible that leads to taking in oxygen-rich blood and removal of carbon dioxide from the blood

through the lungs.

5. Ithelps in producing a large amount of energy to maintain life processes

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

Ans.The heart among the vertebrates shows different patterns of evolution. Different

groups of animals have evolved different methods for blood transport. All

vertebrates possess a muscular chambered heart.

(1) Fishes have a 2-chambered heart with an atrium and a ventricle.

(2) Amphibians and the reptiles (except crocodiles) have a 3-chambered heart

with two atria and a single ventricle.

(3) In crocodiles, birds and mammals possess a 4-chambered heart with two atria

and two ventricles.

(4) In fishes the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned

to the Heart.

(5) In amphibians and reptiles, the left atrium receives oxygenated blood from the

gills/lungs/skin and the right atrium gets the deoxygenated blood from other

body parts. However, they get mixed up in the single ventricle which pumps out

mixed blood.

(6) In birds and mammals oxygenated and deoxygenated blood received by the

left and right atria respectively passes on to the ventricles of the same sides.

The ventricles pump it out without any mixing up, i.e. two separate circulatory

pathways are present in these organism. Hence, these animals have double

circulation.

Q. 9. Why do we call our heart myogenic?

Ans. Because in man, the nodal tissues of the heart (eg. S.A. node, A.V. node,

Bundle of His and Purkinje fibers) which collectively form the conducting system of

the heart and regulate the heartbeat, are groups of special cardiac muscle fibers.

Q10 Sino-atrial node is called the pacemaker of our heart, why?

Ans. Sino-atrial node of heart is responsible for initiating and maintaining its rhythmic activity, and determines the rate of heartbeat therefore it is known as

pacemaker of the heart.

Q11. What is the significance of atrio-ventricular node and atrio-ventricular

bundle in the functioning of heart?

Ans. Atrioventricular Node (AVN): It is the mass of tissue present in the lower left

corner of the right atrium close to the atrio-ventricular septum. It is stimulated by theimpulses that sweep over the atrial myocardium. It is too capable of initiating

impulses that cause contraction but at slower rate than SA node.Atrioventricular bundle (AV bundle): It is a bundle of nodal fibers, which continues from AVN and passes through the atrio-ventricular septa to emerge on the top of inter-ventricular septum. The AV Bundle, bundle branches and Purkinje fibers convey impulses of contraction from the AV node to the apex of the myocardium. Here the wave of ventricular action begins, than sweeps upwards and outwards, pumping blood into the pulmonary artery and the aorta.

This nodal musculature has the ability to generate action potentials without any

external stimuli.

Q. 12 Define a cardiac cycle and the cardiac output.

Ans. (i) Cardiac cycle the sequential event in the heart which is cyclically repeated

is called the cardiac cycle. It consists of systole and diastole of both the

atria and ventricles. It is completed in 0.8 seconds.

(ii) Cardiac Output is the volume of blood ejected from the ventricles of heart

in one minute. It is 5 liters per minute.

Q.13. Explain heart sounds.

Ans . During a cardiac cycle, two heart sounds can be heard:

1. Lub or Systolic sound or First heart sound: It is heard during the

begining of ventricular systole and is due to rapid closing of atrioventricular

valves.

2. Dubb or Diastolic sound or Second heart sound: It is heard during the beginning of ventricular diastole and is due to rapid closing of semilunarvalves.The heart sounds can be heard by an instrument called stethoscope by placing its receiver on left side of the chest.

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

Ans. Electrocardiograph (ECG): ECG is a graphical representation of the

electrical activity of the heart during a cardiac cycle. A patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity. For a detailed evaluation of the heart's function, multiple leads are attached to the chest region.Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.

The P-wave represents the electrical excitation (or depolarization) of the atria,which leads to the contraction of both the atria.The QRS complex represents the depolarization of the ventricles, which initiates the ventricular contraction. The contraction starts shortly after Q and marks the beginning of the systole.

The T-wave represents the return of the ventricles from excited to normal state

(repolarization).The end of the T-wave marks the end of systole.Obviously, by counting the number of QRS complexes that occur in a given time period, one candetermine the heart beat rate of an individual. Since the ECGs obtained fromdifferent individuals have roughly the same shape for a given lead

configuration,any deviation from this shape indicates at possible abnormality or

disease. Hence, it is of a great clinical significance.

A189

INTRODUCTION:Electro Cardio Graphy:

Electrocardiography is the non-invasive technique of measurement and recording

of electrophysiological activity of heart muscles using the electrodes placed on the

skin at different points such as wrists ankle and various regions on the chest.

A graphic record of the electrical activity of the heart is called Electro Cardio Gram

(ECG) or EKG. These variations are due to the development of electrical negativity

of excited muscles.An instrument used to observe the working of the heart is called

ELECTROCARDIOGRAPH. Electrocardiograph was discovered by Einthoven (1903), commonly called "Father of Electrocardiography", while ECG was first recorded by Waller. Most modern clinical electrocardiograph used is PEN RECORDER. It may be connected to an OSCILLOSCOPE which displays it on a

TV-type screen.ECG taken when patient is lying down is called Resting ECG while ECG taken when patient is exercising is called Stress ECG.A standard ECG is formed of a series of ridges and furrows.

In this, P-wave indicates the impulse of contraction generated by S. A. Node which causes Atrial Depolarization and hence, Atrial Systole or Atrial Contraction.These impulses spread over both the atria.The interval PQ represents Atrial Contraction (0.1 second).

QRS-wave indicates the spread of impulse of contraction from A.V. Node to the

wall of ventricles causing Ventricular Depolarization which causes Ventricular

Systole or Ventricular Contraction, immediately after Q.The RS of QRS-wave and ST interval represents Ventricular Contraction (0.3s seconds).T-wave represents the relaxation (repolarization) of ventricles.So ECG is formed of both Depolarization and Repolarization waves.

The P, R and T waves are above the base line of ECG and are called Positive

Waves while Q and S waves are below the base line and are called Negative

Waves.

ECG is record of electrical disturbances in cardiac muscle fibres during the heartbeat.Its P-wave represents atrial Heart disorders include Hypertension

(persistent high blood pressure).Angina (acute chest pain due to decreased depolarization)QRS-wave represents ventricular depolarization (contraction) while T-wave represents ventricular repolarization (relaxation).

SIGNIFICANCE OF ECG:Any abnormality in the working of the heart changes the wave pattern of ECG and can be interpreted by a trained physician to diagnose a particular disorder.The technique to detect the abnormalities of the heart like high blood pressure,rheumatic heart, and congenital heart defects, suspected myocardial infarction,etc. with the help of ECG.

ECG also indicates the rate of heart beat as indicated by number of QRS

complexes that occur in a given time period.ECG can also be used to measure the size and the position of the heart

chambers.ECG can also be used to detect the effects of certain drugs and the function of implanted pacemaker, if any.

COMMON DEFECTS OBSERVED IN ECG AND THEIR

DIAGNOSTIC SIGNIFICANCE:

- Enlargement of P-wave indicates enlargement of atria.

- PQ interval lengthens during rheumatic fever and arteriosclerotic heart

diseases due to inflammation of atria and AV-node.

- In myocardial infarction,( Heart Attack) Q and R waves are enlarged.

- In acute myocardial infarction, the S-T segment is elevated.

- If T-wave is flattened, it indicates insufficient oxygen supply to the heart

muscles as in atherosclerotic heart disease.

LET US KNOW WHAT WE HAVE LEARNT!!

PART: A VERY SHORT ANSWER TYPE QUESTIONS:

|. MULTIPLE CHOICE QUESTIONS:

1. P-wave represents:

a) Atrial depolarization

b) Ventricular depolarization

c) Ventricular repolarization

d) None of the above

2. QRS-wave represents:

a) Atrial depolarization

b) Ventricular depolarization

c) Ventricular repolarization

d) None of the above

3. T-wave represents:

a) Atrial depolarization

b) Ventricular depolarization

c) Ventricular repolarization

d) None of the above

4. Electrocardiograph was discovered by:

a) Einthoven

b) Waller

c) Land Steiner

d) Harvey

5. Full form of ECG is:

a) Electrocardiogram

b) Electrocardiograph

c) Electrocardiography

d) None of the above

ll. TRUE/FALSE:

1. Any abnormality in the working of heart changes the wave pattern of ECG.

2. ECG is record of electrical disturbances in cardiac muscle fibres during the heartbeat.

3. ECG taken when the patient is lying down is called stress ECG.

lil. FILL UPS:

1. Astandard ECG is formed of a series of and .

2. Most modern clinical electrograph used is .

ANSWER KEY: PART-A

MULTIPLE CHOICE QUESTIONS:

1. a) Atrial Depolarization (P-wave indicates the impulse of contraction generated by S.A.node which causes atrial depolarization which causes atrial systole.

2. b) Ventricular Depolarization

(QRS-wave indicates the spread of impulse of contraction from A.V.node to the wall of ventricles causing ventricular depolarization which causes ventricular systole immediately after Q.)

3. c) Ventricular Repolarization (T-wave represents the relaxation (repolarization) of ventricles. )

4. a) Einthoven (Electrocardiograph was discovered by Einthoven)

5. a) Electrocardiogram (A graphic record of the electrical activity of the heart is called electrocardiogram (ECG) or EKG.)

ll. TRUE/FALSE:

1. True

(Any abnormality in the working of the heart changes the wave pattern of ECG and can be interpreted by a trained physician to diagnose a particular disorder. )

2. True

3. False

(ECG taken when patient is lying down is called resting ECG.)

lil. FILL UPS:

1. Ridges and Furrows

2. Pen Recorder

PART: B SHORT ANSWER TYPE QUESTIONS:

1. What is the significance of ECG?

2. Write differences between T-wave and P-wave.

3. What are the common defects observed in ECG?

PART: B LONG ANSWER TYPE QUESTIONS:

1. Explain Electrocardiography in detail.

A190

RECAPITULATION:Dear students, we have studied the chapter 18 - Body Fluids & Circulation,in the previous Daily Dose assignments from DD178 to 189.

Now we will revise the whole chapter in brief.

CIRCULATION helps in transportation of nutrients, nitrogenous wastes,

respiratory gases, hormones for uniform distribution.

BLOOD VASCULAR SYSTEM consists of Blood, Blood Vessels, &Heart.

BLOOD VESSELS are of three types: Arteries, Veins & Blood Capillaries.Arteries have oxygenated blood and carry blood from heart to body parts while deoxygenated blood returned to heart by the veins.

CIRCULATORY PATHWAYS OF TWO TYPES:

OPEN CIRCULATORY PATHWAY in which blood finally comes in sinuses or lacuna which together for a large blood filled cavity called Haemocoel.

CLOSED CIRCULATORY PATHWAY in which blood remains inside the blood vessels.

ABO BLOOD GROUP SYSTEM:There are four types of blood groups in human:

A blood group has A -antigen and b-antibody.

B blood group has B- antigen and a -antibody.

AB blood group has both A & B antigens but no antibody.

blood group has 0 artigen but both a & b antibody.Person with AB blood group is universal recipient, while person with O blood group is universal donor.

Rh BLOOD GROUP has two types:Rh positive has Rh factor while Rh negative is without Rh factor.Incompatibility develops when a Rh+ baby develops in Rh- mother .The first child of Rn- mother will not suffer, but Rh+ blood of foetus stimulate the formation of anti Rh- factors in the mother’s blood which cause death of baby from second pregnancy onward.This is called as

BLOOD CLOTTING:It is a defence mechanism to prevent excess bleeding from the injuries asblood changes into gel state. It involves three steps:Conversion of prothrombin to thrombin Activation of fibrinogen to fibrin

Polymerization of fibrin to form blood clot.

SINGLE CIRCULATORY SYSTEM: (Two chambered heart) in which blood passes only once through heart. Such Animals have deoxygenated blood in the heart. So it

is known as venous heart. e.g. Fishes.

INCOMPLETE DOUBLE CIRCULATORY SYSTEM: (Three chambered heart ) in which oxygenated and deoxygenated blood gets mixed in the ventricles.e.g.amphibians and reptiles.

DOUBLE CIRCULATORY SYSTEM: (Four chambered heart) in which oxygenated and deoxygenated blood do not get mixed and distributed to different parts separately.

HUMAN HEART:It lies in mid thoracic cavity between the lungs.It is surrounded by pericardium.It has 4 chambers: 2 auricles and 2 ventricles.Auricles are separated by inter-auricular septum while ventricles are

separated by inter-ventricular septum.

Right auricle receives deoxygenated blood from various body parts by vena

cava and sends blood to right ventricle through aperture guarded by tricuspid

valve.Left auricle receives oxygenated biood from the lungs through pulmonary

vein and sends blood to left ventricle through aperture guarded by bicuspid

or mitral valve.Right ventricle sends venous blood to lungs through pulmonary arch, while Bases of arch are guarded by semilunar valves.

CONDUCTING SYSTEM OF MYOGENIC HEART:

itis an intrinsic system where by are to

contract , but can be accelerated or

depressed by nerve impulses initiated in the brain and by circulating hormones.

S. A. Node is a mass of special cells in the right atrium which can initiates the

impulse more rapidly. So it is called PACEMAKER.A.V. Node is a mass of cells present near atrio-ventricular valves. It is stimulated by nerve impulses that sweep over atrial myocardial. It can initiate own impulse but at slow rate. It is called PACESETTER of heart.BUNDLE OF HIS is mass of fibres originating from AV node.and brings

CARDIAC CYCLE:It is the event during which one heartbeat or one cycle of contraction and relaxation of cardiac muscle occurs.

It is completed in about 0.8 seconds and is formed of 3 phases:Atrial systole (0.1 sec.), Ventricular systole (0.3 sec.), and Joint diastole (0.4 sec }Due to these phases, blood flows unidirectional and backflow of blood is prevented

by valves.

HEARTBEAT:It is the rhythmic contraction and relaxation of heart.An adult healthy human has heartbeat 72 times per minute to pump approximately 5 litres of the blood.

HEART SOUNDS: These canbeheard by’ ~ .

LUB sound occurs at due to rapid closing of bicuspid and tricuspid valves.DUBB sound occurs at due to rapid closing of semilunar valves.

ELECTRO-CARDIO-GRAPH:It is the machine used to record electrocardiogram.

ELECTRO-CARDIO-GRAM (ECG):It is the record of electrical activities in cardiac muscles fibres during the heartbeat.P-wave represents QRS-wave represents

T-wave represents

DOUBLE CIRCULATION:It includes two types of circulation. covers lesser distance from the lungs to the heart. Systemic circulation covers greater distance from

heart to body parts.

LYMPHATIC SYSTEM:It is formed of lymph, lymph capillaries, lymph vessels and lymph nodes.Lymph nodes are sites of formation of lymphocytes and phagocytosis.

HEART DISORDERS:evs s+ — Acute chest pain due to decreased blood supply to heart.

wi sre Persistent high blood pressure.

Copier ye salaiy free —Due to atherosclerosis of coronary arteries.

Reduced pumping effect of heart.

PART-A VERY SHORT ANSWER TYPE QUESTIONS:

A. MULIPLE CHOICE TYPE QUESTIONS:

Q1. Pacemaker of heart is:

a) AV Node

b) Bundle of His

c) SA Node

d ) Ventricle

Q2. Purkinje fibres are found in: