Question 1

Question 1Define the following terms:(a) Circulatory system(b) Blood(c) Heart(d) Diapedesis(e) Phagocytosis(f) Rh factor

Accepted Answer

(a) Circulatory system — The circulatory system is a network consisting of blood, blood vessels and the heart. This network supplies tissues in the body with oxygen and other nutrients, transports hormones and removes unnecessary waste products.(b) Blood — Blood is the circulating fluid contained in the heart and in the blood vessels such as arteries, veins and capillaries of the circulatory system. Blood from the heart is pumped throughout the body using blood vessels.(c) Heart — The heart is made of specialized cardiac muscle tissue that allows it to act as a pump within the circulatory system. Heart pushes the blood around the body and has different chambers such as right atrium, left atrium, right ventricle, left ventricle to prevent the mixing of oxygenated blood and carbon dioxide rich blood.(d) Diapedesis — Diapedesis is the squeezing of leucocytes through the wall of capillaries into the tissues.(e) Phagocytosis — Phagocytosis is the process in which most WBCs and particularly the neutrophils engulf particle-like solid substances, especially bacteria.(f) Rh factor — Rh factor is an inherited antigen often found on the blood cells. Some individuals have these antigens and are thus Rh positive (Rh+) while others who do not have this antigen are Rh negative (Rh-)

Question 2

Question 2Distinguish between the following pairs on the basis of words indicated in the brackets ( ):(a) Erythrocytes and Leukocytes (Nucleus)(b) Leukocytes and Thrombocytes (Life-span)(c) Arteries and Veins (Wall and lumen)(d) Pulmonary and Systemic circulation (Kind of blood)(e) Mitral valve and Tricuspid valve (Location)

Accepted Answer

(a) Difference between Erythrocytes and Leukocytes (Nucleus):CharacterErythrocytesLeukocytesNucleusAbsentPresent(b) Difference between Leukocytes and Thrombocytes (Life-span):CharacterLeukocytesThrombocytesLife spanTwo weeks3-5 days(c) Difference between Arteries and Veins (Wall and lumen):CharacterArteriesVeinsWallThick and muscularThin and less muscularLumenNarrowWider(d) Difference between Pulmonary and Systemic circulation (Kind of blood):CharacterPulmonary circulationSystemic circulationKind of bloodPulmonary artery brings deoxygenated blood to lungs and pulmonary vein takes oxygenated blood from lungs to heart.Oxygenated blood is transported to body parts from heart and deoxygenated blood is transported back to heart.(e) Difference between Mitral valve and Tricuspid valve (Location):CharacterMitral valveTricuspid valveLocationPresent between left atrium and left ventricle.Present between right atrium and right ventricle.

Question 3

Question 3Give reasons/explain:(a) The left ventricle has thicker walls than the right ventricle.(b) The walls of right ventricle are thicker than those of the right auricle.(c) Vitamin K is essential for the process of blood clotting.(d) A mature mammalian Erythrocyte lacks nucleus, mitochondria and endoplasmic reticulum.(e) People have a common belief that the heart is located on the left side of the chest.

Accepted Answer

(a) The left ventricle pumps blood to the farthest points in the body such as the feet, the toes and the brain against the gravity while the right ventricle pumps the blood only up to the lungs. Therefore, the left ventricle has thicker walls than the right ventricle.(b) The right ventricle pumps blood to the lungs for oxygenation whereas the right auricle receives the blood from venae cavae and passes it to the right ventricle. Therefore, walls of the right ventricle are thicker than those of the right auricle.(c) Vitamin K acts as a catalyst that transforms some anti-clotting proteins, which are always present, into clotting proteins when there is a cut or wound to the body. The mechanism of blood clotting involves the presence of calcium and other clotting factors. Thrombokinase activates an enzyme called prothrombin activator. The enzyme prothrombin activator then converts plasma protein prothrombin into thrombin. Thrombin is the enzyme which in turn converts fibrinogen into fibrin. Polymerized fibrin together with platelets forms a clot at the wound site. The prothrombin is a plasma protein synthesized in the liver. Vitamin K is essential for the synthesis of prothrombin. Hence, Vitamin K is essential for the process of blood clotting.(d) Lack of nucleus, mitochondria and endoplasmic reticulum helps erythrocytes in the following way:Loss of nucleus makes the red cells biconcave, thus increasing their surface area to absorb more oxygen.Loss of mitochondria means that they cannot use the absorbed oxygen themselves.Absence of endoplasmic reticulum makes it flexible so that they can move through fine capillaries.(e) The heart is right in the center between the two lungs and above the diaphragm. The narrow end of the roughly triangular heart is pointed to the left side and during working, the contraction of the heart is most powerful at this end giving a feeling that the heart is on the left side.

Question 4

Question 4Write important role/roles of the following:(a) Tonsils(b) Spleen(c) Hepatic portal vein(d) Basophils(e) S.A.N.

Accepted Answer

(a) Tonsils — Tonsils are lymph glands located on the sides of the neck. They tend to localize the infection and prevent it from spreading it in the body as a whole.(b) Spleen — The spleen is a large lymphatic organ. The spleen acts as a blood reservoir in case of emergency such as haemorrhage, stress or poisoning. It produces lymphocytes and destroys worn out RBCs.(c) Hepatic portal vein — The hepatic portal vein is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents.(d) Basophils — Basophils are a type of white blood cells. They are the least common type of granulocyte which release chemicals called histamine for inflammation which dilate blood vessels.(e) S.A.N. — The sinoatrial node (SAN) is a region of cardiac fibres located in the right atrium. The electrical wave of stimulation is initiated here and extends over the two atria, causing them to contract. It is often referred to as the pacemaker of the heart.

Question 5

Question 5What is meant by the term 'Double circulation'? Distinguish between the two types of circulation in our body.

Accepted Answer

Double circulation is a process during which blood passes twice through the heart during one complete cycle. The flow of blood in the heart consists of two phases —The short pulmonary (lung) circulationThe long systemic (general body) circulationDifference between pulmonary and systemic circulation —Pulmonary circulationSystemic circulationIt involves circulation of blood between the heart and the lungs.It involves circulation of blood between the heart and the body organs (except lungs).It carries deoxygenated blood to the lungs to receive oxygen.It carries oxygenated blood to the body organs.It returns oxygenated blood back to the heart.It returns deoxygenated blood back to the heart.

Question 6

Question 6Write the main steps in coagulation of blood in their correct sequence?

Accepted Answer

Coagulation of blood (or clotting) occurs in a series of steps as follows:The injured tissue cells and the platelets which disintegrate at the site of the wound release a substance thrombokinase (also called thromboplastin).The thrombokinase acts as an enzyme and with the help of calcium ions present in the plasma, it converts a substance prothombin (inactive) of the plasma, into thrombin (active). Vitamin K, a fat-soluble vitamin is essential for the production of prothombin.Thrombin in the presence of calcium ions reacts with the soluble fibrinogen of the plasma to convert it into insoluble fibrin. Fibrin is a solid substance that forms threads. These microscopic threads of fibrin are sticky and form a mesh or network at the site of wound.Blood cells are trapped in the network of the fibrin; the network then shrinks and squeezes out the rest of the plasma which is in the form of a clear liquid, the serum. The solid mass which is left behind is called clot (or thrombus).

Question 7

Question 10The kind of cells that initiate blood coagulation:MonocytesLymphocytesLeukocytesThrombocytes

Accepted Answer

ThrombocytesReason — Thrombocytes, also known as platelets form the plug at the site of injury and initiate blood coagulation.

Question 8

Question 11A human heart has four chambers and four valves to regulate the process of blood circulation in the body. What kind of phases would occur when blood is supplied to Aorta and Pulmonary Artery from the chambers of the heart ?Atrial systole and ventricular diastole.Ventricular systole and Atrial diastole.Right ventricular systole and left ventricular diastole.Left atrial systole and right atrial diastole.

Accepted Answer

Ventricular systole and Atrial diastoleReasonWhen blood is supplied to aorta and pulmonary artery the ventricles contracts in order to pump blood out of the ventricles, meanwhile the atria relaxes and receives blood from vena cava and pulmonary vein.

Question 9

Question 12Pramod met with an accident while going to his office. Consequently, he lost a large volume of blood. His blood group is 'AB'. Which of the following blood groups can be donated to him ?A and B onlyAB onlyA, B and AB onlyA, B, AB and O

Accepted Answer

A, B, AB and OReasonA person with blood group AB has both A and B antigens and no antibodies, hence they can receive blood from any blood group.

Question 10

Question 7Given diagram is a schematic representation of the circulatory system in humans. Study the same and answer the questions that follow :(a) Label the parts 1 and 4 indicated in the diagram.(b) Which of the above mentioned number is the thickest artery? Also write its name.(c) Mention the number and chamber of the heart which has the thickest muscular wall.(d) Which of the above numbers/structures has the maximum number of blood capillaries?(e) Draw neat and labelled diagrams of the transverse section of vena cava and the part numbered as 3. Make sure to show the structural differences between these two in the diagram.

Accepted Answer

(a) Parts 1 and 4 are:1 → Right Auricle4 → body parts(b) 3, Aorta(c) 2, Left ventricle(d) Lungs(e) Labelled diagrams of the transverse section of vena cava and aorta showing their structural differences are given below:

Question 11

Question 8Given alongside are diagrams of a certain category of blood vessels showing the role of a special structure in their walls. Study the figure and answer the questions that follow.(a) Name the kind of blood vessels shown in the figure. What are its branches termed as ?(b) Name the structure shown inside the blood vessels. Write its important role.(c) What kind of blood flows through these blood vessels normally? Name the blood vessel which carries blood from the heart to the lungs.(d) Name a similar kind of blood vessel which is related to the liver and kidney.(e) Draw a neat and labelled diagram of the transverse section of the blood vessel shown above showing the three layers of its wall and lumen.

Accepted Answer

(a) The kind of blood vessels shown in the figure is vein. Its branches are termed as venule.(b) The structure shown inside the blood vessels are valve. Its role is to prevent the backflow of blood.(c) Deoxygenated blood flows through these blood vessels normally. The blood vessel which carries blood from the heart to the lungs is the pulmonary artery.(d) Hepatic vein and renal vein are related to Liver and Kidney respectively.(e) Below diagram shows the transverse section of a vein with the three layers of its wall and lumen labelled:

Question 12

Question 9Given below is a diagram of the external features of the human heart. Study the figure and answer the questions that follows :(a) Label the guidelines shown as 1 to 6 in the figure.(b) Write the important role of parts 5 and 6.(c) Name the chamber of the heart which collects blood from the lungs through a blood vessel. Also write the name of the blood vessel.(d) Write one structural and one functional difference between the blood vessels 4 and 5.(e) What happens when there is a blockage in any coronary artery or any of their branches?

Accepted Answer

(a) Labelled guidelines are:1 → Aortic Arch2 → Left atrium3 → Left ventricle4 → Aorta5 → Inferior vena cava6 → Superior vena cava(b) Inferior vena cava transports deoxygenated blood from the posterior or the lower region of the body (including abdomen and legs) to heart and superior vena cava transports deoxygenated blood from the anterior or upper regions of the body (including head, chest and arms) to the heart.(c) Left Atrium collects blood from Lungs. The blood vessel involved is Pulmonary vein.(d) One structural and one functional difference between Inferior vena cava and Aorta is:Inferior vena cavaAortaThin wall and wide lumen.Thick wall and narrow lumen.Transports deoxygenated blood to heart.Transports oxygenated blood from heart to body parts.(e) When there is a blockage in any coronary artery or in any one or more of their branches, there is deadening of the corresponding area of heart muscles leading to myocardial infarction (i.e., heart attack).

The Circulatory System

Descriptive Type

Multiple Choice Type

Structured Application Skill Type