The Circulatory System

A is False and R is True

Explanation
Human beings have a closed blood vascular system i.e., the blood circulates in the body through blood vessels.

Both A and R are True.

Explanation
The left ventricle needs to generate more force during contraction because it must pump blood to distant body tissues. In contrast, the right ventricle only pumps blood to the nearby lungs.

A is False and R is True.

Explanation
The respiratory pigment haemoglobin (Hb) is formed of globin protein and iron containing part called haemin.

A is True and R is False.

Explanation
Basophils contain granules in the cytoplasm and release histamine.

A is False and R is True

Explanation
Prothrombin is the inactive form of thrombin which is produced during an injury for the purpose of blood clotting.

A is True and R is False.

Explanation
In humans, RBCs have specific proteins on their surfaces. These proteins are called antigens.

(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-)

(a) Difference between Erythrocytes and Leukocytes (Nucleus):

(b) Difference between Leukocytes and Thrombocytes (Life-span):

(c) Difference between Arteries and Veins (Wall and lumen):

(d) Difference between Pulmonary and Systemic circulation (Kind of blood):

(e) Difference between Mitral valve and Tricuspid valve (Location):

(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:

1. Loss of nucleus makes the red cells biconcave, thus increasing their surface area to absorb more oxygen.
2. Loss of mitochondria means that they cannot use the absorbed oxygen themselves.
3. 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.

(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.

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 —

1. The short pulmonary (lung) circulation

2. The long systemic (general body) circulation

Difference between pulmonary and systemic circulation —

Coagulation of blood (or clotting) occurs in a series of steps as follows:

1. The injured tissue cells and the platelets which disintegrate at the site of the wound release a substance thrombokinase (also called thromboplastin).
2. 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.
3. 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.
4. 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).

(a) Pulmonary artery

(b) Sides of neck

(c) Centre of chest, between the lungs and above diaphragm

(d) Upper right corner of the walls of the right atrium

(e) Between liver and stomach, intestine

Erythrocytes

Reason — Erythrocytes (RBC) contain haemoglobin which transports oxygen to different parts of the body.

Spleen

Reason — Spleen releases stored blood during emergency like haemorrhage and emotional stress.

Phagocytosis

Reason — Phagocytosis is the mechanism by which neutrophils engulf particle (germs).

Renal artery

Reason — Renal artery brings blood to kidney for purification (removal of nitrogenous waste).

Carboxyhaemoglobin

Reason — Haemoglobin combines with carbon dioxide to form Carboxyhaemoglobin. In lungs it releases carbon dioxide to combine with oxygen and forms oxyhaemoglobin.

Antitoxins

Reason — Antitoxins are released by Eosinophils. It neutralise the toxins.

Pericardium

Reason — Pericardium forms the double layered protective covering of heart.

Capillary

Reason — Capillaries are very narrow tubes with no muscles and allow diffusion of substances into and from the tissues.

Hepatic portal vein

Reason — Hepatic portal vein carry blood from the stomach and intestine to the liver.

Thrombocytes

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

Ventricular systole and Atrial diastole

Reason

When 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.

A, B, AB and O

Reason

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

Blood and Lymph

Conventionally, all veins are shown in blue colour and all arteries are shown in red colour. But pulmonary vein and artery are exceptions to it. The pulmonary artery is shown in blue as it contains deoxygenated blood and pulmonary vein is shown in red colour because it contains oxygenated blood.

Oxygen, Carbon dioxide, Digested food and Hormones are the four substances transported by blood.

(i) Plasma

(ii) Haemoglobin

(iii) Nuclei, Mitochondria

(iv) Diapedesis

(i) 120 days

(ii) 4.5 million

(iii) Granular & Non-granular

(iv) Leukocytes

(i) False
Corrected Statement — Process of coagulation starts with the release of a substance from platelets.

(ii) True

(iii) False
Corrected Statement — The solid fibrin and thrombin are different. Thrombin converts fibrinogen into insoluble fibrin in presence of calcium ions.

(iv) True

(i) Vitamin K

(ii) Haemophilia, Dengue

(iii) Antibody A and B

(iv) Rhesus (common monkey)

(i) Ventricles have thick walls when compared with those of auricles.

(ii) Ventricles give rise to two large blood vessels called pulmonary artery and aorta.

(i) Tricuspid valve — Right Ventricle

(ii) Mitral valve — Left Ventricle

(iii) Pulmonary semilunar valves — Pulmonary Artery

The pulmonary artery carries deoxygenated blood to the lungs for oxygenation. Hence, it is shown in blue colour in the diagram.

(i) Systole

(ii) Tendinous cords (Chordae tendinae)

Ventricular Systole

(i) The auricles have thin and less muscular walls, and have Cuspid valves to prevent back flow of blood.

(ii) Arteries carry blood to an organ and break up into arterioles ending in capillaries.

(iii) Walls of capillaries consist of a single layer of squamous epithelial cells.

(iv) The substances to and from the tissues diffuse through the walls of capillary.

1. Pulmonary (lung) circulation
2. Systemic (body) circulation

(i) Pulmonary artery — From right ventricle to lungs

(ii) Renal artery — from aorta into kidney

(iii) Posterior vena cava — from lower parts of body into right atrium

(iv) Hepatic vein — from liver into posterior vena cava

(v) Hepatic portal vein — from stomach and intestine to liver

A portal vein is one which starts with capillaries and also ends in capillaries

Pulse is the alternate expansion and elastic recoil of the wall of the artery during ventricular systole.

The normal values of blood pressure in a normal human adult is 100 - 140 mm (systolic) and 60 - 80 mm (diastolic).

Leukocytes

1. Supplies nutrition and oxygen to those parts where blood cannot reach.
2. It drains away excess tissue fluid and metabolites and returns proteins to the blood from tissue spaces.
3. Fats from the intestine are absorbed through lymphatics.

Spleen and tonsils (node) are the main lymphatic organs in humans.

(i) Lymphocyte

(ii) Lacteals

(iii) Tonsils

Structural Differences between White Blood Cells and Red Blood Cells:

The first sound "LUBB" is produced when the atrio-ventricular (tricuspid and bicuspid) valves get closed sharply at the start of ventricular systole. The second sound "DUP" is produced when at the beginning of ventricular diastole, the semilunar valves at the roots of aorta and pulmonary artery get closed.

(a) The parts indicated are as follows —

• 1 → Red Blood Cell (RBC)
• 2 → White Blood Cell (WBC)
• 3 → Blood Platelet
• 4 → Blood Plasma

(b) Two structural differences between red blood cells and white blood cells are:

(c) The main functions of the parts labelled 1, 2 and 3 are as follows:

1. Part 1 (Red Blood Cell) — Transport of respiratory gases to the tissues and from the tissues, transport of nutrients from the alimentary canal to the tissues.
2. Part 2 (White Blood Cell) — WBCs play major role in defense mechanism and immunity of the body.
3. Part 3 (Blood Platelet) — Blood platelets are the initiators of blood clotting.

(d) The average life span of a red blood cell (RBC) is about 120 days.

(e) Fibrinogen.

(a) Leukemia

(b) White Blood cells (WBC)

(c) Two functions of WBC

1. Helps in fighting with infections.
2. Helps in removing damaged tissues and in cleaning up cellular waste.

(a) The structure 3 represents the heart. It forms the centre of double circulation and is located between the liver and the head. Also the blood circulation (indicated by 1) begins from heart to lungs.

(b) The numbers of the structures are mentioned below:

• Aorta → 5
• Hepatic portal vein → 7
• Pulmonary artery → 1
• Superior vena cava → 9
• Renal vein → 8
• Stomach → 10

(a) The blood vessels A, B and C are:

• A → Artery
• B → Vein
• C → Capillary

(b) The parts labeled 1-4 are:

• 1 → External layer made of connective tissue
• 2 → Lumen
• 3 → Middle layer of smooth muscles and elastic fibres
• 4 → Endothelium

(c) Two structural differences between Artery and Vein are:

(d) The kinds of blood that flow through A and through B are:

• A (Artery) → Oxygenated blood
• B (Vein) → Deoxygenated blood

(e) At the capillary level the actual exchange of gases takes place.

(a) The phase is Ventricular Systole and Atrial Diastole.

(b) Ventricular muscles are contracting during this phase because the valves between the two ventricles and pulmonary artery and aorta are open while the atrio-ventricular valves are closed.

(c) The parts numbered 1 to 6 are:

• 1 → Pulmonary Artery
• 2 → Aorta
• 3 → Pulmonary Vein
• 4 → Left Atrium
• 5 → Bicuspid Valve
• 6 → Right Ventricle

(d) Types of blood flowing through parts '1' and '2' are mentioned below:

• Part 1 (Pulmonary artery) → Deoxygenated blood
• Part 2 (Aorta) → Oxygenated blood

(e) Two valves — Bicuspid and Tricuspid valves are closed in this phase.

(a) The cell labelled 1 is a Red blood cell.

(b) Phenomenon occurring in A is Diapedesis.

(c) Two structural differences between red blood cells and white blood cells are:

(d) The process which occurs in B and C is phagocytosis. In this process, the WBCs engulf the foreign particles and destroy them, thus preventing the occurrence of disease.

(a) Parts 1 and 4 are:

1 → Right Auricle
4 → 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:

(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:

(a) Labelled guidelines are:

1 → Aortic Arch

2 → Left atrium

3 → Left ventricle

4 → Aorta

5 → Inferior vena cava

6 → 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:

(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).

(a) Blood platelets → blood coagulation.

(b) Neutrophils → phagocytosis.

(c) Erythrocytes → transportation of gases.

(d) Lymphocytes → Produce antibodies.

(e) Bone marrow → destruction of old and weak RBC's/production of RBCs and WBCs.

(a) Heart, Blood and Blood Vessels

(b) Red blood cells, White blood cells and platelets

(c) Artery, Vein and capillary

(d) Blood, Tissue fluid and Lymph

(e) Synovial fluid, Vitreous humour and Aqueous humour

(f) Spleen and Tonsil

(g) Plasma and cellular elements

(h) Closed Blood Circulation and open blood circulation.

(i) Haemin (iron containing part) and globin protein

(j) Atrial systole and Ventricular systole

(a) Hepatic portal vein

(b) Blood Capillaries

(c) Pulmonary artery

(d) White blood cells

(e) Venules

(f) Portal vein

(g) Atrial systole

(h) Tricuspid valve

(i) Atrial systole

(j) Pericardial fluid

(a) The blood vessel that begins and ends in capillaries is the hepatic portal vein.

(b) A blood vessel which has small lumen and thick wall is artery.

(c) The valve which prevents the back flow of blood in the veins and lymph vessels is pocket-shaped valve.

(d) An anticoagulant present in the blood is heparin.

(a) Lub : Atrio-ventricular valve :: Dup : Semilunar valves

(b) Coronary artery : Heart :: Hepatic artery : Liver

(c) RBCs : Polycethemia :: WBCs : Leukemia

(d) WBCs : Leukopenia :: RBCs : Erythropenia

(e) Chest pain : Angina pectoris :: Heart attack: Myocardial infarction