Circulation is the transport of nutrients, oxygen, CO2 and excretory products to the concerned tissues or organs.
For circulation, simple organisms (sponges, coelenterates etc.) use water from their surroundings. Complex organisms use
body fluids (blood & lymph) for circulation.
CIRCULATORY PATHWAYS
Circulatory system is 2 types- Open and Closed. Types of circulation
§ Open circulatory system: Here, the blood pumped by the Ø Single circulation: In fishes. In this, heart receives impure
heart passes through large vessels into open spaces or blood only (venous heart).
cavities called sinuses. E.g. Arthropods and molluscs.
Deoxygenated blood → to heart → to gills → oxygenated
§ Closed circulatory system: Here, the blood pumped by
blood → to body parts → deoxygenated blood → to heart.
the heart is always circulated through blood vessels. This
Ø Incomplete double circulation: In amphibians & reptiles.
is more advantageous as the flow of fluid can be more
In this, left atrium gets oxygenated blood from gills/
precisely regulated. E.g. Annelids and chordates.
lungs/skin and right atrium gets deoxygenated blood from
All vertebrates have a muscular chambered heart.
other body parts. However, they get mixed up in the single
• Fishes: 2-chambered heart (an atrium + a ventricle). ventricle. It pumps out mixed blood.
• Amphibians: 3-chambered heart (2 atria + a ventricle).
Ø Double circulation: In birds & mammals. Right atrium gets
• Reptiles (except crocodiles): 3-chambered heart (2 atria + deoxygenated blood and passes to right ventricle and left
a ventricle). Ventricle is incompletely partitioned. atrium gets oxygenated blood and passes to left ventricle.
• Crocodiles, birds & mammals: 4-chambered heart.
The ventricles pump it out separately without any mixing up.
HUMAN CIRCULATORY SYSTEM
BLOOD VASCULAR SYSTEM LYMPHATIC SYSTEM
Heart Blood Blood vessels Lymph
Formed elements Arteries Lymph vessels
Plasma
Veins Lymph nodes
RBC WBC Platelets
Capillaries
Granulocytes Agranulocytes
Neutrophils Lymphocytes Monocyte
Oeosinophils
B- Lymphocytes
Basophils T-Lymphocytes
BLOOD VASCULAR SYSTEM
It includes Heart, Blood & Blood vessels. B. FORMED ELEMENTS (RBC, WBC & PLATELETS)
1. BLOOD Red Blood Cells (RBC) or Erythrocytes:
Formed of plasma (55%) & formed elements (45%). - Biconcave non-nucleated cells. No mitochondria, Golgi
A. PLASMA complex etc. Red colour is due to Haemoglobin (iron
containing protein). Normal Hb level is 12-16 g/ 100 ml.
Straw-coloured, slightly alkaline (pH 7.4) viscous fluid.
- Count: 5 - 5.5 millions/ mm3.
Constituents of plasma - Formed in: Red Bone marrow.
• Water (90-92%): It is a good solvent. - Average lifespan: 120 days. Worn-out RBCs are
• Plasma proteins (6-8 %): Include destroyed in spleen (graveyard of RBCs).
o Fibrinogen: For blood coagulation. - Function: CO2 and O2 transports.
o Globulins: Act as antibodies (for defense of the body). White Blood Cells (WBC) or Leucocytes:
o Albumins: For osmotic balance. Regulate blood pressure.
- Colourless nucleated cells.
• Glucose, amino acids, lipids & cholesterol.
- Count: 6000-8000 /mm3.
• Inorganic constituents: Na+, Ca2+, Mg2+, Cl-, HCO3- etc.
- Formed in: Bone marrow, lymph glands, spleen.
• Gases like CO2, O2, N2 etc. - Average lifespan: Generally short lived (1- 15 days).
Plasma without clotting factors is known as Serum. - Function: Part of immune system.
1
, Types of WBC: Granulocytes & Agranulocytes - Antigen A reacts with anti-A. Antigen B reacts with anti-B.
1. Granulocytes - If bloods with interactive antigens & antibodies are mixed
They are 3 types: together, it causes clumping (agglutination) of RBCs.
a. Neutrophils (Heterophils): 60-65%. Soldier of the body. - Persons with O Group are called Universal donors because
Function: Phagocytosis. they can donate blood to persons with any other blood group.
b. Eosinophils (Acidophils): 2-3%. Resist infections. Cause Persons with AB group are called Universal recipients
allergic reactions. because they can accept blood from all groups.
c. Basophils (Cyanophils): 0.5-1%. Secrete histamine, 2. Rh grouping
serotonin, heparin etc. Cause inflammatory reactions. - Rhesus (Rh) factor is another antigen found on RBC.
2. Agranulocytes - Rh+ve means the presence of Rh factor and Rh-ve means
They are 2 types: absence of Rh factor. Nearly 80% of humans are Rh+ve.
a. Lymphocytes (20-25%): Smallest WBC with largest - Anti-Rh antibodies are not naturally found. So Rh-ve
nucleus. Includes B- lymphocytes & T- lymphocytes. person can receive Rh+ve blood only once but it causes the
Cause immune responses. Secrete antibodies. development of anti-Rh antibodies in his blood. So, a second
b. Monocytes (6-8%): Largest WBC. transfusion of Rh+ve blood causes agglutination. Therefore,
Function: Phagocytosis. Rh-group should be matched before transfusion.
Platelets (Thrombocytes): Erythroblastosis foetalis
- Colourless non-nucleated cell fragments. - It is a Rh incompatibility between the Rh-ve blood of a
- Count: 1.5 - 3.5 lakhs /mm3. pregnant mother and Rh+ve blood of the foetus.
- Formed in: Megakaryocytes in Bone marrow. - Rh antigens do not get mixed with maternal blood in first
- Average lifespan: 7 days. pregnancy because placenta separates the two bloods.
- Function: Blood clotting. - But during first delivery, the maternal blood may be
exposed to small amount of foetal blood (Rh+ve). This
induces the formation of Rh antibodies in maternal blood.
- In case of her subsequent pregnancies, the Rh antibodies
from the mother leak into the foetal blood (Rh+ve) and
destroy the foetal RBCs. This is fatal to the foetus or cause
severe anaemia and jaundice to the baby. This condition
is called Erythroblastosis foetalis.
- It can be avoided by administering anti-Rh antibodies to
the mother immediately after the first delivery.
BLOOD COAGULATION 2. BLOOD VESSELS
It is a mechanism for haemostasis (prevention of blood loss Blood vessels are 3 types: Arteries, Veins & Capillaries.
through injuries). At the site of injury, following events occur: § Arteries: They carry blood from heart to other tissues. They
contain oxygenated blood (except pulmonary artery).
Clumped platelets & tissues release thromboplastin → It forms
Their smaller branches are called arterioles. Arteries are 3-
thrombokinase (Prothrombinase) enzyme → Thrombokinase
layered- inner tunica intima (squamous endothelium),
hydrolyses prothrombin to thrombin enzyme in presence of
middle tunica media (smooth muscles & elastic fibres) and
Ca2+ → Thrombin converts soluble fibrinogen to insoluble
outer tunica externa (fibrous connective tissue).
fibrin → Fibrin threads trap dead & damaged blood cells to
§ Veins: They carry blood towards heart. They contain
form clot (coagulum).
deoxygenated blood (except pulmonary vein). Their smaller
BLOOD GROUPS branches are called venules. Veins are also 3-layered but
Blood groups were discovered by Carl Land Steiner. tunica media is comparatively thin.
1. ABO grouping § Capillaries: In tissues, arterioles divide into thin walled and
It is based on presence or absence of 2 surface antigens single layered vessels. They are called capillaries. They
(chemicals that induce immune response) on RBCs namely A unite into venules.
& B. Similarly, plasma contains 2 antibodies (proteins 3. HEART
produced in response to antigens) namely anti-A & anti-B. - It is a mesodermally derived organ located in mediastinum.
Blood Can donate
Can receive - It has the size of a clenched fist.
Antigens Antibodies blood from
group blood to
(Donor’s group)
- It is protected by double-layered pericardium.
A A Anti-B A & AB A, O - The pericardial space (between pericardial membranes) is
B B Anti-A B & AB B, O filled with pericardial fluid. It reduces the friction between
AB A, B Nil AB only A, B, AB & O the heart walls and surrounding tissues.
O Nil
Anti-A & A, B,
O only
- Heart has 4 chambers- two upper atria (auricles) and two
Anti-B AB & O
lower ventricles.
2
For circulation, simple organisms (sponges, coelenterates etc.) use water from their surroundings. Complex organisms use
body fluids (blood & lymph) for circulation.
CIRCULATORY PATHWAYS
Circulatory system is 2 types- Open and Closed. Types of circulation
§ Open circulatory system: Here, the blood pumped by the Ø Single circulation: In fishes. In this, heart receives impure
heart passes through large vessels into open spaces or blood only (venous heart).
cavities called sinuses. E.g. Arthropods and molluscs.
Deoxygenated blood → to heart → to gills → oxygenated
§ Closed circulatory system: Here, the blood pumped by
blood → to body parts → deoxygenated blood → to heart.
the heart is always circulated through blood vessels. This
Ø Incomplete double circulation: In amphibians & reptiles.
is more advantageous as the flow of fluid can be more
In this, left atrium gets oxygenated blood from gills/
precisely regulated. E.g. Annelids and chordates.
lungs/skin and right atrium gets deoxygenated blood from
All vertebrates have a muscular chambered heart.
other body parts. However, they get mixed up in the single
• Fishes: 2-chambered heart (an atrium + a ventricle). ventricle. It pumps out mixed blood.
• Amphibians: 3-chambered heart (2 atria + a ventricle).
Ø Double circulation: In birds & mammals. Right atrium gets
• Reptiles (except crocodiles): 3-chambered heart (2 atria + deoxygenated blood and passes to right ventricle and left
a ventricle). Ventricle is incompletely partitioned. atrium gets oxygenated blood and passes to left ventricle.
• Crocodiles, birds & mammals: 4-chambered heart.
The ventricles pump it out separately without any mixing up.
HUMAN CIRCULATORY SYSTEM
BLOOD VASCULAR SYSTEM LYMPHATIC SYSTEM
Heart Blood Blood vessels Lymph
Formed elements Arteries Lymph vessels
Plasma
Veins Lymph nodes
RBC WBC Platelets
Capillaries
Granulocytes Agranulocytes
Neutrophils Lymphocytes Monocyte
Oeosinophils
B- Lymphocytes
Basophils T-Lymphocytes
BLOOD VASCULAR SYSTEM
It includes Heart, Blood & Blood vessels. B. FORMED ELEMENTS (RBC, WBC & PLATELETS)
1. BLOOD Red Blood Cells (RBC) or Erythrocytes:
Formed of plasma (55%) & formed elements (45%). - Biconcave non-nucleated cells. No mitochondria, Golgi
A. PLASMA complex etc. Red colour is due to Haemoglobin (iron
containing protein). Normal Hb level is 12-16 g/ 100 ml.
Straw-coloured, slightly alkaline (pH 7.4) viscous fluid.
- Count: 5 - 5.5 millions/ mm3.
Constituents of plasma - Formed in: Red Bone marrow.
• Water (90-92%): It is a good solvent. - Average lifespan: 120 days. Worn-out RBCs are
• Plasma proteins (6-8 %): Include destroyed in spleen (graveyard of RBCs).
o Fibrinogen: For blood coagulation. - Function: CO2 and O2 transports.
o Globulins: Act as antibodies (for defense of the body). White Blood Cells (WBC) or Leucocytes:
o Albumins: For osmotic balance. Regulate blood pressure.
- Colourless nucleated cells.
• Glucose, amino acids, lipids & cholesterol.
- Count: 6000-8000 /mm3.
• Inorganic constituents: Na+, Ca2+, Mg2+, Cl-, HCO3- etc.
- Formed in: Bone marrow, lymph glands, spleen.
• Gases like CO2, O2, N2 etc. - Average lifespan: Generally short lived (1- 15 days).
Plasma without clotting factors is known as Serum. - Function: Part of immune system.
1
, Types of WBC: Granulocytes & Agranulocytes - Antigen A reacts with anti-A. Antigen B reacts with anti-B.
1. Granulocytes - If bloods with interactive antigens & antibodies are mixed
They are 3 types: together, it causes clumping (agglutination) of RBCs.
a. Neutrophils (Heterophils): 60-65%. Soldier of the body. - Persons with O Group are called Universal donors because
Function: Phagocytosis. they can donate blood to persons with any other blood group.
b. Eosinophils (Acidophils): 2-3%. Resist infections. Cause Persons with AB group are called Universal recipients
allergic reactions. because they can accept blood from all groups.
c. Basophils (Cyanophils): 0.5-1%. Secrete histamine, 2. Rh grouping
serotonin, heparin etc. Cause inflammatory reactions. - Rhesus (Rh) factor is another antigen found on RBC.
2. Agranulocytes - Rh+ve means the presence of Rh factor and Rh-ve means
They are 2 types: absence of Rh factor. Nearly 80% of humans are Rh+ve.
a. Lymphocytes (20-25%): Smallest WBC with largest - Anti-Rh antibodies are not naturally found. So Rh-ve
nucleus. Includes B- lymphocytes & T- lymphocytes. person can receive Rh+ve blood only once but it causes the
Cause immune responses. Secrete antibodies. development of anti-Rh antibodies in his blood. So, a second
b. Monocytes (6-8%): Largest WBC. transfusion of Rh+ve blood causes agglutination. Therefore,
Function: Phagocytosis. Rh-group should be matched before transfusion.
Platelets (Thrombocytes): Erythroblastosis foetalis
- Colourless non-nucleated cell fragments. - It is a Rh incompatibility between the Rh-ve blood of a
- Count: 1.5 - 3.5 lakhs /mm3. pregnant mother and Rh+ve blood of the foetus.
- Formed in: Megakaryocytes in Bone marrow. - Rh antigens do not get mixed with maternal blood in first
- Average lifespan: 7 days. pregnancy because placenta separates the two bloods.
- Function: Blood clotting. - But during first delivery, the maternal blood may be
exposed to small amount of foetal blood (Rh+ve). This
induces the formation of Rh antibodies in maternal blood.
- In case of her subsequent pregnancies, the Rh antibodies
from the mother leak into the foetal blood (Rh+ve) and
destroy the foetal RBCs. This is fatal to the foetus or cause
severe anaemia and jaundice to the baby. This condition
is called Erythroblastosis foetalis.
- It can be avoided by administering anti-Rh antibodies to
the mother immediately after the first delivery.
BLOOD COAGULATION 2. BLOOD VESSELS
It is a mechanism for haemostasis (prevention of blood loss Blood vessels are 3 types: Arteries, Veins & Capillaries.
through injuries). At the site of injury, following events occur: § Arteries: They carry blood from heart to other tissues. They
contain oxygenated blood (except pulmonary artery).
Clumped platelets & tissues release thromboplastin → It forms
Their smaller branches are called arterioles. Arteries are 3-
thrombokinase (Prothrombinase) enzyme → Thrombokinase
layered- inner tunica intima (squamous endothelium),
hydrolyses prothrombin to thrombin enzyme in presence of
middle tunica media (smooth muscles & elastic fibres) and
Ca2+ → Thrombin converts soluble fibrinogen to insoluble
outer tunica externa (fibrous connective tissue).
fibrin → Fibrin threads trap dead & damaged blood cells to
§ Veins: They carry blood towards heart. They contain
form clot (coagulum).
deoxygenated blood (except pulmonary vein). Their smaller
BLOOD GROUPS branches are called venules. Veins are also 3-layered but
Blood groups were discovered by Carl Land Steiner. tunica media is comparatively thin.
1. ABO grouping § Capillaries: In tissues, arterioles divide into thin walled and
It is based on presence or absence of 2 surface antigens single layered vessels. They are called capillaries. They
(chemicals that induce immune response) on RBCs namely A unite into venules.
& B. Similarly, plasma contains 2 antibodies (proteins 3. HEART
produced in response to antigens) namely anti-A & anti-B. - It is a mesodermally derived organ located in mediastinum.
Blood Can donate
Can receive - It has the size of a clenched fist.
Antigens Antibodies blood from
group blood to
(Donor’s group)
- It is protected by double-layered pericardium.
A A Anti-B A & AB A, O - The pericardial space (between pericardial membranes) is
B B Anti-A B & AB B, O filled with pericardial fluid. It reduces the friction between
AB A, B Nil AB only A, B, AB & O the heart walls and surrounding tissues.
O Nil
Anti-A & A, B,
O only
- Heart has 4 chambers- two upper atria (auricles) and two
Anti-B AB & O
lower ventricles.
2
