Circulatory System made easy for class 8 and above grade 6

1. Circulatory System
ARUSH DEEP
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2. Circulatory System
in Human Beings
In human being is present a very
well developed closed type of
circulatory system.
Blood vascular system can be
studied in three parts
Circulatory
System
Blood
Blood
Vessels
Heart
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3. Blood
SEC - I
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4. Blood
Blood is a bright red (when oxygenated ) and dark red (when deoxygenated) coloured fluid.
It forms about 8 – 10 % of the body weight of a vertebrate.
It is saltish in taste, slightly alkaline in nature, heavier than water and viscous sticky fluid.
It always keeps on circulating through blood vessels.
The heart pumps blood into arteries and it is returned to the heart through the veins.
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5. Composition of Blood
Blood
PLasma
Water Blood Protein
Albumin
Globulin
Fibrinogen
Prothrombin
Antibodies
Salts
Other
Substances
Food
Respiratory
Gases
Excretory
Process
Hormones
Formed
Elements
RBCs WBCs
Agranulocytes
Monocytes
Lymphocytes
Granulocytes
Acidophils
Basophils
Neutrophils
Platelets
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6. PLASMA
Plasma is a straw - coloured fluid part of the blood.
It is sticky and slightly heavier than water.About
90% of plasma is made up of water.
They also contain proteins, salts, hormones, waste
materials.
FORMED (CELLUAR) ELEMENTS
These are the shaped structures visible under the
microscope.
They are cells and cell like structures present in
blood. They form 42 to 45 % of blood.
They are of three types:
 RBCs
 WBCs
 Platelets
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7. Red Blood Cells (RBCs)
They are also known as erythrocytes.
They contain haemoglobin which has iron. The red colour of RBCs is
because of haemoglobin. It helps in the tranfer of gases to and from
the heart.
Mature red blood cells are minute, biconcave and disc shaped. They
lose their nucleus to increase the space for haemoglobin.
RBCs are made inside the the bone marrow and are destroyed in
the liver. They have a life span of 120 days.
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8. White Blood Cells (WBCs)
They are also known as leucocytes.
They fight against germs and other foreign bodies and protect us against diseases.
WBCs are colourless and they have a neucleus. They are larger than RBCs but fewer in
number.
They are made in the bone marrow. They live for a few hours depending upon the type.
When they travel along the blood, they are flattened and continuous change their shape
along the inner walls of blood vessels.
These amoebatic movement which helps them to squeeze out of capillaries is known as
diapedesis.
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9. Types of WBCs
AGRANULOCYTES
These WBCs have no granules in the cytoplasm
and are produced in the bone marrow.
They are of two kinds:
 Lymphocytes: which have round nucleus
 Monocytes: which have horse-shoe shaped
nucleus.
GRANULOCYTES
These WBCs have larger granules in their
cytoplasm and lobed nucleus
They are of three kinds:
 Neutrophils: have 2-6 lobes of nucleus
 Basophils: have bilobes or irregular nucleus
 Eosinophils: have bilobed nucleus.
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10. Platelets
Thay are also known as thrombocytes.
They help in clotting of blood in the site of injury. They help prevent
blood loss.
They are made in bone marrow and have a life span of 7-14 days.
There are about 2.5 lakh blood platelets in 1 cubic millimeter of
blood.
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11. Function of Blood
Blood carries oxygen from the lungs to the different part of the body and removes carbon-dioxide from the body
cells.
Blood carries digested food from the intestine to all parts of the body.
Blood contains WBCs which protect the body from diseases.
Blood carries hormones from the endocrine glands to different parts of the body.
Blood carries a waste product called urea from the liver to the kidneys for excretion in the form of urine.
Blood regulates body temperature.
Blood carries platelets which form a clot around wound thus preventing blood loss.
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12. Blood Groups
The ABO system of blood grouping was discovered by Karl Lansteiner and in 1931, he won the Novel Prize
for his works on blood groups.
Blood groups are created by molecules present on the surface of red blood cells (and sometimes other
cells as well). Antibodies are proteins produced by certain white blood cells in response to a
foreign substance, the antigen.
Each antibody can bind only to a specific antigen. The purpose of this binding is destroy the antigens.
Antibodies are foreign substances that when introduced into the body, cause immune system to create an
antibody.
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13. The antigen are present on the red blood cells while the
antibodies are present in plasma. There are two types of two
types of antigen and two types of antibodies.
Antigen are Antigen-A and Antigen-B. The antibodies are Anti-A
and Anti-B.
Based on the compatibility, four blood groups have been
recognised in the human being. There are A, B, O and AB
blood groups.
The antigen and antibody of each type of blood group is
summaried in the table.
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Blood
Group
Antigen
RBC
Antibody
Plasma
Donate
to
Receive
from
A A Anti-B A and AB A and O
B B Anti-A B and AB B and O
AB A and B Nil AB only All groups
O Nil
Anti-A and
Anti-B
All groups O only

14. Blood Transfusition
In case of serious blood loss arsing as a result of injuries and various diseases and in serious forms of
anaemia, transfusion of blood is the only wayin which lives can be saved.
A person who donates blood is called the donor and the one who receives is called recipent.
Transfusing a patient with the wrong ABO blood group can be fatal.
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15. Blood
Vessels
SEC -II
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16. Arteries
Arteries are vessels which carry blood away from the heart.
All arteries except pulmonary arteries carry pure blood.
They are eleastic with narrow lumen.
Arteries branch into small arteries called arterioles and end
in capillaries.
Arteries are deeply situated and their lumen is without valves.
The blood in the arteries flows under pressure and with jerks.
This Photo by Unknown author is licensed under CC BY-SA.
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17. Veins
Veins carry blood back to heart.
All veins except pulmonary veins carry impure blood.
These are less eleastic with wider lumen.
Small veins are called venules, which are formed from capillaries and join to
form veins.
Veins are superficially situated and can be seen from the surface of skin.
The veins have a pocket shaped valvesto prevent the back flow of blood.
The blood flows smoothly through the veins.
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18. Capillaries
Cappilaries are fine blood vessels which connect the arrteries and
veins.
Arteries branch to form arterioles. Arterioles further branch to form
capillaries.
Cappilaries reunite to form the venules. And venules reunite to
form veins.
The walls of cappilaries is formed of a single layer of (endothelial)
cell, which lies in close contact with body tissues.
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19. Heart
SEC - III
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21. Heart
The human heart is the size of a clenched fist. It is a muscular organ which rhythmically contracts to force
the blood around.
The circulation of blood is initiated by the heart which lies between the lungs slightly towards the left side.
It is enclosed by a double membrane called pericardium. It is formed of four chambers. The two anterior
chambers which receive blood are called auricles and the two posterior chambers distributing blood are
called ventricles.
In the chambers there are valves which allow the blood to flow in one direction only. The reverse flow of
blood is prevented by the valves.
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22. Valves in the Heart
1. Right auriculo-ventricular heart (Tricuspid Valve): It is located between the right auricle and the right
ventricle.
2. Left auriculo-ventricular heart (Mitral or Bicuspid Valve): It is located between left auricle and the left
ventricle.
3. Pulmonary semilunar valve: It is located at the opening of pulmonary artery.
4. Aortic semilunar valve: It is located at the opening at the opening of aorta.
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23. The Heartbeat
 In the heart cycle of man, there are two sounds which can be heard.
§ Diastole: Diastole is the brief period in the heart cycle when both atria and ventricles are relaxed and the blood refills
with blood from the heart.
§ Systole: Systole is the phase of heart cycle when the heart contracts.
 Diastole and Systole produce an unmistakbale two-tone sound which is easily heard by through an
instrument called the stethoscope. This sound is called heartbeat.
 In a healthy adult, the heart beats an average of 72 times a minute but this can vary from 60 to 80 times
a minute.
 Exercise makes the heart beat faster, bringing more blood to the muscles which is good for health.
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24. Pacemaker
 We have heard about a machine called the "pacemaker", which is
inserted in the heart patient whose heart does not beat
normally.
 Pacemaker takes place of the specialised muscle cells that
initiate heartbeat and which in the patient have stopped
functioning.
 Thus the beating of heart is controlled by the pacemaker (also
called sinoatrial node), which is group of special nerve cells in
the right atrium.
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25. Working of
Heart
The right auricle receives deoxygenated
blood from all parts of the blood with the
help of main vein.
Blood is poured into the right ventricle
from the right auricle and then send to
lungs for oxygenation. From the lungs,
blood is poured into the left auricle.
This circulation is called pulmonary
circulation.
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26. Heart Septum
The dividing wall between the right and left
sides of the heart is the septum.
The potion of heart that separates the right and
left artia of the heart is termed as atrial or
interatrial septum wheras, the portion of
septum which lies between the right and left
ventricles of the heart is called the venticular or
interventricular septum.
Function of septum:
•To separate two sections of the heart because
left side of the heart receives and pump
oxygebated blood while the right part and
pumps deoxygenated blood to lungs for
oxygenation.
•The blood cannot be deoxygenated if the
septum is not present.
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