The circulatory system transports oxygen, nutrients, hormones and removes waste through a network of tubes called arteries, veins, lymph and capillaries. Blood is composed of plasma and cellular components like red blood cells, white blood cells and platelets. The circulatory system exchanges oxygen, food and carbon dioxide between blood in the capillaries and tissues through diffusion and hydrostatic pressure gradients across the capillary walls.

1. Composition
and
Function
CIRCULATORY SYSTEM

2. • circulatory system consists of the
circulatory medium and a system of
tubes.
• Circulatory medium: blood, lymph and
tissue fluid.
• System of tubes: arteries, veins, lymph
vessels and capillaries

3. Function of circulatory system:
transport oxygen and nutrients to different
body cells.
removes carbon dioxide and other waste
products from the body.
Carries hormones from their site of origin
to distant target tissues.

5. BLOOD
• Blood is a fluid connective tissue.
• Plays an important role in the maintenance
and regulation of pH and body temperature.
• Protects our body from pathogens and
foreign substances.
• The average adult body has approximately
about 5 to 6 litres of blood.

6. 55% plasma
45% cellular components.

8. Plasma
It is the yellow liquid part of the blood
The plasma from which the
protein fibrinogen has been
removed is called serum.

10. A myth: Why do vampires drink blood?
Some vampires use blood as medication—an
iron-rich supplement to
combat blood conditions such as anemia.
For them, consuming blood is a quality of life
issue and is necessary for sustaining their
energy.

11. Class work
Q1. List down two functions of blood.
Q2. Blood is a fluid …………….tissue.
Q3. The blood is composed of about 55%
………… and ………% cellular components
Q4. Cellular components includes …….. ,
…………and ……………
Q5. ………is the yellow liquid part of the blood
Q6. The plasma from which the protein
fibrinogen has been removed is called …………
Q7. Mention any TWO functions of Plasma.

12. Cellular components (Formed elements)

14. RBC/ Erythrocytes
• Size: 7-8 micron
• Shape: Biconcave disc shaped body with a
central depression
• Constitutes about 60% of the blood volume.
• The cell is without a nucleus or mitochondria
• Contain a red pigment called haemoglobin.
• Haemoglobin helps to transport oxygen and
carbon dioxide in blood
• Constitutes about 60% of the blood volume.
• Life span: 120 days and is destroyed in the
spleen

15. • The main function of RBCs is :
• Transportation of oxygen from the lungs to
tissues, and carbon dioxide from tissues to the
lungs.
Production of red blood cells
• produced in the bone marrow of the bones.
• controlled by a hormone called erythropoietin.
• No nucleus so that they can easily change
shape and fit through the various blood vessels
in the body.
RBC/ Erythrocytes

16. • The percentage of red blood cells volume
to the total blood volume is called
hematocrit.
• Normal blood count of RBC is 4.5 to 5.5 per
mL in adult human.
• The normal average is about 46% in male, and
42% in female.
• An increase in hematocrit is called
polycythemia
Hematocrit = % of RBCs

17. • Decrease in hematocrit is called anemia.
• If the blood count of RBC is less than the
normal value, then it is due to some deficiency
like low level of oxygen in blood cells,
deficiency in iron, vitamin B12, blood loss and
other infections.

18. Q8. The red pigment present in erythrocyte is
called………..
Q9. RBC is biconcave shape with no nucleus. Explain.
Q10. Life span of RBC is……., and is destroyed in
the………
Q11. What is the main function of RBCs?
Q12. RBC is produced in…………
Q13. the hormone that controls the production of RBC
is…………
Q14. How do you calculate hematocrit?
Q15. An increase in hematocrit is called ………..
and decrease in hematocrit is called ……….

19. WBCs/ Leukocytes
• Produced in the bone marrow of
the bones and lymph nodes
• irregular in shape with a nucleus
• Part of the immune system that destroys
infectious agents called pathogens
• Have ability to move in and out of the blood
vessels
• Size: 10-12 microns
• Life span: 12 hours to
12 days.

20. Types of Leukocytes

22. Phagocytosis: The
destroy and digest of
virus and bacteria
by engulfing them in
by WBCs.

25. Identify the following:
1. Stain dark red with eosin.
2. Releases chemical histamine during inflammatory
reactions.
3. Protect against the blood borne pathogens.
4. The nucleus is generally of half -moon shaped or
kidney shaped
5. Nucleus is 3 to 5 lobed.
6. Produce antibodies to attack and destroy virus and
bacteria.
7. The process that destroy and digest virus and
bacteria by engulfing them in is called……………

26. Production of WBCs
• White blood cells are mostly produced in bone marrow
and few produced in lymph nodes and spleen.
• Produced more during the time of injury and
infections.
• Normal WBC counts: 6,000 to 9,000 per cubic mL of
blood.
• Overproduction of WBCs is caused due to inflammatory
disease like - anemia, leukemia
• Lesser production of WBC can be due to bone marrow
deficiency and exposure to radiations.

27. Activity I
• Label the cells A to G

28. Did you get all correct???

29. Blood platelets (Thrombocytes)
• Shape: small, oval or round structures, non-
nucleated.
• Size: 2 to 3 microns
• Lifespan: 3 to 5 days.
• The total count of platelets
is about 2,00,000 to
3,00,000 per mL of blood.
• Platelets are small fragments of giant cells
called megakaryocytes
• Production is controlled by a hormone called
thrombopoietin

30. Clotting of blood
• Platelets play vital role in blood clotting.
At the site of injury, they disintegrate and
release a chemical substance known as
thrombokinase, which initiates the process
of clotting.
• Platelets normally remain inactive in the
blood until they reach the damaged
tissue.
• Once activated, platelets change into a
spiny ball shape and become very sticky
and stick on to the damaged tissues.

31. • Heparin- a protein present in blood plasma
prevents the blood clotting during normal
condition.
• A condition in which blood fails to clot
is known as haemophilia.

32. What did you learn?
1. A giant cell called ………….... breaks into small
fragments to form blood platelets.
2. A condition in which blood fails to clot is
known as ………….
3. Production of platelet is controlled by a hormone
called ………………
4. A protein present in blood plasma prevents
the blood clotting during normal condition is………
5. Platelets do not have nucleus (T/F).
6. Blood platelets is also called as leukocyte (T/F)

33. Blood clotting Mechanism

36. Class Work
1. Cell fragments that formed from the rupture of a
megakaryocyte are called…………….
2. The ions responsible for the process of blood clot
is……………..
3. A plasma protein important for blood clotting
is………….
4. A condition in which blood fails to clot is
known as ………….
5. …………..is the chemical substance produced by
platelets at injury site.
6. Main function of platelets is……………….
7. Explain blood clotting in your own words.

37. ABO System
• Blood groups are classified into four major
blood groups determined by the presence or
absence of two antigens: A and B.
• Antigens are the protein on the surface of a
RBC membrane.
• The proteins produced by lymphocytes in
response to the presence of antigens is
called antibody. Antibody A and B.
• The main role of the antibody is to attack
foreign antigens.
• The four kinds of blood groups are A, B, AB
and O.

41. Rh (Rhesus) factor
• Another group of antigens found on the
red blood cells
• People who have these antigens are said
to be Rh positive (Rh+), whereas those
who do not are Rh negative (Rh-).
• Rh- person can develop Rh+ antibodies
upon receiving blood from Rh+ person.

42. Blood Transfusion
• Blood transfusions are done through intravenous line
to replace blood lost during surgery or due to serious
injury/illness.
• Mixing unrelated blood from two individuals can lead
to blood clumping or agglutination. The clumped red
cells can crack and cause toxic reactions. This can
have fatal consequences.

43. Blood Types Explained - A, B, AB and O | Red Cross Blood Services
Rh+ person can receive blood from any other blood
type but a person with Rh- person can receive blood
from Rh– persons only.

45. Review questions
4.The blood group that lacks antigen on the RBC membrane is………..

46. Questions
1. Following a motor vehicle accident, a patient
is rushed to the emergency department with
multiple traumatic injuries, causing severe
bleeding. The patient’s condition is critical,
and there is no time for determining his blood
type. What type of blood is transfused, and
why?
2. A drop of blood from a blood donor is mixed
with serum from a group A person and serum
from a group B person. The donor's red cells
clumped in the A serum but not in the B

47. Exchange of substances
between capillaries and tissue

48. • Artery carry blood away from the heart and veins carry
blood towards the heart.
• Oxygen, food and carbon dioxide are exchanged between
the blood and the organ cells by diffusion.
• Tissue fluid is similar to plasma but its lacks proteins.
• Tissue fluid collects carbon dioxide and other excretory
substances.
• Fluid exchange is controlled by blood pressure within the
capillary vessel and osmotic pressure of the blood.

49. • The osmotic pressure is produced by high
concentrations of salts and plasma proteins
in the blood.
• The pressure exerted by fluids, such as blood
and tissue fluid, against the walls of the
capillaries is called hydrostatic pressure/blood
pressure.
• The source of the hydrostatic blood pressure is
the pumping action of the heart.

52. Revision questions
1)……………..is the pressure exerted by fluid in an
enclosed space against the capillaries wall.
3) The plasma proteins suspended in blood cross
the capillary cell membrane and enter the tissue
fluid via diffusion. True or False? Explain your
thinking.