Blood platelets are small, non-nucleated cells derived from megakaryocytes that play a key role in blood clotting and repairing injuries in blood vessels. The coagulation process prevents excessive bleeding through a series of events involving activated platelets and clotting factors, ultimately forming a stable fibrin clot. Abnormalities in this system can lead to severe complications such as hemorrhage or excessive clotting, necessitating careful monitoring of individuals with clotting disorders.

2. • Blood platelets (or thrombocytes) are very small, 2-4 μm in diameter,
non-nucleated, membrane-bound cells derived from the cytoplasm of
megakaryocytes in the red bone marrow.
• Each megakaryocyte can produce 2,000–5,000 platelets
• Even though platelets like RBCs have no nucleus, their cytoplasm is
packed with granules containing a variety of substances that promote
blood clotting.

3. • Platelets promote blood clotting and help repair minor
tears or leaks in the walls of small blood vessels,
preventing loss of blood from the microvasculature.
• A normal platelet count in human ranges from 150,000 to
450,000 platelets per microliter of blood.
• The life span of platelets is between 8 and 10 days, and
those not used in clotting are destroyed by macrophages,
mainly in the spleen.

4. Blood Clotting
Process

5. • Blood flows through the blood vessels to deliver
the needed oxygen and nutrients to the different
cells in the body.
• The blood clotting process or coagulation is an
important process that prevents excessive
bleeding in case the blood vessel becomes
injured.
• It plays a crucial role in repairing blood vessels.

6. • Bleeding occurs when there is a break in a blood vessel wall.
• Control of bleeding (hemostasis) begins when platelets in the
blood become activated (change shape and develop spines)
and stick to the injured area.
• The platelets form a mesh with blood cells, collagen, and other
proteins.
• This mesh, strengthened by long strands of insoluble fibrin,
entraps more platelets and blood cells, producing a clot that
plugs the break.
• The clot dissolves as the blood vessel heals.

7. What is Blood Clotting?
• Otherwise known as blood clotting,
coagulation plays a pivotal role in the repair of
blood vessels.
• The heart pumps blood throughout the body
with the aid of the arteries, and in turn, blood
goes back to the heart through the veins.

8. • When the blood vessels become injured, it will
trigger the blood clotting process.
• This way, the body will repair the damage to stop
hemorrhage or bleeding from happening.
• For instance, the damage happens in the lining of
the blood vessels, the platelets will form an initial
plug on the affected area.
• They will initiate the clotting process with the aid
of certain clotting factors produced in the body.

9. What are Clotting Factors?
• Clotting factors are components found in
plasma that are linked to the blood clotting
process.
• These factors are named and numbered based
on their discovery.
• Though there are a total of 13 numerals, there
are only 12 clotting factors.
• Factor VI was discovered to be part of another
factor.

10. The clotting factors are
• Factor I (fibrinogen),
• Factor II (prothrombin),
• Factor III (tissue thromboplastin or tissue factor),
• Factor IV (ionized calcium),
• Factor V (labile factor or proaccelerin),
• Factor VII (stable factor or proconvertin), and
• Factor VIII (antihemophilic factor).

11. Additionally, the coagulation factors also include
• Factor IX (plasma thromboplastin component
or the Christmas factor),
• Factor X (Stuart-Prower factor),
• Factor XI (plasma thromboplastin
antecedent),
• Factor XII (Hageman factor), and
• Factor XIII (fibrin-stabilizing factor).

12. • The liver uses vitamin K to produce some of
the factors such as Factors II, VII, IX, and X.
Normally, vitamin K can be consumed through
the diet from plant and animal sources.
• The normal flora of the intestine also
produces vitamin K.

13. Blood Clotting Process
• Hemostasis is a way of the body to stop
injured blood vessels from bleeding. One of
the most important parts of hemostasis is
clotting of the blood.
• Subsequently, the body needs to control the
mechanisms to control and limit clotting.

14. • These include dissolving excess clots that are
not needed anymore.
• When there is an abnormality in any part of
the system that controls bleeding, it can lead
to hemorrhage or excessive clotting.
• These are potentially life-threatening.

15. • Too much clotting can lead to stroke and heart
attacks because blood clots can travel and
stopped the vessels.
• On the other hand, poor clotting can lead to
severe blood loss even with just a slight injury
to the blood vessels.

16. Hemostasis has three major processes namely the
constriction of blood vessels,
• activity of the platelets, and
• activity of the proteins found in blood (clotting
factors).
Injury
• The first phase of the blood clotting process is
injury or when a blood vessel becomes damaged.

17. • This can be in the form of a small tear in the
blood vessel wall that may lead to bleeding.
Blood Vessel Constriction
• The body will constrict the blood vessel to
control blood loss. It will limit the blood flow
to the affected area.
Platelet Plug
• In response to the injury, the body activates
platelets.
• At the same time, chemical signals are
released from small sacs in the platelets to
attract other cells to the area.

18. • They make a platelet plug by forming a clump
together.
• A protein called the von Willebrand factor
(VWF) helps the platelets to stick together.
Fibrin Clot
• When a blood vessel becomes injured, the
coagulation factors or clotting factors in the
blood are activated.
• The clotting factor proteins stimulate the
production of fibrin, which is a strong and
strand-like substance that forms a fibrin clot

19. • For days or weeks, this fibrin clot strengthens
and then dissolves when the injured blood
vessel walls close and heal.
Blood clotting is a crucial process that can help
prevent blood loss due to injury.
If there is an abnormality in any part of the
process, it can lead to dangerous complications
such as severe blood loss.
Commonly, people with clotting disorders are
closely monitored to prevent injuries and
bleeding.

20. Thank You
13rd
January,
2022