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Platelets

Platelets

Description:

This lesson will identify the role of platelets in maintaining homeostasis and preventing major blood loss.

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Tutorial

What's Covered

This lesson will cover the role of platelets in clotting by looking at:

  1. Hemostaisis
  2. Blood Clotting Disorders

1. Hemostaisis

Platelets are a component of blood that are involved in clotting and play an important role in hemostasis, or the process that slows or stops bleeding.

Terms to Know

    • Platelets
    • Are also called thrombocytes, platelets are actually cell fragments of bone marrow cells called megakaryocytes. Platelets are used to form blood clots to control hemostasis.
    • Hemostasis
    • The process of controlling/stopping bleeding from a broken vessel; platelets are the main component of hemostasis by working with the plasma protein fibrinogen to form a blood clot.

Imagine there was some sort of injury or tear in a vessel, and blood begins to flow out. If this isn't fixed and too much blood flows out of the vessels, we're going to have an imbalance; homeostasis will not be able to be maintained. Hemostasis will begin:

  • After the tear has happened, the vessel will actually contract or constrict. This restricts the flow of blood through that vessel, resulting in less blood flow out of the tear.
  • Next, platelets will stick to the wall of the vessel. These platelets will essentially help to clog up that tear.
  • Blood will coagulate. This means that it becomes a thicker, almost a gel-like substance.
  • A more permanent blood clot will form.
    • Within your plasma, you have a protein called factor X that will be activated, and then, an enzyme called thrombin will be produced.
    • This enzyme will cause fibrous threads to form, almost like a net. As those fibrous threads form, they trap red blood cells and platelets, helping to clot the tear that's in that vessel.
    • That will start to pull that vessel back together until it can permanently heal

Term to Know

    • Thrombin
    • An enzyme in the blood that plays a critical role in hemostasis by converting the plasma protein fibrinogen into fibrin; fibrin secures platelets as they plug a damaged vessel (platelet plug) and the end result is a clot.

2. Clotting Disorders

There are several different disorders associated with the blood not clotting properly:

Thrombosis is a disorder when a clot forms in an undamaged vessel, and then that clot will stay there. It will affects blood flow through the vessel.

An embolism is related to thrombosis. It's when a clot will form in a damaged vessel, but, instead of staying in that vessel it will actually start roaming throughout the body. This can be very dangerous because it can become stuck in other vessels and affect blood flow to tissues and organs.

A stroke is a clot that blocks blood flow to the brain. This can cause the brain to not receive enough oxygen to be able to function properly.

Hemophilia is a genetic clotting disorder that is inherited. With this disorder blood doesn't clot properly. If a person were to get a cut or tear in their vessel, clots don't form as quickly as they would normally, which can lead to more serious problems. This is especially true if the person is in a very serious accident where they're losing a lot of blood.

Terms to Know

    • Thrombosis
    • The formation of a blood clot within a vessel which obstructs blood flow through the vessel.
    • Embolism
    • A circulating mass in the blood, examples: fatty embolus or an air embolus.
    • Stroke
    • When blood flow is obstructed to an area of the brain causing brain tissue to become ischemic; if blood flow is not immediately restored brain damage will ensue.
    • Hemophilia
    • A group of hereditary disorders that prevent clots from being formed.

Summary

Hemostasis is the process that occurs to stop blood from flowing out from a damaged blood vessel. When a vessel is damaged, it will constrict. Platelets will then stick to the wall of the vessel. Blood will coagulate, and a more permanent blood clot will form. A protein called factor X will cause an thrombin to be produced. This enzyme will cause fibrous threads to form like a net, trapping red blood cells and platelets. Then the vessel will start to pull back together and begin to heal. There are several clotting disorders which can be dangerous to a person. Thrombosis is the formation of a clot in an undamaged vessel that obstructs blood flow. An embolism is a clot that form at a damaged site, but then begins to circulate. A stroke is a clot in the brain and hemophilia is a genetic disorder that prevents blood from clotting correctly.

Keep up the learning and have a great day!

Source: SOURCE: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Platelets

    Are also called thrombocytes, platelets are actually cell fragments of bone marrow cells called megakaryocytes. Platelets are used to form blood clots to control hemostasis.

  • Hemostasis

    The process of controlling/stopping bleeding from a broken vessel; platelets are the main component of hemostasis by working with the plasma protein fibrinogen to form a blood clot.

  • Thrombin

    An enzyme in the blood that plays a critical role in hemostasis by converting the plasma protein fibrinogen into fibrin; fibrin secures platelets as they plug a damaged vessel (platelet plug) and the end result is a clot.

  • Thrombosis

    The formation of a blood clot within a vessel which obstructs blood flow through the vessel.

  • Embolism

    A circulating mass in the blood, examples: fatty embolus or an air embolus.

  • Stroke

    When blood flow is obstructed to an area of the brain causing brain tissue to become ischemic; if blood flow is not immediately restored brain damage will ensue.

  • Hemophilia

    A group of hereditary disorders that prevent clots from being formed.