Welcome to plateletMAP™, an interactive site where you can learn about platelet interactions and functions in the body, ask questions, contribute knowledge and build a network!
Did you know that you can learn how to take care of your platelets so they can take care of you? The more you know about platelets the better life style choices you can make to protect your platelets so they can protect you.
A person has typically 1 trillion platelets circulating in their blood.
This is based on an average blood volume of 5 liters and an average platelet count of 200,000 per microliter.
Platelets are innate immune cells1 which means that they are our first line defenders against foreign substances or pathogens.
Platelets are also hemostatic/clot forming cells which means they prevent and stop bleeding by filling holes in blood vessels.
When platelets perform their immune and hemostatic functions they use cellular mechanisms known as platelet activation.
Platelets are produced by cells in the bone marrow called megakaryocytes. By default, platelets are created in their resting state and are called resting cells or discoid cells.2
Platelets are a mammalian specialty. They evolved and specialized from amebocytes (e.g., horseshoe crab) to thrombocytes (e.g., bullfrog) to serotonin-containing thrombocytes in warm-blooded animals and finally, platelets in mammals.3
Both resting and activated states of platelets are natural and necessary when platelets fulfill their roles as immune cells and hemostatic cells.
Platelets perform differently in blood vessels, and in communication with other immune cells in the spleen and liver, depending on their activation state.
PLATELET ACTIVATION IS A NECESSARY DUALISM.
Platelets activate in response to stress.
When platelets activate they change their shape, their surface characteristics (they express markers like CD62P, CD40L and Fcγ receptors), and fragment into microparticles.
By releasing microparticles or substances such as serotonin, platelets communicate with other cells or parts of the body.
All of these changes can be measured to determine the activation state of platelets.
WHAT LEADS TO PLATELET ACTIVATION?
Platelets are extremely sensitive and activate at temperatures below 30°C and above 42°C, and in response to high shear forces, pathogens, and many chemicals.
This is necessary for their role as defenders of the body. Wounds, stress and leaky gut lead to platelet activation.
Platelets in the blood of patients suffering from depression are highly activated and contain only half the normal serotonin level—could there be an association between leaky gut and depression?
Platelets are produced by megakaryocytes.
Serotonin is produced and released for platelet uptake.
Animals—including humans—cannot make tryptophan, the precursor of serotonin, but have to ingest it with plant food.
Platelets recognize wounds and defend us against entering pathogens.
Activated platelets are sticky which can lead to thrombosis, heart attack, stroke, and other cardiovascular problems.
Macrophages remove activated platelets.2
Infection can lead to thrombocytopenia—a low platelet count—and splenomegaly—an abnormally large spleeen.