Platelets are tiny colorless disk-shaped particle that are usually found in large quantities that flows freely in our blood and plays important role in the clothing process when damaged blood vessels are identified. For example, when a cut occurs in an individual, the platelets bind the spot of the injured or damaged vessels by providing clotting and thus, prevent continuous bleeding.
The average life span of the platelets ranges between 5 to 9 days and the numbers of platelets required in the body should be on the normal side i.e. ranges from 150,000 to 450,000 for each micrometer of blood. However, when the number of platelets is above normal which is 450,000, it is seen or regarded as a condition called thrombocytosis caused by abnormal cells in a person’s bone marrow as a result of diseases such as anemia, cancer and infection. While having less than 150,000, is a condition called thrombocytopenia and it is caused by high alcohol intake, kidney dysfunction, leukemia and inherited conditions.
Platelets such as platelet-derived growth factor also known as (PDGF), a strong chemotactic agent, TGF beta, vascular endothelial growth factor, fibroblast growth factor and epidermal growth factor are the main sources of growth factors that help in stimulating cellular growth, cellular differentiation and proliferation in mammals. These growth factors that occurred as a result of platelets are usually proteins or steroid hormones which also help in regulating other types of cellular processes. However, platelets also help in the maintenance of hemostasis by the formation of thrombi, when there are damages in the endothelium of the blood vessels.
Apart from the temporary blood clot provided by the platelets, it also engages in wound vessels repair by secreting chemicals that helps increase the invasion of fibroblasts from nearby connective tissues into the injured area for complete healing or to form a scar. The plasmin and fibrinolytic enzyme gradually dissolves the impeded clot, and the platelets are receded by phagocytosis.
The platelets also help in cytokine signaling by positioning itself in spots where injury had occurred, and perhaps in a possibly modulated inflammatory process and by relating with leukocytes and secreting inflammatory mediators such as cytokines and chemokines.
Platelets help in clot retraction which is the reduction of a blood clot over some numbers of days by bringing together the edges of the blood vessels wall in order to repair again, the damages caused by the injury. However, before clot retraction can occur, there must be a discharge of multiple coagulation factors from the platelets stuck at the fibrin mesh of the clot. In this regards, the inability to retract can be caused by conditions such as thrombocytopenia or Thrombasthenia.
REFERENCES:
http://en.wikipedia.org/wiki/Platelet#Other_functions
http://www.hopkinsmedicine.org/heart_vascular_institute/clinical_services/womens_cardiovascular_health_center/patient_information/health_topics/platelets.html
