Platelets are commonly recognized as the clear part of blood. They are small, clear fragments of cell with an irregular shape. They do not have a nucleus that contains DNA and have a life span of 5-9 days. Platelets have a number of important functions in the body and a disorder or disease of the platelets can cause either bleeding or clotting. The article will detail the functions of the platelets in the body.
What are the functions of the platelets?
The main function of the platelets is hemostasis. Hemostasis is the process by which bleeding is stopped within the body. Platelets are instrumental in blood clotting and thus stopping the flow of blood. Without an adequate number of platelets excessive bleeding will occur. If the platelet count is too high then blood clots can occur. Blood clots lead to the obstruction of blood flow and can cause stroke, heart attacks, pulmonary embolism or the block of blood to extremities such as arms and legs.
Platelets are also responsible for the release of specific growth factors that help in the repair of connective tissues. When damage occurs to cells, platelets bind to the wound site and form clumps. The platelet clumps bind with a chemical called fibrinogen and create a thin barrier of protein. This creates the initial blood clot. Platelets then excrete growth factors that cause the fibroblasts from the surrounding area to grow and heal the damage. The clumping platelets are then dissolved by specialized enzymes. This happens over a number of days and the pulling of the clot slowly closes the cell walls so that they meet together and heal. This process is called clot retraction.
Research has also shown that platelets help to reduce initial inflammation after injury. They do this by secreting inflammatory mediators known as cytokines and chemokines. They also secrete platelet derived growth factor which regulates the growth and division of cells, particularly blood cells.