PSL301H1 Lecture Notes - Lecture 6: Heparin, Megakaryocyte, Factor Ix

• School: UTSG
• Department: Physiology
• Course: PSL301H1
• Professor: Michelle French

Document Summary

Platelets are cell fragments produced in the bone marrow from huge cells known as megakaryocytes: develop this large size by undergoing dna replication up to 7 times without nuclear or cytoplasmic division. Platelets are smaller than red blood cells, are colourless and have no nucleus (they are only fragments of cells): they have a mitochondria, however, allowing them to perform aerobic metabolism. Platelets also contain granules filled with cytokines and growth factors: these chemicals can help promote healing. Always present in the blood and typical half-life is ~10 days. Best known for role in stopping blood loss, but they can also act as immune cells and mediators of the inflammatory response. Thrombopoietin (tpo) is the cytokine that regulates the growth and maturation of megakaryocytes, thus increasing platelet numbers; produced primarily in the liver. Outer edges of the marrow megakaryocytes extend through endothelium into lumen of marrow blood sinuses, where the cytoplasmic extensions fragment into disk-like platelets.