Tag: biology

Only mammals have platelets, tiny cells without nuclei that are responsible for plugging the leaks in the blood vessels. Other animals use more conventional systems of hemostasis. Some marine invertebrates have a single type of blood cell, responsible for hemostasis, but also for other types of defences. Non-mammalian vertebrates have specialized nucleated thrombocytes to do the job.

Platelets are small, non-nucleated cells that are derived from megakaryocytes in the bone marrow. Platelets circulate in the blood, sense damage to a blood vessel and accumulate at these sites, where they initiate blood clotting. They are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow.

Only mammals have Platelets. Non-mammals possess thrombocytes which are nucleated cells which have been shown to have a haemostatic function paralleling that of mammalian platelets.

A megakaryocyte is a large bone marrow cell with a lobated nucleus responsible for the production of blood thrombocytes (platelets), which are necessary for normal blood clotting.

Under normal physiological conditions, every 100 ml of oxygenated blood delivers approximately 5 ml of oxygen to the tissues. Therefore, 1 liter (1000 ml) of oxygenated blood delivers about 50 ml of oxygen.

The ornithine cycle (urea cycle) is a metabolic pathway that converts toxic ammonia into urea, which is then excreted by the kidneys.

Platelets, also called thrombocytes, are blood cells whose function is to stop bleeding. The average life span of circulating platelets is 7 to 10 days.

Platelets, also called thrombocytes, are blood cells whose function is to stop bleeding. Platelets have no nucleus: they are fragments of cytoplasm, which are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid structures. They are smallest of the three major blood types. They make up a tiny portion of the blood volume.

Life span of platelets is 8 - 9 days. Platelets, also called thrombocytes, are blood cells, whose function is to stop bleeding. Platelets have no nucleus: they are fragments of cytoplasm, which are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid structures. Life span of individual platelets is controlled by the internal apoptotic regulating pathway. Old platelets are destroyed by phagocytosis in the spleen and liver.