In the process of regeneration of cells in the bone marrow, platelets are formed.These are the cells responsible for clotting function of the blood and for the restoration of the walls of blood vessels.
mature state
Talking about what the life span of platelets, most experts consider only the period when they are identified as a separate structure from the megakaryocyte.A time when they had just formed and mature, do not take into account.
On average, they are in the bloodstream for about a week.But human platelet life span may range from 5 to 12 days.Experts have identified a number of species: young, old, mature and form of irritation.They do not depend on the age of these cells and the characteristics of the system hematopoiesis.
cycle of
all platelets are formed in bone marrow.It begins with the megakaryocyte colony forming units, also called "CFU-Meg."It is divided into mitosis.From her first formed promegakarioblast that goes into megakaryoblasts.
for 4-5 days in the marrow mature special cells - megakaryocytes, whose diameter is about 60-120 microns.They were preceded by a special form of a grain-free basophilic cytoplasm and nucleus polymorphism trend.It's called "promegakariotsit."The mature megakaryocyte cytoplasm are large in size and the availability of grain in her violet-pink color.Kernel it rough, it may be various fanciful shapes.
It is separated from the cytoplasm megakaryocyte small blood cells, resembling the shape of a disk.From this point we can talk about what life span of platelets.One estimates usually only mature forms.Their in healthy humans should be of the order of 90%.
number of cells
To understand why such a concentration in the blood of non-nuclear cells, it is necessary to know not only about what the life span of platelets, but also about how fast and how much they appear.For every kilogram of body weight they have to order 15h106.From each megakaryocyte in the fission process otshnurovyvaetsya about 3000 platelets.Still about 7-17% of the total lung is formed.This is because in the bloodstream are also prothrombocytes.They independently reach microcircular bed light.And already there is a process of release of platelets.
Every day the human body produces about 66 ± 14,6 thousand. Platelets per ml of blood each.In the blood of an adult should counts from 180 to 320h109 of blood cells in children can be from 150 to 450h109.However, when calculating the amount of their age must be considered.For example, infants who are not even 10 days, they can be from 99 to 420h109.
Appearance plates
All mature bull have the same structure.Thus lifespan of platelets in blood can vary.Each of the plates contains a disk-shaped core, but it has a centrally located granulomer which includes azurophil granules.They may be there are between 5 and 20. It is also distinguished by mature platelets lilac gialomeru and with clear boundaries.
diameter of the full cell is about 3-4 microns.They differ oval or circular discoid form.The surface at rest they smooth.However, upon contact with other bodies or foreign bodies from the surface immediately appear filamentous appendages that give them a star-shaped.
structure
addition to the information that the average life span of platelets is about 7 days, it is important to know that in every cell there are three layers.The peripheral zone includes nadmembrannoy zone, the purpose of which lies in the activation of platelets.After it is a membrane that is responsible for adequate and timely reaction of the cells and clotting factors.It is the so-called phospholipid matrix.That it forms koagualyatsionnye complexes.It is also responsible for platelet aggregation and adhesion.
In the area of the sol-gel are mitochondria.Also, there are special channels that connect the outer layer of the membrane.The zone comprises a sol-gel trombostein responsible for the disc-shaped plates.
Separately, experts allocate land organelles.There are 4 kinds of pellets.It is in the process of accumulation of these clotting factors.They operate at all times, regardless of the fact that the lifespan of platelets is 5-12 days.
Said separation zones can be considered in the multiplication of the cells under a microscope.
Lifecycle platelet
After the plates were separated from the blood megakaryocytes they enter the bloodstream.It should be noted that the regulation of this process has been thrombopoietin.It is essential for normal platelet formation and full maturation of the cytoplasm of megakaryocytes.
Approximately 1/3 of the total amount deposited in the spleen.The remaining 70% of the total circulating blood flow.Such a depot is created in the spleen because they are moving in the body slowly.Traversal process takes about 8 minutes.As a result, platelets are released into the bloodstream and move to the place where they are needed.All the problems with the spleen are immediately displayed on the number of blood platelets.However, this does not affect the lifespan of platelets, and changes only their number in the blood.Thus, when removing a spleen their concentration is significantly higher.But with splenomegaly (enlargement of the body), these small cells move through it slowly.This leads to a significant reduction in their number in the blood.
worth noting that participates in the process of recovery vessels, tissue healing and blood clotting, only a small part of the platelets.Other die in the bone marrow, spleen and liver under the influence of macrophages.
