Alpha granules
, (α-granules) also known as platelet alpha-granules are a cellular component of platelets. Platelets contain different types of granules that perform different functions, and include alpha granules, dense granules, and lysosomes.
Which are the two types of granules found in platelets?
Platelets contain three major granule types—
dense granules, α-granules, and lysosomes
—although other granule types have been reported. Dense granules and α-granules are the most well-studied and the most physiologically important.
What is found in dense granules of platelets?
granules: the alpha granules, the dense granules, and the lysosomes. Each of these granules is rich in certain chemicals that have an important role in platelet function. For example, dense granules contain large quantities of
calcium ions and adenosine diphosphate (ADP)
.
What is in platelet alpha granules?
Platelet Secretion
Growth factors stored in α-granules include
vascular endothelial growth factor (VEGF)
, platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), hepatocyte growth factor (HGF), and insulin-like growth factor (IGF).
How many types of granules are there in platelets?
Platelets contain
three
granule types: α-granules, dense granules, and lysosomes (Figure 1; Table 1). Absence of dense granules, as observed in inherited syndromes such as Hermansky–Pudlak syndrome or Chediak–Higashi syndrome, results in a bleeding diathesis (Hermansky and Pudlak, 1959).
What do platelet granules do?
Platelet α–granules function
in inflammation both by expressing receptors that facilitate adhesion of platelets with other vascular cells and by releasing a wide range of chemokines
. Adhesive interactions generally result in mutual activation and in the propagation of the inflammatory phenotype of each cell.
What is a normal platelet count for a woman?
What is a healthy platelet count? A normal platelet count ranges from
150,000 to 450,000 platelets per microliter of blood
. Having more than 450,000 platelets is a condition called thrombocytosis; having less than 150,000 is known as thrombocytopenia.
What’s the lifespan of platelets?
Platelets are small parts of cells. Their main function is to control bleeding. They make up a very small part of your blood (less than 1%). The lifespan of platelets is
about 9 to 12 days
.
What is GREY platelet syndrome?
Gray platelet syndrome is
a bleeding disorder associated with abnormal platelets
, which are small blood cells involved in blood clotting. People with this condition tend to bruise easily and have an increased risk of nosebleeds (epistaxis).
What do Lambda granules contain?
Lambda granule is another type of granules in platelets and belongs to the lysosomal type organelles. Like lysosomes in other cell types, lambda granule contain
enzymes necessary in protein, lipid and carbohydrate degradation process
.
What happens during platelet adhesion?
Platelet adhesion is an essential function in response to vascular injury and is generally viewed as the first step during which
single platelets bind through specific membrane receptors to cellular and extracellular matrix constituents of the vessel wall and tissues
.
How do platelets get activated?
Platelet activation represents a central moment in the process that leads to thrombus formation.
When endothelial damage occurs, platelets come into contact with exposed collagen and von Willebrand factor
, becoming activated. They are also activated by thrombin or by a negatively charged surface, such as glass.
What shape are platelets?
Resting platelets are
small discoid shapes
around 1.5–3 μm in size. The cytoskeleton of platelets mainly consists of actin, tubulin, spectrin and filamin. Spectrin, which has a two-dimensional web-like structure, laminates the cytoplasmic side of the plasma membrane, both ends of which are connected to actin filaments.
What is megakaryocyte?
Megakaryocytes are
cells in the bone marrow responsible for making platelets
, which are necessary for blood clotting.
What is granule secretion?
Granules secretion in gonadotropes, as in other secretory cells, is a
mechanism
that uses the secretory vesicle synaptotagmin as a Ca
2 +
sensor and is mediated by SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) proteins as effectors.
What happens in thrombocytosis?
Thrombocytosis is a condition in which
there are an excessive number of platelets in the blood
. Platelets are blood cells in plasma that stop bleeding by sticking together to form a clot. Too many platelets can lead to certain conditions, such as stroke, heart attack or a clot in the blood vessels.
