W1 LECT 4: platelets Flashcards
where are platelets formed?
megakaryocytes in the bone marrow
how does megakaryocytes differentiate?
hematopoietic stem cell- megakaryocyte progenitor cells - mature megakaryocyte
what helps with facilitating fragmentation of
proplatelets into 1 to 2 μm
platelets?
-shear and turbulent blood flow
how many platelets does each megakaryote give rise to?
2000- 3000 platelets
what is the T1/2 of platelets?
9-10 days
what clears the platelets?
liver and spleen
what is thrombopiotein?
primary regulator of platelet production
what regulates the circulating levels of TPO?
clearance of TPO after it
binds to c-mpl receptors on
circulating platelets
what is thrombocytopenia?
Thrombocytopenia is a medical condition characterized by a lower than normal number of platelets in the bloodstream.
what is the treatment for thrombocytopenia?
TPO receptor agonist
outline the structure of platelets?
Extremely small
(3um by 0.5um)
* High level in
circulation-range
150-400x109
platelets/l
* discoid
* anucleate cells
but have distinct
mitochondria
what maintains the discoid shape of platelets?
cytoskeleton
* protects the cell from getting sheared in the blood stream
what are the 3 types of platelet storage granules?
- alpha granules
- dense granules
- lysosomes
how does platelet promote hemostasis?
-Adhesion to sites of vascular injury
* Granule release
* Aggregation to form a platelet plug, and
* providing a procoagulant surface for activated CF on their phospholipid surfacemembrane
what makes platelets active following damage to the vessel wall?
thrombin
