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1. Introduction TO HEMA 2 LEC ( Platelets)
Medical Technology (BSMT1)
Emilio Aguinaldo College
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Introduction to Hematology II
Blood vessels
Arteries Carries oxygenated blood away blood from the heart. Arterioles Small arteries Capillaries Changes between the blood and tissues happens. Where the exchange between the oxygen from the RBC’s and carbon dioxide from the cell of the tissues Exchange of glucose and other nutrients Venules Small veins Veins Carries deoxygenated blood away from the tissues
Blood vasculature
Composed of 3 main layers:
1. Tunica interma/tunica intima “inner” most layer Made up of Endothelial cells and has a smooth surface in order to facilitate better blood flow. 2. Tunica media “middle” layer Made up of Smooth muscle and it is the reason why our blood vessels constrict or dilate one of the reasons is
o Prostacyclin is vasodilator- chemical or a substance that possess vasodilation). o Endothelin - is a substance that causes vasoconstriction meaning endothelin excretes a substance. 3. Tunica externa/tunica adventitia “outside” layer Made up of fibers and other fibrous connective tissues.
Vasodilation A phenomenon in which the blood vessel widens to increase the blood flow. Usually happens during infection Examples: pimples Vasoconstriction A phenomenon in which the lumen of the blood vessel becomes narrow in order to decrease the blood flow. To easily attached platelets to the site of injuries Happens in response to injuries
Multipotential hematopoietic stem cell which is the hemacytoblast.
Megakaryopoiesis is mediated by various growth factors which is the Thrombopoietin (TPO) is a protein that stimulates the production of thrombocytes which is made up in the liver and becomes thrombopoietin and it will be transported in the bone marrow via blood vessels and action in the:
- Thrombopoietin stimulate megakaryoblast to proliferate more.
- Thrombopoietin speeds up the maturation process of megakaryopoiesis
Another growth factor is called Megakaryocyte Colony Stimulating Factor (Meg-CSF) it actions and give rise in the parent cells of megakaryocytes which is the Colony Forming Unit Megakaryocyte (CFU- Meg) it is a cell.
Another growth factor: Interleukins 6 Doesn’t stimulate the production of megakaryocyte directly.
Function: It is a protein and stimulates the production of TPO and increase the production of higher Megakaryopoietin Activity (MA)
Megakaryopoiesis Maturation series of a hematological cell that is committed for the production of platelets. Undergoes “endomitosis” o A type of mitosis in which only the chromosomes divide. PRIMARILY REGULATED BY THROMBOPOIETIN Process taken 5-7 days Bone marrow: 7 days to spleen for 2 days after that to peripheral blood for 8-10 days
Megakaryopoiesis- biggest cell inside the bone marrow
As the cell mature, the following happen: Cell size: increase Size of nucleus- increases Granules- absent to present N:C ratio- decreases Cytoplasmic protrusions- absent/ few to present - appendages: when they detached to megakaryocyte that is what we called platelets Produces:2,000-4,000 platelets
Megakaryopoiesis- MK
Lifespan: 7-10 days Shape: biconvex, discoid or irregular Reference range: 150,000-450,000/ul o Thrombocytopenia-less than o Thrombocytosis-more than o If >500 no symptoms and the capability is stop bleeding o >750,000 it may lead to thrombosis o <100 matagal mag stop ang bleeding
Platelets Structure
Hyalomere- non granular part of the platelet Granulomere- composed of granules
Ultra-Structure of the platelet
Peripheral zone- outer most layer of the platelet Sol-gel zone- responsible for the shape of the platelet Organelle zone - a place where organelles and granules are located Membrane system - composed of the dense tubular system
Peripheral zone PLASMA MEMBRANE Glycoproteins 1b and 2b/3a which act as receptors for von Willebrand factor
GLYCOCALYX Fuzzy coating that surrounds the platelet Responsible for the negatively charge of the platelet plasma membrane
SUBMEMBRANOUS AREA Where receptors for adp, collagen, Serotonin, and various coagulation factors are located
Sol-gel zone
Microfilaments Responsible for the discoid shape of the platelet Microtubules Facilitates the changing of the shape of the platelets during platelet activation Contains thrombopoietin, a contractile protein which participates in platelet aggregation clot retraction.
Actomyosin - Actin and myosin are combined
Organelle zone
Mitochondria - responsible for the production of energy/adp Alpha granules - platelet activation Dense granules - platelet activation
Lysosomal granules- suicide bag of the cell and contains digestive enzymes
Membranous system
Dense tubular system Holds calcium (important in secondary hemostasis) for platelet activation Synthesizes prostaglandins (vasodilator)
Open canaliculi system Acts as a canal or passageway of the different secretory products of the platelet
References: 1 Hematology: clinical principles and applications (5th edition) by Elaine keohane 2 hematology: theory and practice (6h edition) by mary turgeon 3’s Hematology and oncology (3rd edition) by dan longo
1. Introduction TO HEMA 2 LEC ( Platelets)
Course: Medical Technology (BSMT1)
University: Emilio Aguinaldo College
