Thrombocyte Physiology by Dr.M.Anthony David MD

NOMAD:2006:BP:ThrombocytesNOMAD:2006:BP:Thrombocytes 11

THROMBOCYTES:THROMBOCYTES:PLATELETSPLATELETS

ByBy

Dr.M. Anthony David, MDDr.M. Anthony David, MD

Professor of PhysiologyProfessor of Physiology


THROMBOCYTES: INTROTHROMBOCYTES: INTRO

Normally Normally 1.5 - 4.0 1.5 - 4.0 Lakhs/Cu.mmLakhs/Cu.mm in blood.in blood.

Are Are 2 – 4 2 – 4 µµ in diameter; in diameter; smallest blood cells.smallest blood cells.

Developed from giant cells Developed from giant cells called called Megakaryocytes.Megakaryocytes.


THROMBOCYTES: STRUCTURE

Spherical, oval, Spherical, oval, or rod-shaped or rod-shaped colorless bodies.colorless bodies.

Diameter is Diameter is between 2 to 4 between 2 to 4 μμ..

Normally under Normally under Electron Electron Microscopy they Microscopy they appear as:appear as:

Flattened discs Having a cell

membrane And a

Cytoplasmic matrix.

Microtubules encircle the thrombocyte just below it’s surface membrane.



Do not have nuclei.Do not have nuclei. Cannot reproduce.Cannot reproduce. But behave functionally as whole But behave functionally as whole

cells.cells. Cytoplasm includes active Cytoplasm includes active

proteins such as:proteins such as:Actin.Actin.Myosin.Myosin.Thrombesthenin.Thrombesthenin.

THROMBOCYTES: THROMBOCYTES: STRUCTURESTRUCTURE


Cell Organelles in thrombocytes Cell Organelles in thrombocytes include:include: Lysosomal granules.Lysosomal granules. Dense bodies: about 50 – 100 in Dense bodies: about 50 – 100 in

number.number. Mitochondria & Enzyme systems Mitochondria & Enzyme systems

which produce:which produce: ATPATP ADPADP

Enzyme systems producing:Enzyme systems producing: Prostaglandins – Local hormones.Prostaglandins – Local hormones.



Fine Glycogen granules.Fine Glycogen granules. Microvesicles.Microvesicles. Microtubules.Microtubules. Filaments.Filaments. Granules:Granules:

Dense: Serotonin, ADP etc.Dense: Serotonin, ADP etc. άά-granules: Clotting factors such as:-granules: Clotting factors such as:

Fibrin Stabilizing Factor (Fibrin Stabilizing Factor (FSFFSF) Factor ) Factor XIIIXIII

PDGFPDGF: Platelet Derived Growth Factor: Platelet Derived Growth Factor

THROMBOCYTES:THROMBOCYTES: Structures within Structures within


Internal Membranous systems:Internal Membranous systems: Open Canalicular System:Open Canalicular System:

Spongelike invaginationsSpongelike invaginations Provide multiple channels for:Provide multiple channels for:

Taking up Calcium ions Taking up Calcium ions Secreting granule contents.Secreting granule contents.

Dense Tubular System:Dense Tubular System: Channels of S.E.R.Channels of S.E.R. Serves as an intracellular store for Serves as an intracellular store for

Calcium ions.Calcium ions.



Platelet PhysiologyPlatelet Physiology

Have a half life Have a half life of 8 – 12 days.of 8 – 12 days.

Eliminated from Eliminated from circulation by circulation by the Tissue the Tissue Macrophage Macrophage system.system.

Thrombocytes Thrombocytes are active are active structures.structures.

About half of About half of them are them are removed by the removed by the Macrophages in Macrophages in the Spleen.the Spleen.

Platelet surface Platelet surface membrane has membrane has Phospho lipids, Phospho lipids, Cholesterol & Cholesterol & glycolipidsglycolipids


THROMBOCYTES: THROMBOCYTES: FUNCTIONSFUNCTIONS

Formation of Formation of Platelet plugsPlatelet plugs in in Hemostasis.Hemostasis. Activation.Activation. Adhesion.Adhesion. Aggregation/ Accumulation.Aggregation/ Accumulation. Cohesion or Plug formationCohesion or Plug formation

Supporting Coagulatory Supporting Coagulatory mechanisms.mechanisms.

Phagocytosis.Phagocytosis. Storage & transport of substances.Storage & transport of substances.


PLATELET PLUG PLATELET PLUG FORMATIONFORMATION

It can by itself stop blood loss, if It can by itself stop blood loss, if the tear is small.the tear is small.

Many such minute ruptures Many such minute ruptures occur thousands of times every occur thousands of times every day in minute blood vessels.day in minute blood vessels.

Platelets manage to plug these Platelets manage to plug these very well, all by themselves.very well, all by themselves.


APPLIED ASPECTSAPPLIED ASPECTS

Thrombocytopenia:Thrombocytopenia: Decrease in Thrombocyte count.Decrease in Thrombocyte count.

(Normal: 1.5 – 4 Lakhs/cu.mm of (Normal: 1.5 – 4 Lakhs/cu.mm of blood)blood)

Critical Thrombocyte Count is Critical Thrombocyte Count is 40,000/cu.mm.40,000/cu.mm.

Causes Causes Purpura:Purpura: Multiple subcutaneous purplish Multiple subcutaneous purplish

blotches.blotches.


IDIOPATHIC THROMBOCYTOPENIC IDIOPATHIC THROMBOCYTOPENIC PURPURAPURPURA

Usually cause not known.Usually cause not known. Called as Called as Idiopathic Idiopathic

Thrombocytopenic Purpura.Thrombocytopenic Purpura. Diagnosis by:Diagnosis by:

Easy bruisability & Purpura.Easy bruisability & Purpura. Critical Platelet count.Critical Platelet count. Prolonged Bleeding Time. Prolonged Bleeding Time.

Can be treated by giving multiple Can be treated by giving multiple transfusions of:transfusions of:

Whole blood Whole blood Platelet rich plasma: Platelet rich plasma: PRPPRP


APPLIED ASPECTS (Contd.)APPLIED ASPECTS (Contd.)

With normal thrombocyte count, With normal thrombocyte count, purpura may occur inpurpura may occur in

Thrombesthenic PurpuraThrombesthenic Purpura, where , where the thrombesthenin is defective.the thrombesthenin is defective.

ThrombocytosisThrombocytosis can cause can cause increased predisposition for increased predisposition for Thrombotic events.Thrombotic events.


PURPURAPURPURA


THROMBOCYTES: A REVIEWTHROMBOCYTES: A REVIEW

One of the three One of the three blood cells or blood cells or formed element.formed element.

1.5 – 4.0 1.5 – 4.0 Lakhs/Cu.mmLakhs/Cu.mm

2 – 4 Microns in 2 – 4 Microns in diameter.diameter.

No nuclei.No nuclei. Have proteins:Have proteins:

ActinActin MyosinMyosin ThrombestheninThrombesthenin

Have granules Have granules secreting:secreting: Serotonin, ADPSerotonin, ADP FSF & PDGFFSF & PDGF

Main function: Main function: Platelet Plug Platelet Plug formation:formation: ActivationActivation AdhesionAdhesion AggregationAggregation Cohesion.Cohesion.

Applied Aspects: Applied Aspects: ITPITP


THANK YOU ALL FOR LISTENING!

Thrombocyte Physiology by Dr.M.Anthony David MD

Education

thrombocytes thrombocytes

purpura nomad

structure nomad

prp nomad

cholesterol glycolipids

platelet physiology

critical platelet count

platelet surface membrane