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Thrombocytes
202 - Lec 3: Thrombocytes
| Question | Answer |
|---|---|
| Thrombopoiesis | -Originate in the bone marrow -Endomitosis or Endoreduplication – nuclear division without cytoplasmic division (stays as once cell and it just keeps getting larger; goes through about 2-5 divisions; multinucleated) |
| Where is thrombopoietin produced? | In the liver and kidney |
| Megakaryocyte Development Stages | • Progenitor Cell • Megakaryoblasts • Promegakaryocyte • Mature Megakaryocyte • Productive Megakaryocyte |
| Thrombocyte Life Cycle | • Individual platelets are fragmented and released into circulation • Remaining nucleus is destroyed by macrophages • Remain in circulation for 7-10 days • Platelets become less functional as they age |
| Where are platelets found in the body? | -2/3rds of all platelets in the body are in circulation and the rest remain in the red pulp of the spleen - when animal is excited they release adrenalin which then contracts the spleen and the platelets are released into the blood stream |
| Platelet Morphology | • Shape: Discoid, oval, slightly elongated • Size: Variable • Romanowsky Stains : Central cluster of azurophilic granules; Pale blue background |
| What is the main function of platelets? | Hemostasis |
| What are other functions of platelets? | o Inflammation: May initiate or contribute to the inflammatory response; Thrombospondin – causes bacteria to adhere to platelet during inflammation and infection o Wound repair: Release vasoactive substances o Tissue repair |
| Hemostasis Process | Platelets are attracted & undergo shape change Platelet adhesion mediated by vWF TXA2 (thromboxane – released from damaged tissue) in combo with ADP recruit more platelets- form plug PF-3 activates the intrinsic coagulation system |
| Platelet Quantity | • Dog or cat – 200-400,000 per microliter of blood • ~10-20 platelets/oil immersion (1,000x) filed • Spontaneous bleeding may occur at <20,000 platelets per microliter |
| What is Thrombocytosis? | • Increased platelet count |
| What are the mechanisms for Thrombocytosis? | o Essential thrombocythemia – overproduction of platelets o Secondary (reactive) thrombocytosis – the body is reacting to something – platelets are being made for a reason o Physiological thrombocytosis – caused by a physiological response |
| What is Thrombocytopenia? | • Decreased platelet count (<100,000 per microliters of blood) |
| What are the mechanisms of Thrombocytopenia? | o Decreased production o Accelerated removal – body/disease is using them faster than the body is producing them o Abnormal distribution – many diseases can cause this o Combination of above |
| What is Thrombocytopathia? | • Decreased platelet function, not number |
| What are the mechanisms for Thrombocytopathia? | o Acquired – happened during the animal’s life that interfered with the platelets function o Congenital – animal born with disease that interferes with platelet function |
| What are the clinical Signs of Thrombocytopenia and Thrombocytopathia? | Bleeding from mucosal surfaces Melena (digested blood upper GI– black)/Hematochezia (fresh/frank blood lower GI) – blood in the stool Hematuria – blood in urine Epistaxis – nose bleed Cutaneous Ecchymoses – bruising Prolonged/excessive bleeding |
Created by:
jenn.messier11
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