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Thrombocytes (Platelets) & Plasma

Thrombocytes (Platelets) & Plasma. Structure. Fragments of giant cells (megakaryocytes) (each produces b/t 5-10,000 platelets) Enter circulation – live for approx. 1 wk.; destroyed by spleen & liver Disk-shaped, w/o nucleus ½ the size of an RBC. Function. Normal platelet count –

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Thrombocytes (Platelets) & Plasma

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  1. Thrombocytes(Platelets)&Plasma

  2. Structure • Fragments of giant cells (megakaryocytes) (each produces b/t 5-10,000 platelets) • Enter circulation – live for approx. 1 wk.; destroyed by spleen & liver • Disk-shaped, w/o nucleus • ½ the size of an RBC

  3. Function • Normal platelet count – 130,000-360,000/mm³ • Stem blood flow (hemo- stasis) 2 ways: 1. 2.

  4. Platelet Plug Formation 1. B.V.damaged 2. Some blood escapes 3. Platelets adhere to each other & rough surfaces 4. When platelets come in contact w/collagen from connective tissue, they develop spiny projections; helps them adhere 5. Eventually platelet plug is formed & bleeding stops

  5. Clotting Process - Coagulation • Cascade effect - • Extrinsic clotting – occurs when b.v. are damaged; platelets 1st release serotonin

  6. Blood Clots • Thrombus – • Embolus – blood clot or fragment of one that dislodges & travels to major organ

  7. Plasma • Clear, straw-colored fluid; matrix of blood • 92% water • Functions: 1. 2. maintain fluid balance 3.

  8. Contents of Plasma • Contains 3 plasma proteins (all produced in the liver): • Albumin – accounts for 60% of all plasma proteins - maintains osmotic pressure (keeps concentration of H2O & solutes in plasma stable - example – a decrease in albumin causes cells to lose H2O; it collects in interstitial spaces (b/t cells) & causes edema

  9. Plasma Proteins • Globulins – • Fibrinogen – Accounts for 4% of all plasma proteins - responsible for blood clotting

  10. Other Substances Plasma also contains: • nonprotein nitrogenous substances – • electrolytes – release ions when dissolved in H2O; maintain osmotic pressure & pH; include Na, K, Cl, Ca Mg, bicarbonate, PO4 & SO4 ions

  11. Blood Types • Antigen – protein on surface of RBC’s • Determines blood type • Possible antigens – A or B • Antibody – • Possible antibodies – A or B

  12. Human Blood Types

  13. Intrinsic Clotting (Agglutination) • Occurs when antigen comes in contact with foreign antibody (example – b.t. A receiving a transfusion of b.t. B) • Effects – • Symptoms – anxiety, difficulty breathing, chest pain, pain in neck & lumbar area

  14. Rh Blood Group • 85% of humans have an additional protein on their RBCs; called the Rh factor • Named after the species of monkey it was discovered in (Rhesus) • Remaining 15% of humans don’t have this protein • Rh- individuals cannot receive Rh+ blood

  15. Erythroblastosis Fetalis

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