Blood homeostasis

• Function of blood:

  Distribution

  • oxygen and nutrients
  • carbon dioxide and waste

  Regulation

  • body temperature
  • pH
  • fluid volume

  Protection

  • against haemorrhage (fibrinogen)
  • against infection (leukocytes/white blood cells(
• Formed elements

  • erythrocytes
  • leukocyts
  • thrombocytes
• Blood with anticoagulant:

  • plasma (55%)
  • buffy coat - composed of leukocytes and platelets
  • red blood cells (45%)
• blood without anticoagulant:

  • Serum (fibrinogen depleted)
  • Buffy coat / layer
  • clot (red blood cells + fibrin)
• Components of plasma

  • Proteins (7%)
  • water (91.5%)
  • other solutes (1.5%)
• What proteins are found in plasma

  • Albumins (54%)
  • globulins (38%)
  • fibrinogen (7%)
  • all other (1%)
• What are some other solutes found in plasma

  • electrolytes
  • nutrients
  • gases
  • regulatory substances
  • vitamins
  • waste products
• Formed element of the blood:

  • platelets
  • white blood cells
  • red blood cells
• white blood cells:

  • neutrophils (60-70%)
  • lymphocytes (20-25%)
  • monocytes (3-8%)
  • eosinophils (2-4%)
  • basophils (0.5-1%)
• Haemopoiesis:

  1. pluripotent stem cell in bone marrow
  2. lymphoid or myeloid stem cells
  3. become myloblast or lymphoblasts
  4. Lymphoid become b or t cells
  5. myeloid become: erythrocytes, platelets, monocytes, neutrophils, eosinophils, basophils
• Stains

  • eosin
  • methylene blue
  • wrights stain
• eosin stain

  • stains basic/alkali components red (proteins)
• wright stain

  eosin and methylene blue
• Methylene blue

  • stains acidic components blue (DNA)
• Basophil:

  • bilobed nucleus
  • blue granules (histamines)
• Eosinophils:

  • bilobed nucleus
  • red granules (basic proteins)
• neutrophils:

  • multi-lobed nucleus
  • few granules
• Monocytes

  • horse-shoe shaped nucleus
  • large cells
• Platelets:

  • not cells
  • no nucleus
  • small
• Erythrocyte formation:

  • pluripotent stem cell
  • myeloid stem cell
  • CFU-E
  • proerythroblast
  • nucleus ejects to form reticulocyte
  • red blood cell
• Platelets formation:

  • pluripotent stem cell
  • myeloid stem cell
  • CFU-Meg
  • megakaryoblast
  • megakaryocyte
  • platelet
• Erythrocyte:

  • formation (eyrthropoiesis) occurs in bone marrow, stimulated by erythropoietin (produced by kidney)
  • anuclear
  • biconcave shape
  • haemoglobin (33% of weight)
  • Oxygen transport / CO2 removal
  • make 2 million per second
  • lasts 120 days
• Granulocytes:

  • Neutrophil
  • eosinophil
  • basophil
• Neutrophil:

  • phagocytes: move to site of infection
• Eosinophils:

  • allergic response and parasitic invasion
• Basophils

  • allergic, inflammatory response and parasitic invasion
• Agranulocytes:

  lymphocytes

  monocytes
• monocytes

  • differentiate into macrophages
  • phagocytes can recruit other elements of immune system
• Platelets:

  • contain clotting/coagulation factors
  • cytoplasm of megakaryocytes pinched off to produce platelets (2-3 micrometers diameter)
• Haemostasis:

  Stops bleeding by:

  • vascular spasm
  • platelet plug
  • blood clot formation fibrinogen (soluble) converted to fibrin (insoluble threads)
• Platelet plug formation:

  • connective tissue (collagen) traps a layer of platelets
• Blood clot formation: platelets stick together to form a plug, which stops the blood flowing held together by fibrin threads
• Tissue fluid fomation:

  • 2 forces involved hydrostatic pressure (pushing) and osmotic pressure (pulling)
  • net filtration pressure = net hydrostatic pressure - net osmotic pressure
• components of tissue fluid:

  Arterial end

  • water
  • glucose
  • amino acids
  • mineral salts
  • oxygen

  Venous end

  • Carbon dioxide
  • other waste
• Filtration occurs where?

  Arterial end
• Lymph

  • lymph accounts for 3 litres of fluid not reabsorbed
  • lymphatic vessels transport lymph frlm tissue spaces to veins
  • lymph drains into the circulatory system via lymphatic ducts locates in veins near the heart