production of formed elements

• Hematopoiesis: formation of all blood cells

  • occurs in red bone marrow
  • made of reticular connective tissue and blood sinusoids
  • found in axial skeletal, girdles, proximal epiphysis of humerus and femur
• erythropoiesis: Making RBCs

  • takes 15 days
• Leukopoiesis: production of WBCs are stimulated by two chemical messenger from red bone marrow and mature WBCs

  • interleukins are numbered
  • colony-stimulating factors named after what they stimulate
• leukocytes originate from hemocytoblast stem cells that branch off into:

  • lymphoid stem cell: produce lymphocytes
  • myeloid stem cell: produce all other elements
• production of leukocytes:

  1. myeloblasts: arise from myeloid stem cell
  2. promyelocytes: accumulate lysosomes
  3. myelocytes: accumulate granules
  4. Band cells: nuclei form curved arc
  5. mature granulocyte: nuclei are segmented before going into blood
• Production of Agranulocytes:

  • monocytes are derived from myeloid line

  monoblast ➡️ promonocyte ➡️ monocyte

  • share common precursor with neutrophils
  • live for several months