PSL301

• functions of blood

  • transport gasses, nutrients, hormones, and waste
  • regulate fluid composition
  • regulate blood loss by clotting
  • defense against pathogens and toxins
  • temperature regulation
• blood is made from plasma and formed elements
• hematocrit is the percentage of total blood volume occupied by RBC
• plasma is mostly water
• fibrinogen is needed for blood clotting
• general functions of plasma proteins

  • osmotic pressure
  • buffer pH (protons bind)
• erythrocytes = RBC
• leukocytes = WBC
• RBC are constantly produced and removed
• production of RBC = erythropoiesis
• erythropoietin are hormones made in the kidney that promotes RBC production
• erythropoiesis requires iron, vitamin B12, and folate in diet
• RBC produced in response to low oxygen levels
• bone marrow: more leukocytes are made
• hematopoiesis: production of a wide range of blood cells in the bone marrow
• removal of RBC

  taken up by macrophage and break down RBC
• DISEASE: jaundice (hyperbilirubinemia)

  causes:

  • high turnover of RBC
  • liver disease
  • bile duct obstruction

  symptoms:

  • yellow eyes
• causes of low erythrocyte production

  • lack of nutrients
  • destruction of stem cells via drugs (aplastic)
  • low erythropoietin via kidney failure (renal)
• causes of high erythrocyte removal

  hemolytic

  • defects in RBC protein (e.g. shape)
  • parasitic infections
  • drugs
  • autoimmune reactions

  hemorrhagic

  • excessive blood loss
• polycythemia: excess RBC / hematocrit too high
• causes of polycythemia

  • abnormal erythrocyte precursors
  • low oxygen delivery

  leads to blood clots and strokes
• functions of immune system

  • destroy pathogens
  • detect and destroy abnormal cells
  • remove cell debris
• viruses have a nucleic acid genome and require host cell to replicate
• two types of defence mechanisms and their chara & ex

  • innate immunity: rapid, non-specific. e.g. skin
  • acquired immunity: slow, specific. e.g. t-cells
• function of lymphatics

  • return excess tissue fluid to the blood
  • transport pathogens cells to lymph nodes
  • transport fat into blood
• spleen monitors blood
• monocytes differentiate into macrophages
• elements of the innate immune system

  • physical barriers
  • phagocytes
  • natural killer cells
  • antimicrobial proteins
  • inflammation
  • fever
• epithelium and the mucus layer is the first line of defense
• sequence of events for phagocytes

  1. chemotaxis: attracts WBC
  2. diapedesis: WBC enters tissue
  3. phagocytosis: engulfing bacteria
• phagocytes have cell surface receptors that recognize pathogens or antibodies
• opsonization: coating a pathogen to increase the likelihood of being taken up
• toll-like receptors: detects pathogens outside of the cells
• natural killer cells kill any cells that are infected or cancerous that do NOT have the MHC class I
• healthy cells have MHC class I, which natural killer cells recognize
• MHC class I inhibits cytokine production to destroy target cells
• interferon alpha and beta prevent viral replication
• interferon gamma activate macrophage and immune cells
• complement proteins causes cleavage of C3 that leads to inflammation, opsonization, formation of membrane attack complex
• inflammation: swelling, redness, heat, and pain