human anatomy

• Cardiovascular system


  The system responsible for circulating blood throughout the body
• Blood


  • Composed of plasma and a variety of cells
  • Transports nutrients and wastes

  
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets

  
• Extracellular fluid


  Fluid that bathes the cells of the body, including blood and interstitial fluid
• Intracellular fluid


  Fluid contained within the cells of the body
• Blood plasma


  • Over 90% water
  • 7% plasma proteins
  • 2% other substances like electrolytes, nutrients, hormones, gases, waste products

  
• Red blood cells (erythrocytes)

  • Contain oxygen-carrying protein hemoglobin
  • Biconcave disk shape
  • No nucleus or organelles

  
• White blood cells (leukocytes)

  • Granular leukocytes: neutrophils, eosinophils, basophils
  • Agranular leukocytes: lymphocytes, monocytes

  
• Platelets


  Special cell fragments
• Hematocrit


  Percentage of blood occupied by cells

  
• Anemia


  Not enough red blood cells or not enough hemoglobin
• Polycythemia


  Too many red blood cells (over 65%)

  
• Hematopoiesis (or hemopoiesis)


  1. Process of blood cell formation

  2. Occurs in red bone marrow

  3. Stimulated by hematopoietic growth factors

  
• Pluripotent stem cells


  • 0.1% of red marrow cells
  • Replenish themselves as they differentiate into myeloid or lymphoid stem cells

  
• Myeloid stem cell line of development

  1. Progenitor cells develop into blast cells

  2. Blast cells develop into mature cell types
• Lymphoid stem cell line of development

  Pre-B cells & prothymocytes develop into B & T lymphocytes in lymphatic tissue
• Erythropoietin (EPO)


  Hormone produced by kidneys that increases red blood cell precursors
• Thrombopoietin (TPO)


  Hormone from liver that stimulates platelet formation
• Cytokines


  Local hormones of bone marrow that stimulate proliferation of other marrow cells
• Hemoglobin


  Globin protein with heme pigment that can reversibly bind oxygen
• Red blood cell life cycle

  • Live 120 days
  • Worn out cells removed by macrophages in spleen and liver

  
• Recycling of hemoglobin components


  1. Globin portion broken down into amino acids

  2. Heme portion split into iron and biliverdin
• Iron metabolism


  • 10-20% of dietary iron absorbed daily
  • Mainly used for erythropoiesis
  • Excess stored as ferritin and hemosiderin
• Erythropoiesis


  • Formation of red blood cells in red bone marrow
  • Stimulated by tissue hypoxia and erythropoietin

  
• Normal reticulocyte count is 0.5 to 1.5% of circulating red blood cells

  
• Erythropoiesis


  Production of red blood cells (RBCs)

  
• Erythrocyte formation (erythropoiesis)


  1. Occurs in adult red bone marrow

  2. Proerythroblast starts to produce hemoglobin

  3. Nucleus is ejected & a reticulocyte is formed

  4. Reticulocytes escape from bone marrow into the blood

  5. In 1-2 days, they eject the remaining organelles to become a mature RBC
• Tissue hypoxia


  Cells not getting enough oxygen
• Tissue hypoxia


  Increases RBC production
• RBC production falls below RBC destruction


  Occurs in anemia or circulatory problems
• Kidney response to hypoxia

  Release erythropoietin to speed up development of proerythroblasts into reticulocytes
• Normal reticulocyte count


  0.5 to 1.5% of the circulating RBCs

  
• Low reticulocyte count


  Indicates bone marrow problem, leukemia, nutritional deficiency or failure of red bone marrow to respond to erythropoietin stimulation
• High reticulocyte count


  Indicates recent blood loss or successful iron therapy
• Types of leukocytes (white blood cells or WBCs)

  • Granular (neutrophils, eosinophils, basophils)
  • Agranular (lymphocytes and monocytes)

  
• Blood


  The liquid that circulates in the body's heart, arteries, veins, and capillaries, carrying oxygen, nutrients, and waste products.
• Major histocompatibility antigens (MHC)


  Surface proteins on leukocytes, unique for each person (except for identical siblings), can be used to identify a tissue

  
• Plasma


  The liquid portion of blood, made up of water, proteins, electrolytes, hormones, and other substances.
• Leukocytosis


  High white blood cell count, caused by microbes, strenuous exercise, anesthesia or surgery

  
• Red blood cells (RBCs)

  Cells responsible for carrying oxygen from the lungs to the rest of the body. They contain a protein called hemoglobin, which binds to oxygen and facilitates its transport.