L8 - Blood

• What are the three components of the cardiovascular system?

  Blood, heart, and blood vessels
• What substances are exchanged between blood and interstitial fluid?

  Oxygen, nutrients, and metabolic wastes
• What are the main functions of blood?

  • Transportation of oxygen, nutrients, and hormones
  • Regulation of body temperature, pH, and fluid balance
  • Protection against blood loss and infection
• What is the pH range of blood?

  7.35 to 7.45
• What percentage of body mass does blood constitute?

  About 8%
• What are the components of blood composition?

  • Blood plasma (55%)
  • Red blood cells (45%)
  • Buffy coat with white blood cells and platelets (<1%)
• What is the primary component of blood plasma?

  About 90% water
• What are the main solutes found in blood plasma?

  Nutrients, ions, gases, hormones, and wastes
• What are the formed elements of blood?

  • Leukocytes (white blood cells)
  • Erythrocytes (red blood cells)
  • Platelets (cell fragments)
• What is hematopoiesis?

  Blood cell formation in red bone marrow
• What is the role of hemocytoblasts?

  They are stem cells for blood cell formation
• What are the steps in erythropoiesis?

  1. Hemocytoblast to myeloid stem cell
  2. Proerythroblast to reticulocyte
  3. Reticulocyte matures into erythrocyte
• What is the main function of erythrocytes?

  Gas transport
• What is hemoglobin primarily composed of?

  Four globin proteins with heme rings
• How does hemoglobin behave in the lungs?

  It binds O2 and becomes bright red
• What enzyme do red blood cells contain?

  Carbonic anhydrase
• What is the process of erythropoiesis regulated by?

  • Erythropoietin (EPO) hormone
  • Triggered by hypoxia
  • Enhanced by testosterone
• What is the lifespan of red blood cells?

  About 120 days
• What happens to red blood cells after they die?

  They are destroyed by macrophages
• What are the normal hematocrit ranges for adults?

  • Adult females: 41%
  • Adult males: 47%
• What is polycythemia?

  High hematocrit and high RBC number
• What causes anemia?

  Blood loss, low RBC production, or Hb abnormalities
• What is sickle-cell anemia caused by?

  One amino acid change in β-globin chain
• Why does the sickle-cell trait persist in certain populations?

  It provides better malaria survival chances
• What is the significance of normal erythrocytes?

  • They have a normal hemoglobin amino acid sequence
  • They efficiently transport oxygen
• What percentage of females have a higher hematocrit than males?

  41%
• What is polycythemia characterized by?

  High hematocrit and high RBC number
• What causes polycythemia?

  Low blood O2 or disease
• What effect does polycythemia have on blood viscosity?

  Increases blood viscosity due to increased RBC
• What is anemia characterized by?

  Low hematocrit and low RBC number
• What are some causes of anemia?

  Blood loss, low RBC production, Hb abnormalities
• What happens to hemoglobin under low O2 conditions in sickle-cell anemia?

  Hb becomes spiky and sharp
• How does the shape of sickled erythrocytes affect their function?

  Interferes with O2 delivery
• In which population is sickle-cell anemia most prominent?

  People from the malaria belt of Africa
• Why does the sickle-cell trait persist in some populations?

  Provides better survival chance against malaria
• What is the ratio of African-American newborns affected by sickle-cell anemia?

  1:500
• What are leukocytes commonly known as?

  White blood cells
• What is unique about leukocytes compared to other blood components?

  Only formed element that is a complete cell
• What percentage of whole blood do leukocytes constitute?

  Less than 1%
• What is the primary role of leukocytes?

  Critical to disease defense