blood 1

• What is the main learning objective of Lecture 4 on blood?

  Understanding cellular regulation of blood components
• What does Erythropoietin regulate in blood cell production?

  Red blood cell production

  
• What environmental condition does Erythropoietin sense?

  Blood oxygen levels
• What are the major components of blood?

  Red blood cells, white blood cells, platelets
• What is the role of plasma in blood?

  Surrounds formed elements, contains proteins
• Where are red blood cells produced?

  Bone marrow
• What is the function of hemoglobin in red blood cells?

  Carries oxygen from lungs to tissues

  
• What happens to hemoglobin in the lungs?

  Combines with oxygen to form oxyhemoglobin
• What is the lifespan of red blood cells?

  About 4 months
• What shape do red blood cells have and why?

  Biconcave disc shape increases surface area

  
• Where are old red blood cells broken down?

  Liver, spleen, and bone marrow
• What are hematopoietic stem cells (HSCs)?

  Stem cells that produce blood cells

  
• What is the frequency of hematopoietic stem cells in the body?

  1 in 10,000
• What drives cellular differentiation in blood cell production?

  Cytokines and growth factors
• What initiates the production of red blood cells?

  Erythropoietin (Epo)

  
• What happens to CFU-E cells in the absence of Epo?

  They undergo apoptosis
• How does Epo affect CFU-E cells?

  Prevents apoptosis and triggers maturation
• What is the role of HIF-1α in Epo regulation?

  Activates Epo gene under low oxygen

  
• What is the structure of erythropoietin?

  Similar to GH and contains α helices
• What is the significance of reticulocytes in blood?

  They are immature red blood cells

  
• What percentage of erythrocytes do reticulocytes represent?

  0.6% to 2.9%
• What is the role of megakaryocytes in blood production?

  Produce platelets from their cytoplasm
• How large are megakaryocytes compared to red blood cells?

  10-15 times larger

  
• What is the function of platelets?

  Act at the site of vascular injury
• What are the functions of blood?

  • Transport oxygen and carbon dioxide
  • Regulate body temperature
  • Protect against pathogens
  • Maintain pH balance
• What are the steps in the production of red blood cells from HSCs?

  1. HSCs differentiate into erythroid progenitor cells
  2. Erythropoietin triggers proliferation and differentiation
  3. Cells undergo several divisions and maturation
  4. Mature red blood cells are released into circulation

  
• What are the components and roles of platelet surface molecules?

  • Glycoproteins: mediate adhesion and aggregation
  • Receptors: bind to ligands for activation
  • Lipids: involved in signaling pathways

  
• How does blood flow or shear rate impact platelets?

  • High shear rates activate platelets
  • Low shear rates promote aggregation
  • Shear stress influences clot formation

  
• What is the basis of ABO classification of blood types?

  • H antigen modification determines blood type
  • Anti-AB antibodies cause transfusion reactions
  • Blood type compatibility is crucial for transfusions

  
• Why is Rhesus factor important in pregnancy?

  • Determines Rh compatibility between mother and fetus
  • Rh incompatibility can lead to hemolytic disease
  • Monitoring is essential for maternal-fetal health

  
• What are the implications of EPO on sports performance?

  • Enhances oxygen delivery to muscles
  • Improves endurance and performance
  • Raises ethical concerns in sports
• What is the significance of the hematopoietic stem-cell niche in bone marrow?

  • Supports HSC maintenance and differentiation
  • Contains various cell types and signaling factors
  • Essential for blood cell production

  
• What is the role of reticulocytes in erythropoiesis?

  • Serve as markers for blood disorders
  • Indicate the rate of red blood cell production
  • Important in understanding various blood pathologies

  
• What is the process of platelet production from megakaryocytes?

  • Megakaryocytes undergo fragmentation
  • Platelets are pinched off from cytoplasm
  • Essential for hemostasis and wound healing
• What is the average diameter of a megakaryocyte?

  50-100 μm

  
• What is the primary function of megakaryocytes?

  Production of blood thrombocytes (platelets)
• How many bone marrow cells do platelets account for?

  1 out of 10,000
• Where are platelets held within megakaryocytes?

  Within internal membranes in the cytoplasm
• How much DNA can the nucleus of a megakaryocyte contain?

  Up to 64N DNA
• What shape do unactivated platelets have?

  Discoid (lens-shaped)