Hemoglobin Flashcards
Hemoglobinopathies
Sickle Cell Disease, Thalassemia, Methemoglobinemias
Total Blood Volume in human body
5 Liters
Flow of oxygen in the body
O2 - Bronchi - Lungs - Hb - (Mb) - Mitochondria - H2O
Causes of Hypoxia:
Pre-pulmonary (bronchitis) Post-pulmonary (CO, anemia)
Total oxygen content =
O2 on Hb (SaO2) + dissolved O2(PO2)
The normal lifetime of a RBC is
120 days
Hemoglobin hues:
Red - Healthy and robust
Pale - Anemic (e.g., neonatal, aplastic, hemolytic)
Blue - Hypoxemia - Cyanosis
Yellow - Jaundiced (Bilirubin increased)
Cherry Red - CO poisoning
Brown/blue - Methemoglobinemia (Chocolate cyanosis)
Reguired for oxygen binding
Both globin and heme
Apoprotein
Globin alone
Holoprotein
Heme (prosthetic group-tightly bound organic molecule) + the globin chain.
“OXY Hb” (Fe2+)
Arterial form
Deoxy Hb (Fe2+)
Venous form
Heme/Hb synthesis
occurs in differentiating bone marrow cells
Hypoxia Inducible Factor (HIF):
Erythropoiesis, angiogenesis, energy metabolism, glycolysis, cell survival
Heme/Hb Degradation
Aged RBC - Taken up by Spleen, Phagocytes (RES System) - Bilirubin Diglucouronide (Antioxidant) - Excretion in bile
Heme composed of
protoporphyrin IX ring and Fe++ ion
Fe++ ion coordinated by
4 nitrogen atoms of ring, a proximal histidine residue and an O2 molecule (in oxy-hemoglobin); 6th position empty in deoxy Hb
Distal ______ H-bonds to the bound O2
histidine
Diminished production of alpha or beta chains. Leads to unstable forms of Hb that are not fully functional ( no cooperativity or allosterism) and have low solubility
Thalassemias
O2 binding changes position of
Fe++ atom
Hemoglobin binds O2 _______
cooperatively
What does 2,3-Bisphosphoglycerate do?
enhances the efficiency of oxygen delivery