BIOL 2420 Lecture Notes - Lecture 4: Fetal Hemoglobin, Red Blood Cell, Hemoglobin A
26 Apr 2018
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Unit 6 – Lecture 4
Several Factors Affect Oxygen-Hb Binding
- Any factor that changes the conformation of the hemoglobin protein can affect its ability to bind
oxygen
o Physiological changes in plasma pH, temperature, PCO2 all alter the binding affinity of
hemoglobin
▪ Binding affinity are reflected in the shape of the HbO2 saturation curve
- Decreased pH, increased temperature, increased PCO2 decrease the affinity of hemoglobin for
oxygen and shift the oxygen-hemoglobin saturation curve to the right
- Increased pH, decreased temperature, decreased PCO2 increase the affinity of hemoglobin for
oxygen and shift the oxygen-hemoglobin saturation curve to the left
- When the curve shifts in either direction, the changes are much more pronounced in the steep
part of the curve
o Oxygen binding at the lungs is not greatly affected but oxygen delivery at the tissues is
significantly altered
- When does the body undergo shifts in blood pH?
o Maximal exertion that pushes cells into anaerobic metabolism
▪ Exercising muscle fibers releases H+ into the cytoplasm and extracellular fluid
▪ As H+ concentrations increase, pH falls, the affinity of hemoglobin for oxygen
decreases and the HbO2 saturation curve shifts to the right
▪ More oxygen is released at the tissues as the blood becomes more acidic (pH
decreases)
• Bohr effect: a shift in the hemoglobin saturation curve from a change in
pH
2,3-bisphosphoglycerate – an additional factor that affects oxygen-hemoglobin binding
- Compound made from an intermediate of the glycolysis pathway
- Chronic hypoxia
o Triggers an increase in 2,3-BPG production in red blood cells
- Increased levels of 2,3-BPG lower the binding affinity of hemoglobin and shift the HbO2
saturation curve to the right
- Ascent to high altitude and anemia are two situations that increase 2,3-BPG production
Chages i heogloi’s struture
- Change its oxygen-binding affinity
- Example: fetal hemoglobin (HbF)
o Has 2 gamma protein chains in place of the two beta chains found in adult hemoglobin
o Presence of gamma chains enhances the ability of fetal hemoglobin to bind oxygen in
the low-oxygen environment of the placenta
o Altered binding affinity is reflected by the different shape of the fetal HbO2 saturation
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Document Summary
Decreased ph, increased temperature, increased pco2 decrease the affinity of hemoglobin for oxygen and shift the oxygen-hemoglobin saturation curve to the right. Increased ph, decreased temperature, decreased pco2 increase the affinity of hemoglobin for oxygen and shift the oxygen-hemoglobin saturation curve to the left. 2,3-bisphosphoglycerate an additional factor that affects oxygen-hemoglobin binding. Compound made from an intermediate of the glycolysis pathway. Chronic hypoxia: triggers an increase in 2,3-bpg production in red blood cells. Increased levels of 2,3-bpg lower the binding affinity of hemoglobin and shift the hbo2 saturation curve to the right. Ascent to high altitude and anemia are two situations that increase 2,3-bpg production. Gas transport in the blood includes carbon dioxide removal from the cells as well as oxygen delivery to cells. Carbon dioxide is a by product of cellular respiration and is potentially toxic if not excreted (removed from the body) Is available to act as a buffer for metabolic acids sta(cid:271)ilizes the (cid:271)od(cid:455)"s ph.
