Oxy-hemoglobin dissociation curve

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Oxy-hemoglobin dissociation curve

• Interpretation
• Standard Reflects changes in Hb saturation with
  changes in PO2
• Variant Changes in O2 content with changes in PO2

2
Oxy-hemoglobin dissociation curve

• Interpretation
• Standard Reflects changes in Hb saturation with
  changes in PO2
• Variant Changes in O2 content with changes in PO2

• Dynamics

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Oxygen Transport
Bohr Effect
4
Oxy-hemoglobin dissociation curve

• Interpretation
• Standard Reflects changes in Hb saturation with
  changes in PO2
• Variant Changes in O2 content with changes in PO2

• Dynamics
• Changes in position affect the tendency to load
  or unload oxygen Bohr effect

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Volume rate transfer(oxygen)
Oxygen Transport

• Lung 0.5-1.0 microns
• Skeletal Muscle 80 microns
• Brain 40 microns
• distance (L) can usually be decreased by
  recruitment
• Myocardium 12 microns
• (approximately one capillary per muscle cell)

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At The Lung

• 70-80 of alveolar surface is covered by a single
  cell layer of red blood cells
• Maximal capacity is 200 ml blood
• Normal blood volume in the capillaries is 70 ml
• Alveolar-hemoglobin distance is 0.5 to 1.0 µm
• Capillaries cover several contiguous alveoli
• capillaries travel 600-800 µm before
  joining a venule
• In a normal resting individual, it takes
  750 msec for an RBC to traverse a gas
  exchange section

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Transit Time (msec)
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How about if transit time is decreased???
Transit Time (msec)
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• Oxygen uptake by blood (at the lung) is normally
  considered perfusion-limited
• The amount of oxygen taken up by blood at the
  lungs is normally limited only by the rate of
  blood flow
• Oxygen uptake by tissue (from blood) is normally
  considered diffusion-limited
• The amount of oxygen taken up by tissue from the
  blood is normallly limited by diffusion
  characteristics (partial pressure gradient,
  distance)

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Oxygen Transport
100
PO2
50
0
11
Oxygen Transport
Adequate
Critical
Inadequate
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Oxygen Transport
PO2
40
13
Oxygen Transport
PO2
0
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(No Transcript)
15
Oxygen Transport
No Bohr effect
Bohr effect
PO2
10
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Oxy-hemoglobin dissociation curve

• Interpretation
• Standard Reflects changes in Hb saturation with
  changes in PO2
• Variant Changes in O2 content with changes in PO2

• Dynamics
• Changes in position affect the tendency to load
  or unload oxygen Bohr effect
• Changes in shape usually reflect chemical
  alteration of the molecule
• Methemoglobin
• Thalessemias
• Carbon monoxide

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Oxygen Transport
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Hypoxia Inadequate tissue oxygenation

• At the lung hypoxic hypoxia
• At the blood
• Anemia (reduced RBCs or Hb)
• Carbon monoxide left-shifted O2-Hb curve and
  decreased carrying capacity
• Hypoxemia due to hemoglobin mutation
  (thalassemia)
• Perfusion-related (stagnant hypoxia)
• Tissue level
• Metabolic disorders
• Poisons
• Cyanide inhibits oxidative phosphorylation
• Dinitrophenol uncouples oxidative
  phosphorylation
• Carbon monoxide (cytochrome binding) prevents
  electron transfer to oxygen