RESPIRATORY SYSTEM

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RESPIRATORY SYSTEM
Mark Welliver CRNA MS
Mark Welliver Slide 2006
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Outline

• I. Hemoglobin
• II. Oxygen carrying
• III. Carbon Dioxide carrying
• IV. Diffusion
• Haldane effect
• Bohr effect
• V. Arterial Blood Gas Analysis

Mark Welliver Slide 2006
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Oxygen
Total body stores of oxygen 1500
ml lungs bound to hemoglobin dissolved Oxygen
Tension Tissue Hypoxia inadequate arterial O2
tension 1) hypoxemic-hypoxia-hypoxia d/t
hypoxemia 2) anemic hypoxia -inadequate O2
carrying capacity 3) circulatory hypoxia
-stagnant hypoxia poor capillary 4)
histotoxic hypoxia -failure of O2 utiliz.at
cellular level Basal Metabolic Rate O2- 250
ml/minute, producing 80
ml CO2/100ml Respiratory Quotient (RQ) 0.8 (200
ml CO2/250 ml O2 used
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MM

• Oxygen ContentCaO2 dissolved O2
• CaO21.34ml/dl x Hgb x SaO2
• Dissolved0.003ml O2 x PaO2

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O2 Affinity Alterations

• Carboxyhemoglobin- Carbon Monoxide 250x greater
  affinity for Hgb than O2. Forms covalent bounds
  with ferrous ion
• Methemoglobin (Met Hb)-ferrous ion (Fe)
  oxidized to Ferric state (Fe). Hgb turns
  brown. Unable to bind reversibly to hgb.
• Fetal Hgb (HbF)- Differs from Adult Hgb (HbA). 2
  gamma polypeptide chains replace 2 beta
  polypeptide chains. O2 affinity increased. Also
  more easily oxidized to methemoglobin

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Hemoglobin

• Hemoglobin- Main component of Red Blood Cells
  (RBC)
• Single RBC contains 280 million molecules Hgb
• Each Hgb molecule
• weight 64,5000
• Contains 10,000 atoms of H, C, N, O, S
• Contains 4 iron atoms (Fe) in the ferrous form
  Fe

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Hemoglobin Molecule
iron
heme
globin
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Hemoglobin (heme)

• Porphyrin- 4 pyrrole rings cyclically linked by
  methylene bridges
• Porphyrins capable of forming covalent bonds
  w/metals.
• Ferrous ion (Fe) has 6 valence bonds available,
  binds to 4 nitrogens on a porphyrin ring forming
  heme

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Heme
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Pyrole
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Porphyrin
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Heme
methylene bridge
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Ferrous ion Fe
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Poly peptide chain
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Hemoglobin
O2
CO2
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Hemoglobin (globin)

• Amino Acids- 4 specific amino acid chains
  (polypeptide chains), 2 alpha, 2 beta combined
  form protein globin.
• Globin- Contains imidazole nitrogen groups form
  covalent bonds w/metals

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O2 carried by Hemoglobin
O2
CO2
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Carbon Dioxide (CO2)

• Carried in blood Three ways
• Dissolved
• Bicarbonate (combined with water)
• Carbamino compounds (combined with hemoglobin)

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Carbon Dioxide Carriage in Blood
(HCO3-)
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CO2 Transport Mechanisms

• Dissolved CO2- minimal
• Carbamino CO2 compounds- Bound to amino acids
  hemoglobin.
• Bicarbonate ion- Carbonic anhydrase enzyme in RBC
  and renal tubular cells speeds CO2 hydration to
  carbonic acid
• CO2 H2O ca H2CO3 H HCO3-

Carbonic acid
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CO2 Transport- Bicarb

• Tissue CO2 enters blood, small amt. remains in
  physical solution (plasma), Rest diffuses into
  RBC, portion binds with Hgb(carbamino-O2), 65
  CO2 quickly transformed to hydrogen(H) and
  bicarb(HCO3-), the hydrogen ions bind to Hgb.
  Bicarb then diffuses into plasma (gradient),
  Chloride ions(Cl-) migrate into RBC to maintain
  electroneutrality (chloride shift)

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Bohr Effect (attributed at tissue level)

• CO2 addition to blood enhances O2 release from
  Hgb. It is an adaptation in animals to release
  oxygen in the oxygen starved tissues of
  capillaries where respiratory carbon dioxide
  lowers blood pH. When blood pH decreases, the
  ability of hemoglobin to bind to oxygen
  decreases. Hemoglobin binds to oxygen in the
  oxygen-rich atmosphere of the lungs, and releases
  it in the oxygen-poor environment of the tissues.
  

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Haldane Effect (attributed at lungs)

• O2 addition to blood enhances release of CO2 from
  Hgb. O2 makes Hgb a stronger acid (less capable
  of binding with H). Bicarb and carbamino
  mechanisms are reversed, CO2 reformed and
  diffused into alveoli, ventilated off

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Mark Welliver Slide 2006
At the lung
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?Venous side CO2 moves into plasma RBC.
?Hamburg effect (chloride shift) maintains
neutrality. ? Deoxygenated Hb 3.5 x gt
affinity for CO2
Venous capillary plasma

Red Blood Cell
?

• CO2 H2O HCO3- H

Hb
HCO3-
?
?
Cl-
HbH
Cl-
Blood already deoxygenated and on its return to
lungs
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?pulmonary side HCO3 moves into RBC converted to
CO2. ?Hamburg effect (chloride shift)
maintains neutrality. ? Oxygen diffuses
across pulmonary membranes bind w/hb
pulmonary capillary Plasma
Red Blood Cell

Alveoli

• CO2 H2O HCO3- H

?
HCO3-
?
Cl-
Cl-
?
HbO2HbO2
O2
Blood already deoxygenated and on its return to
lungs
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Arterial Blood Gas Analysis

• See tutorial ppt.
• Must know

Mark Welliver Slide 2006