Oxygen Transport and Dissociation Curve
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Questions and Answers

What is the maximum amount of oxygen that 100 ml of arterial blood can transport?

  • 20.1 ml (correct)
  • 15 ml
  • 50 ml
  • 25 ml

    • What percentage of oxygen-binding sites on hemoglobin are occupied by oxygen, known as O2 saturation?

  • Varies based on conditions (correct)
  • 100%
  • 75%
  • 50%

    • Which factor contributes to the sigmoid shape of the O2 dissociation curve?

  • Non-cooperative binding of oxygen
  • Increase in blood pH
  • Presence of intermediate compounds (correct)
  • High temperature

    • How much oxygen does arterial blood lose to the tissues per 100 ml?

    <p>5 ml</p> Signup and view all the answers

    What is the primary function of hemoglobin in the respiratory system?

    <p>To load O2 in the lungs and unload it in the tissues</p> Signup and view all the answers

    At what O2 tension does hemoglobin reach approximately 98% saturation?

    <p>100 mmHg</p> Signup and view all the answers

    What effect does the binding of the first oxygen molecule have on hemoglobin's affinity for additional oxygen molecules?

    <p>Increases the affinity</p> Signup and view all the answers

    What is the coefficient of oxygen utilization when arterial blood content is 20 ml and venous blood content is 15 ml?

    <p>50%</p> Signup and view all the answers

    How is the majority of oxygen transported in the blood?

    <p>Chemical combination with hemoglobin</p> Signup and view all the answers

    What is the significance of Henry's law in oxygen transport?

    <p>It explains that oxygen dissolved in blood is proportional to its partial pressure.</p> Signup and view all the answers

    What is the approximate amount of oxygen dissolved in one liter of arterial blood at 37°C per mmHg?

    <p>3 mL</p> Signup and view all the answers

    What is the oxygen content in the blood calculated from?

    <p>1.34 mL O2/dL blood × [Hemoglobin]</p> Signup and view all the answers

    Which statement about the oxygen dissociation curve is correct?

    <p>It reflects the unloading of oxygen from hemoglobin in tissues.</p> Signup and view all the answers

    What does the term 'O2 saturation' refer to?

    <p>The percentage of hemoglobin binding sites occupied by oxygen.</p> Signup and view all the answers

    What is a major pathway for O2 transport across capillary walls?

    <p>Dissolved oxygen determined by partial pressure</p> Signup and view all the answers

    Which factor can cause a shift in the O2 dissociation curve to the right?

    <p>Lower pH (increased acidity)</p> Signup and view all the answers

    What happens to hemoglobin (Hb) saturation when the O2 tension decreases from 100 mmHg to 60 mmHg?

    <p>It decreases from 98% to 90%.</p> Signup and view all the answers

    What is a primary physiological significance of the flat part of the O2 dissociation curve?

    <p>It allows for a large unloading of O2 even with small falls in blood PO2.</p> Signup and view all the answers

    During muscular exercise, if the PO2 drops to between 15-30 mmHg, what is the approximate Hb saturation?

    <p>35%</p> Signup and view all the answers

    Which physiological factor shifts the O2 dissociation curve to the right?

    <p>Increased temperature.</p> Signup and view all the answers

    What effect does 2,3 Diphosphoglycerate (2,3 DPG) have on hemoglobin's affinity for O2?

    <p>It reduces the affinity for O2.</p> Signup and view all the answers

    What role does the Bohr effect play in O2 delivery to tissues?

    <p>It increases O2 delivery in the presence of high CO2 and H+.</p> Signup and view all the answers

    What is the result of decreased blood pH on the O2 dissociation curve?

    <p>It shifts the curve to the right.</p> Signup and view all the answers

    What happens to the saturation of hemoglobin at an O2 tension of 40 mmHg?

    <p>It is 75%.</p> Signup and view all the answers

    What causes histotoxic hypoxia?

    <p>Inactivation of metabolic enzymes</p> Signup and view all the answers

    Cyanosis indicates what condition?

    <p>Excessive deoxygenated hemoglobin</p> Signup and view all the answers

    What is a primary characteristic of central cyanosis?

    <p>Caused by reduced O2 saturation</p> Signup and view all the answers

    What causes peripheral cyanosis?

    <p>Increased oxygen extraction from blood</p> Signup and view all the answers

    Which condition does NOT result in cyanosis?

    <p>Severe cold affecting hemoglobin uptake</p> Signup and view all the answers

    What effect does an increase in PCO2 have on the oxygen-hemoglobin dissociation curve?

    <p>Shifts the curve to the right</p> Signup and view all the answers

    Why does fetal hemoglobin (HbF) have a higher affinity for oxygen compared to adult hemoglobin?

    <p>It allows better oxygen uptake in the placenta</p> Signup and view all the answers

    What is a characteristic feature of myoglobin compared to hemoglobin?

    <p>It does not demonstrate cooperativity in O2 binding</p> Signup and view all the answers

    What is the impact of carbon monoxide on hemoglobin?

    <p>Decreases the binding of oxygen to hemoglobin</p> Signup and view all the answers

    During muscular exercise, which factor contributes to the right shift of the oxygen-hemoglobin dissociation curve?

    <p>Increased production of acids</p> Signup and view all the answers

    What happens to the myoglobin oxygen dissociation curve under low oxygen tension during exercise?

    <p>It descends steeply after reaching a certain level</p> Signup and view all the answers

    How does an increase in temperature affect the oxygen-hemoglobin dissociation curve?

    <p>It shifts the curve to the right</p> Signup and view all the answers

    What is the cause of carbon monoxide poisoning?

    <p>It binds to hemoglobin with high affinity</p> Signup and view all the answers

    What effect does carbon monoxide (CO) have on hemoglobin (Hb) concentration?

    <p>Prevents Hb from binding with O2</p> Signup and view all the answers

    What characterizes hypoxic hypoxia?

    <p>Decreased arterial PO2 and Hb saturation</p> Signup and view all the answers

    Which of the following is a cause of anaemic hypoxia?

    <p>Carbon monoxide poisoning</p> Signup and view all the answers

    What happens to the oxygen dissociation curve of remaining oxyhemoglobin when carbon monoxide is present?

    <p>Shifts to the left</p> Signup and view all the answers

    Which of the following types of hypoxia is characterized by normal Pa O2 and normal saturation of hemoglobin?

    <p>Stagnant hypoxia</p> Signup and view all the answers

    Which condition can lead to hypoxic hypoxia due to impaired oxygen diffusion?

    <p>Emphysema</p> Signup and view all the answers

    What would result in stagnant hypoxia?

    <p>Normal Pa O2 and normal hemoglobin saturation</p> Signup and view all the answers

    In anaemic hypoxia, which parameter remains normal despite reduced oxygen content?

    <p>Pa O2</p> Signup and view all the answers

    Study Notes

    Oxygen Transport

    • Oxygen is carried by the blood, bound to hemoglobin (Hb) or dissolved in fluids.
    • The amount of dissolved oxygen is proportional to its partial pressure (Henry's Law).
    • At 37°C, 3 mL of oxygen is dissolved per liter of arterial blood per mmHg.
    • Dissolved oxygen isn't sufficient for the body's needs, requiring hemoglobin for transport.
    • Hemoglobin carries oxygen via chemical combination.
    • Each hemoglobin molecule has four iron atoms, each binding one oxygen molecule.
    • Oxygen content in arterial blood is calculated as 1.34 mL O2/dL blood × [Hemoglobin].
    • 100 mL of blood containing 15 g of Hb can transport 20 mL of O2.
    • Oxygen saturation is the percentage of oxygen-binding sites on hemoglobin occupied by oxygen.
    • Oxygen utilization is the amount of oxygen lost from 100 mL of arterial blood to the tissues (50 mL/liter).

    Oxygen Dissociation Curve

    • The curve shows the relationship between oxygen tension (PO2) and hemoglobin saturation (% HbO2).
    • It's sigmoidal (S-shaped), with a steep slope between 10 and 60 mmHg PO2 and a relatively flat portion between 60 and 100 mmHg PO2.
    • The sigmoid shape is due to cooperative binding of oxygen to hemoglobin.
    • The binding of one oxygen molecule increases the affinity of the next for subsequent hemoglobin binding.
    • Hemoglobin loads oxygen in the lungs (high PO2) and unloads it in the tissues (low PO2).

    Factors Affecting the O2 Dissociation Curve

    • Factors shifting the curve to the right (decreased affinity of Hb for O2) include:

      • Increased temperature
      • Increased carbon dioxide concentration
      • Decreased pH (increased H+ concentration)
      • Increased 2,3-diphosphoglycerate (2,3-DPG) concentration.

    • Factors shifting the curve to the left (increased affinity of Hb for O2) include:

      • Decreased temperature
      • Decreased carbon dioxide concentration
      • Increased pH (decreased H+ concentration)
      • Decreased 2,3-DPG concentration

    Bohr Effect

    • The Bohr effect describes how changes in CO2 and H+ concentration affect oxygen delivery to tissues.
    • Increased CO2 and H+ shift the curve to the right, increasing oxygen unloading in tissues.

    Types of Hypoxia

    • Hypoxic hypoxia: decreased PO2 of arterial blood
    • Anemic hypoxia: decreased amount of functional hemoglobin
    • Stagnant hypoxia: reduced blood flow to tissues
    • Histotoxic hypoxia: metabolic poisons block the utilization of oxygen by tissues

    Carbon Monoxide (CO) Poisoning

    • CO has a much higher affinity for hemoglobin than oxygen.
    • CO binding prevents oxygen from binding to hemoglobin.
    • This shifts the oxygen-hemoglobin dissociation curve to the left, reducing oxygen unloading to tissues.

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    Description

    This quiz tests your understanding of how oxygen is transported in the blood via hemoglobin and its relation to the oxygen dissociation curve. Key concepts include the roles of hemoglobin and dissolved oxygen, as well as the physiological factors affecting oxygen saturation. Test your knowledge on vital statistics and principles governing oxygen transport in the human body.

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