Carbon Dioxide Transport Quiz
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Questions and Answers

Where is carbonic anhydrase primarily found in the body?

  • In both plasma and red blood cells
  • In red blood cells only (correct)
  • In tissues and plasma
  • In plasma only

    • What is the primary form in which carbon dioxide is transported in the blood?

  • As dissolved gas in plasma
  • As carbamino compounds with hemoglobin and plasma proteins (correct)
  • As bicarbonate ions exclusively
  • As carbonic acid only

    • What percentage of carbonic acid formed in red blood cells dissociates to bicarbonate and hydrogen ions?

  • 100%
  • 50%
  • 99.9% (correct)
  • 75%

    • Why is the amount of carbon dioxide transported with plasma proteins less compared to hemoglobin?

    <p>The quantity of proteins in plasma is half that of hemoglobin</p> Signup and view all the answers

    How does carbon dioxide's combination with hemoglobin and plasma proteins facilitate its release?

    <p>The bond formed is reversible, allowing easy release in the alveoli</p> Signup and view all the answers

    What is the normal diffusion capacity of CO2 in ml/min/mmHg?

    <p>400</p> Signup and view all the answers

    Which of the following factors affects the diffusion rate through the pulmonary membrane most significantly?

    <p>Concentration gradient</p> Signup and view all the answers

    What is the approximate percentage of carbon dioxide transported in blood as bicarbonate?

    <p>63%</p> Signup and view all the answers

    What is the relationship between molecular weight and diffusion rate of gases?

    <p>Inversely proportional</p> Signup and view all the answers

    What is the ventilation-perfusion ratio at the apex of the lungs?

    <p>3.3</p> Signup and view all the answers

    How much carbon dioxide is transported in the blood as a dissolved form?

    <p>7%</p> Signup and view all the answers

    What is the thickness of the pulmonary membrane in microns?

    <p>0.6</p> Signup and view all the answers

    Which method accounts for the least transport of carbon dioxide in the blood?

    <p>As carbonic acid</p> Signup and view all the answers

    What percentage of oxygen is transported by hemoglobin in the blood?

    <p>97%</p> Signup and view all the answers

    What is the negligible amount of oxygen transported as a simple physical solution in plasma?

    <p>0.3 mL/100 mL of plasma</p> Signup and view all the answers

    During which condition does the transport of oxygen as a simple solution become particularly important?

    <p>During muscular exercise</p> Signup and view all the answers

    How is oxygen primarily transported in the blood?

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

    What role does the solubility of oxygen play in its transport in plasma?

    <p>It limits the amount transported as a solution.</p> Signup and view all the answers

    What is the primary site for the exchange of oxygen and carbon dioxide in the body?

    <p>In the alveoli of the lungs</p> Signup and view all the answers

    What process occurs at the alveolar-capillary interface?

    <p>Oxygen exchange</p> Signup and view all the answers

    What is a product of cellular respiration that is exchanged for oxygen in the tissues?

    <p>Carbon dioxide</p> Signup and view all the answers

    What physiological state is reached when hemoglobin can no longer carry any more oxygen?

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

    What is the primary reason the oxygen carrying capacity of blood is 19 mL% instead of the expected 20.1 mL% for 15 g% hemoglobin?

    <p>The hemoglobin is not fully saturated.</p> Signup and view all the answers

    How much oxygen can 1 gram of hemoglobin transport?

    <p>1.34 mL</p> Signup and view all the answers

    What form is the iron in heme part of hemoglobin during the oxygenation process?

    <p>Ferrous form</p> Signup and view all the answers

    What is the primary factor that determines the saturation of hemoglobin with oxygen?

    <p>Partial pressure of oxygen</p> Signup and view all the answers

    What percentage of oxygen in arterial blood is dissolved in the plasma?

    <p>0.3 mL/100 mL blood</p> Signup and view all the answers

    What is the effect of a higher partial pressure of oxygen on hemoglobin saturation?

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

    How is the percentage saturation of hemoglobin with oxygen calculated?

    <p>O2 content / O2 capacity X 100</p> Signup and view all the answers

    Study Notes

    Gas Transport

    • Oxygen and carbon dioxide are transported by the blood.
    • Oxygen is transported in two forms: as a simple physical solution in the plasma (a small amount), and in combination with hemoglobin (most of it).
    • The amount of oxygen transported as a simple physical solution in plasma is negligible, only about 3% of the total oxygen in the blood.
    • The majority (97%) of oxygen is transported bound to hemoglobin, forming oxyhemoglobin.
    • Hemoglobin's oxygen carrying capacity is 1.34 ml/g of hemoglobin.

    Oxygenation of Hemoglobin

    • Oxygen combines with hemoglobin only via a physical combination known as oxygenation, not oxidation.
    • Each hemoglobin molecule contains four iron atoms, and each iron atom combines with one oxygen molecule.
    • The iron remains in its ferrous form after combination. This is why the process is called oxygenation.

    Oxygen Carrying Capacity of Hemoglobin

    • Oxygen carrying capacity is the amount of oxygen transported by 1 gram of hemoglobin.
    • Normal hemoglobin content in blood is approximately 15 g%.
    • Assuming complete saturation with oxygen, this would equate to 20.1 mL% of oxygen in 100 mL of blood.
    • However, actual oxygen carrying capacity is 19 mL% due to hemoglobin not being fully saturated with oxygen, typically at about 95%.

    Oxygen Transport by Blood

    • Oxygen is primarily transported through chemical combination with hemoglobin (95-97%).
    • A small amount of oxygen is dissolved in plasma (3-5%).
    • Partial pressure of oxygen in arterial blood is ≈100 mmHg and in venous blood is ≈40 mmHg.

    Importance of Dissolved Oxygen

    • The partial pressure of oxygen in the blood helps determine the direction and rate of oxygen transport, and affects the amount of oxygen chemically combined with hemoglobin within red blood cells (RBC).

    Factors Affecting Gas Diffusion

    • Solubility: Diffusion capacity is directly proportional to the solubility of the gas. CO2 is significantly more soluble than O2 (20 times).
    • Pressure Gradient: The pressure difference between the alveoli and the tissues drives the diffusion of both oxygen and carbon dioxide.
    • Surface Area: The available surface area for gas exchange is important. Normal surface area for the lungs is approximately 70 m2.
    • Membrane Thickness: Diffusion rate is inversely proportional to membrane thickness. The thin alveolar membrane (0.6 microns) allows for efficient diffusion.
    • Concentration Gradient: Diffusion rate is proportional to the concentration gradient. O2 and CO2 gradients at lung and tissue capillaries are critical for efficient exchange.
    • Molecular Weight: Diffusion rate is inversely proportional to the molecular weight of the gas. CO2 diffuses slightly faster than O2 due to a slightly lower molecular weight.

    Ventilation-Perfusion Ratio (V/Q)

    • A balance between ventilation and blood flow in the lungs.
    • Normal ratio is V/Q = 0.8
    • This ratio varies throughout the lungs; it is higher at the apex of the lungs (more ventilation than perfusion) and lower at the base (more perfusion than ventilation).

    Transport of Carbon Dioxide

    • Carbon dioxide is transported from cells to alveoli by four methods.
    • Dissolved Form (7%): A small amount of CO2 dissolves directly into the plasma.
    • Carbonic Acid (Negligible): CO2 reacts with water to form carbonic acid, but the reaction is negligible.
    • Bicarbonate (63%): Most CO2 is converted to bicarbonate ions in red blood cells (RBCs).
    • Carbamino Compounds (30%): CO2 combines with hemoglobin to form carbaminohemoglobin.

    Chemical Factors and Dissolved Gases

    • Carbon dioxide binds loosely to proteins and hemoglobin in order that it can be easily released at the alveoli (where the partial pressure of carbon dioxide is low). The amount transported by combination with plasma proteins is lower than combined with hemoglobin, mostly due to the difference in quantities in the plasma vs. hemoglobin.

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    Description

    Test your knowledge on the transport of carbon dioxide in the body with this quiz. Explore key concepts such as the role of carbonic anhydrase, diffusion capacity, and the factors affecting the transport of CO2. Perfect for students studying respiratory physiology or related fields.

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