23.7 Gas Transport
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Questions and Answers

What is the primary substance within an erythrocyte?

  • Mitochondria
  • Organelles
  • Plasma membrane
  • Hemoglobin (correct)

    • What is the estimated number of erythrocytes in the human body?

  • Over 20 trillion (correct)
  • 15 trillion
  • 2 trillion
  • 10 trillion

    • Why is most oxygen transported on hemoglobin rather than dissolved in plasma?

  • Hemoglobin is more efficient at transporting oxygen
  • Oxygen is more soluble in hemoglobin than in plasma
  • Plasma has a lower oxygen carrying capacity
  • Hemoglobin has a higher oxygen carrying capacity (correct)

    • Where does carbon dioxide diffuse into from the blood in the pulmonary capillaries?

    <p>The alveoli</p> Signup and view all the answers

    How is carbon dioxide transported from systemic cells to the lungs?

    <p>Through the systemic circulation to the right side of the heart, then to the pulmonary circulation</p> Signup and view all the answers

    What is the approximate amount of carbon dioxide produced by cells per minute?

    <p>200 mL/min</p> Signup and view all the answers

    What is the approximate oxygen saturation of hemoglobin in the blood as it leaves the lungs?

    <p>65%</p> Signup and view all the answers

    What is the maximum number of oxygen molecules that can bind to a single hemoglobin molecule?

    <p>4</p> Signup and view all the answers

    What is the meaning of a hemoglobin being 25% saturated with oxygen?

    <p>One-quarter of the available iron binding sites are occupied by oxygen.</p> Signup and view all the answers

    During resting conditions, what percentage of the oxygen transported by hemoglobin is released as it passes through systemic capillaries?

    <p>60%</p> Signup and view all the answers

    What happens to the hemoglobin saturation in the blood leaving systemic capillaries during vigorous exercise?

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

    Which of the following is NOT a substance that hemoglobin transports relative to respiration activities?

    <p>Nitrogen bound to the globin</p> Signup and view all the answers

    What is the percentage of oxygen reserve bound to hemoglobin after passing through systemic capillaries?

    <p>30%</p> Signup and view all the answers

    How does the binding or release of one substance by hemoglobin influence its ability to bind or release the other two substances?

    <p>It causes a conformational change in the hemoglobin molecule that temporarily alters its shape.</p> Signup and view all the answers

    What is the most important variable that determines the percent oxygen saturation of hemoglobin?

    <p>The partial pressure of oxygen (PO2) in the blood</p> Signup and view all the answers

    If systemic cell Po2 decreases to 20 mm Hg during vigorous exercise, what happens to the hemoglobin saturation?

    <p>It decreases to 40%</p> Signup and view all the answers

    What purpose does the oxygen reserve serve in the body?

    <p>To provide additional oxygen to systemic cells under increased metabolic demands</p> Signup and view all the answers

    What is the meaning of hemoglobin being 100% saturated with oxygen?

    <p>All of the available iron binding sites on the hemoglobin molecules are occupied by oxygen.</p> Signup and view all the answers

    What is the approximate hemoglobin saturation at an altitude of 17,000 feet?

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

    At what altitude does altitude sickness typically occur for most individuals?

    <p>8,200 feet</p> Signup and view all the answers

    What are some milder symptoms of altitude sickness?

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

    How do changes in altitude initially affect hemoglobin saturation?

    <p>Small changes</p> Signup and view all the answers

    What is the approximate alveolar PO2 at an altitude of 9000 feet?

    <p>65 mm Hg</p> Signup and view all the answers

    At what altitude do adverse physiologic effects from a decrease in alveolar PO2, known as altitude sickness, start occurring?

    <p>6,600 feet</p> Signup and view all the answers

    What happens when CO2 and H+ are released from hemoglobin during pulmonary gas exchange?

    <p>It facilitates oxygen binding to hemoglobin</p> Signup and view all the answers

    What is the effect of CO2 and H+ binding to hemoglobin during tissue gas exchange?

    <p>It causes hemoglobin to release oxygen</p> Signup and view all the answers

    What is the effect of an increase in body temperature on hemoglobin during tissue gas exchange?

    <p>It causes hemoglobin to release more oxygen</p> Signup and view all the answers

    Which of the following statements about the role of hemoglobin in gas exchange is correct?

    <p>Hemoglobin transports oxygen and facilitates the transport of CO2</p> Signup and view all the answers

    What is the name given to the effect where the binding of CO2 and H+ to hemoglobin decreases its affinity for oxygen?

    <p>Bohr effect</p> Signup and view all the answers

    Which of the following statements about the transport of gases by hemoglobin is incorrect?

    <p>The binding of oxygen to hemoglobin causes a conformational change that facilitates CO2 release</p> Signup and view all the answers

    What is the primary factor determining the ability of blood to transport oxygen?

    <p>Solubility coefficient of oxygen in blood plasma</p> Signup and view all the answers

    What is hemoglobin referred to when it is bound to oxygen?

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

    Where does oxygen mainly attach within the blood for transport?

    <p>Hemoglobin within erythrocytes</p> Signup and view all the answers

    What is the term used for deoxygenated hemoglobin?

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

    Which term describes hemoglobin with carbon monoxide bound to it?

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

    What percentage of the total oxygen in the blood is typically dissolved in the plasma?

    <p>~2%</p> Signup and view all the answers

    At an altitude of approximately 9000 feet, the hemoglobin saturation would be:

    <p>91%</p> Signup and view all the answers

    What is the approximate hemoglobin saturation at an altitude of 17,000 feet?

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

    At what altitude do adverse physiologic effects from a decrease in alveolar Po2, known as altitude sickness, start occurring for some individuals?

    <p>6600 feet</p> Signup and view all the answers

    Which of the following is NOT mentioned as a milder symptom of altitude sickness?

    <p>Pulmonary edema</p> Signup and view all the answers

    What happens to hemoglobin saturation as altitude increases from sea level?

    <p>It decreases gradually</p> Signup and view all the answers

    What is the relationship between the binding of CO2 and H+ to hemoglobin and its affinity for oxygen during tissue gas exchange?

    <p>The binding of CO2 and H+ decreases hemoglobin's affinity for oxygen</p> Signup and view all the answers

    What effect does the release of CO2 and H+ from hemoglobin have during pulmonary gas exchange?

    <p>It increases the affinity of hemoglobin for oxygen</p> Signup and view all the answers

    During tissue gas exchange, the binding of CO2 and H+ to hemoglobin causes:

    <p>A decrease in hemoglobin's affinity for oxygen</p> Signup and view all the answers

    What is the effect of an increase in body temperature on hemoglobin during tissue gas exchange?

    <p>It decreases hemoglobin's affinity for oxygen</p> Signup and view all the answers

    Which of the following statements is correct regarding the transport of gases by hemoglobin?

    <p>Hemoglobin transports both oxygen and carbon dioxide</p> Signup and view all the answers

    What is the name given to the effect where the binding of CO2 and H+ to hemoglobin decreases its affinity for oxygen?

    <p>Bohr effect</p> Signup and view all the answers

    What is the primary substance within an erythrocyte?

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

    What is the primary role of carbonic anhydrase within erythrocytes in the transport of CO2?

    <p>It facilitates the conversion of CO2 to H2CO3, keeping the PCO2 relatively low and allowing continuous diffusion of CO2 from systemic cells into erythrocytes.</p> Signup and view all the answers

    What happens to the CO2 that diffuses into erythrocytes from systemic cells?

    <p>It is converted to H2CO3 by carbonic anhydrase, which dissociates into H+ and HCO3-.</p> Signup and view all the answers

    What is the role of the chloride shift in the transport of CO2?

    <p>It allows for the exchange of Cl- and HCO3- between erythrocytes and plasma, helping to buffer H+ and maintain pH.</p> Signup and view all the answers

    What happens to the H2CO3 formed within erythrocytes during CO2 transport?

    <p>It dissociates into CO2 and H2O, with the CO2 being expelled in the lungs.</p> Signup and view all the answers

    What is the primary function of hemoglobin in the transport of respiratory gases?

    <p>To bind and transport O2 from the lungs to systemic cells, and release it as needed.</p> Signup and view all the answers

    What happens to the CO2 that diffuses from the plasma into the alveoli during pulmonary gas exchange?

    <p>It is expelled from the body during expiration.</p> Signup and view all the answers

    What is the primary function of 2,3-BPG (2,3-biphosphoglycerate) in erythrocytes?

    <p>It decreases hemoglobin's affinity for oxygen.</p> Signup and view all the answers

    Which of the following factors does NOT influence the oxygen-hemoglobin saturation curve?

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

    What is the effect of an increase in temperature on hemoglobin's affinity for oxygen?

    <p>It decreases hemoglobin's affinity for oxygen.</p> Signup and view all the answers

    Which of the following hormones is NOT mentioned as stimulating the production of 2,3-BPG in erythrocytes?

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

    What is the effect of a decrease in pH (increase in H+ concentration) on hemoglobin's affinity for oxygen?

    <p>It decreases hemoglobin's affinity for oxygen.</p> Signup and view all the answers

    Which of the following statements about the binding of CO2 and H+ to hemoglobin is correct?

    <p>Binding of CO2 and H+ decreases hemoglobin's affinity for oxygen.</p> Signup and view all the answers

    Study Notes

    Erythrocytes and Hemoglobin

    • Erythrocytes are biconcave, flexible cells with no nucleus or mitochondria and few organelles.
    • They retain their plasma membrane, and their primary substance is hemoglobin.
    • An erythrocyte can be described as a "bag of hemoglobin."
    • There are approximately 20 trillion erythrocytes in the human body, each containing about 280 million hemoglobin molecules.

    Oxygen Transport

    • Oxygen is transported within blood from the alveoli to systemic cells in body tissues.
    • The ability of blood to transport oxygen is dependent upon two factors:
      • Solubility coefficient of oxygen in blood plasma (only 2% of oxygen is dissolved in plasma)
      • Presence of hemoglobin (Hb)
    • Hemoglobin binds to oxygen, forming oxyhemoglobin (HbO2), which allows for 98% of oxygen to be transported within erythrocytes.

    Carbon Dioxide Transport

    • Carbon dioxide is transported from systemic cells to the lungs through deoxygenated blood.
    • Carbon dioxide diffuses from systemic cells into the blood, then into pulmonary capillaries, and finally into the alveoli.
    • The majority of carbon dioxide is transported in the form of bicarbonate ions (HCO3-) within erythrocytes.

    Hemoglobin as a Transport Molecule

    • Hemoglobin transports three substances relative to respiration activities:
      • Oxygen attached to iron
      • Carbon dioxide bound to the globin
      • Hydrogen ions bound to the globin
    • The binding or release of one substance causes a conformational change in hemoglobin, influencing the ability to bind or release the other two substances.

    Oxygen-Hemoglobin Saturation Curve

    • The oxygen-hemoglobin saturation curve shows how PO2 influences the percent saturation of hemoglobin during tissue gas exchange.
    • Variables that influence the oxygen-hemoglobin saturation curve include:
      • Temperature (increased temperature decreases hemoglobin saturation)
      • pH (increased H+ concentration decreases hemoglobin saturation)
      • 2,3-BPG (increased concentration decreases hemoglobin saturation)
      • Altitude (increased altitude decreases hemoglobin saturation)

    Tissue Gas Exchange

    • Oxygen is released from hemoglobin during tissue gas exchange due to the conformational change caused by the binding of CO2 and H+.
    • This release of oxygen is known as the Bohr effect.
    • The oxygen-hemoglobin saturation curve helps to understand how PO2 influences the percent saturation of hemoglobin during tissue gas exchange.

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    Respiration: Gas Transport PDF

    Description

    Learn about the structure and function of erythrocytes - the red blood cells responsible for carrying oxygen in the body. Understand the unique characteristics of erythrocytes, including their lack of nucleus, mitochondria, and organelles, and their high hemoglobin content.

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