Carriage of Blood Gases and Haemoglobin Structure
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Questions and Answers

What initiates respiratory compensation for primary metabolic disorders?

  • Renal adjustments in bicarbonate excretion
  • Direct instruction from the brain's cortex
  • Increase in serum bicarbonate
  • Sensation of pH change by chemoreceptors (correct)

What occurs during a primary metabolic acidosis in the body?

  • Increased hypoventilation and decreased PCO2
  • Decrease in acid synthesis by the kidneys
  • Decreased minute ventilation and increased serum bicarbonate
  • Increased minute ventilation and decreased PCO2 (correct)

How long does the renal compensation for primary respiratory disorders typically take?

  • 6-12 hours (correct)
  • 24-48 hours
  • Immediately
  • Within 1-2 hours

In primary respiratory acidosis, which of the following occurs in the kidneys?

<p>Increased excretion of organic acids (D)</p> Signup and view all the answers

What is the role of the respiratory system in maintaining acid-base balance?

<p>It adjusts ventilation based on changes in pH levels. (D)</p> Signup and view all the answers

What effect does a decrease in pH have on the affinity of hemoglobin for oxygen?

<p>Increases the release of oxygen (C), Reduces the affinity for oxygen (D)</p> Signup and view all the answers

How does an increase in the temperature affect hemoglobin's affinity for oxygen?

<p>Decreases the affinity for oxygen (B)</p> Signup and view all the answers

Which condition is associated with an increase in the affinity of hemoglobin for oxygen?

<p>Low levels of 2,3-BPG (D)</p> Signup and view all the answers

What is the primary effect of elevated levels of carbon dioxide on hemoglobin's oxygen affinity?

<p>Decreases the affinity for oxygen (B)</p> Signup and view all the answers

What is the role of 2,3-BPG in red blood cells?

<p>To promote the release of remaining oxygen (B)</p> Signup and view all the answers

What form does haemoglobin take when it is deoxygenated?

<p>Tense form (C)</p> Signup and view all the answers

Which of the following statements about fetal hemoglobin (HbF) is true?

<p>It has a higher affinity for oxygen than maternal hemoglobin (D)</p> Signup and view all the answers

What happens to the affinity of hemoglobin for oxygen as the partial pressure of carbon dioxide (PCO2) decreases?

<p>Increases the affinity for oxygen (B)</p> Signup and view all the answers

What occurs to haemoglobin's structure when oxygen binds to it?

<p>It transitions from tense to relaxed form. (B)</p> Signup and view all the answers

At a partial pressure of 40 mmHg, what is the approximate saturation of haemoglobin with oxygen in systemic veins?

<p>77% (C)</p> Signup and view all the answers

What causes the shift of the oxygen-hemoglobin saturation curve to the right?

<p>High levels of 2,3-BPG (A)</p> Signup and view all the answers

How does the affinity of haemoglobin for oxygen change in systemic veins compared to the lungs?

<p>It is lower in systemic veins. (D)</p> Signup and view all the answers

What is the relationship between the partial pressure of oxygen and the saturation of haemoglobin?

<p>Sigmoid curve. (A)</p> Signup and view all the answers

What percentage saturation of haemoglobin with oxygen is expected in the alveoli at a partial pressure of 104 mmHg?

<p>Almost 100% (D)</p> Signup and view all the answers

What role does the bicarbonate buffer system play in the carriage of blood gases?

<p>It regulates blood pH. (D)</p> Signup and view all the answers

Which statement about oxygen transport and delivery is accurate?

<p>Blood oxygen levels affect the efficiency of aerobic respiration. (A)</p> Signup and view all the answers

What is the primary role of myoglobin in muscle tissues during exercise?

<p>To accept oxygen from hemoglobin when blood PO2 is low (C)</p> Signup and view all the answers

What is the main form in which carbon dioxide is transported in the blood?

<p>As bicarbonate ions (C)</p> Signup and view all the answers

Which enzyme catalyzes the conversion of carbon dioxide and water to bicarbonate and hydrogen ions?

<p>Carbonic anhydrase (D)</p> Signup and view all the answers

What does the bicarbonate ion primarily function as in the body?

<p>A key buffer system (A)</p> Signup and view all the answers

What happens to bicarbonate ions in the red blood cells during the transport of carbon dioxide?

<p>They are exchanged for chloride ions (A)</p> Signup and view all the answers

What physiological process produces bicarbonate as a result of a reversible chemical reaction?

<p>Krebs cycle metabolism (D)</p> Signup and view all the answers

Which of the following conditions can affect the affinity of hemoglobin for oxygen?

<p>pH level and carbon dioxide concentration (D)</p> Signup and view all the answers

What is the effect of exhalation of carbon dioxide on bicarbonate levels in the body?

<p>It decreases bicarbonate concentration (A)</p> Signup and view all the answers

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Flashcards

Acid-Base Balance

The body's ability to maintain a stable pH balance.

Metabolic Disorder

A type of acid-base disorder where the problem originates in the body's metabolism, such as diabetes or kidney failure.

Respiratory Disorder

A type of acid-base disorder where the problem originates in the lungs, such as pneumonia or emphysema.

Respiratory Compensation

The respiratory system's ability to adjust the amount of carbon dioxide (CO2) in the blood to compensate for changes in pH caused by metabolic disorders.

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Renal Compensation

The kidneys' ability to adjust the amount of bicarbonate (HCO3-) in the blood to compensate for changes in pH caused by respiratory disorders.

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Hemoglobin Affinity for Oxygen

Hemoglobin's ability to bind oxygen, influenced by oxygen's partial pressure, is called affinity.

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Sigmoid Curve of Oxygen Saturation

The relationship between oxygen partial pressure and hemoglobin saturation is S-shaped.

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Oxygen Saturation in the Lungs

In the lungs, oxygen partial pressure is high (around 104 mmHg), causing hemoglobin to be almost 100% saturated.

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Oxygen Saturation in Veins

In systemic veins, oxygen partial pressure is lower (around 40 mmHg), causing hemoglobin to be around 77% saturated.

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Hemoglobin's Affinity Changes

Hemoglobin's affinity for oxygen is higher in the lungs, where it needs to bind oxygen, and lower in the veins, where it needs to release oxygen.

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How Carbon Dioxide is Transported

Carbon dioxide (CO2) is transported in the blood in three ways: dissolved in plasma, bound to hemoglobin, or as bicarbonate ions (HCO3-)

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Bicarbonate Buffer System

The bicarbonate buffer system helps maintain blood pH by converting carbonic acid (H2CO3) into bicarbonate ions (HCO3-) and hydrogen ions (H+).

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Importance of the Bicarbonate Buffer System

The bicarbonate buffer system is essential for removing excess CO2 from the blood.

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Foetal Hb oxygen affinity

The ability of foetal haemoglobin to bind oxygen more readily than maternal haemoglobin, allowing for effective oxygen transfer from mother to foetus.

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Myoglobin function

A protein found in muscle tissue, with a higher affinity for oxygen than haemoglobin. It facilitates oxygen delivery to muscle cells during high metabolic demand.

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CO2 transport in blood

The process of carbon dioxide transport from tissues to the lungs for excretion, involving dissolved CO2, bicarbonate, and carbaminohemoglobin.

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Carbonic anhydrase

An enzyme that catalyzes the reversible reaction between carbon dioxide and water, forming carbonic acid, which then dissociates into bicarbonate and hydrogen ions. This plays a crucial role in CO2 transport and blood pH regulation.

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Chloride shift

The movement of bicarbonate ions out of red blood cells in exchange for chloride ions, a key step in CO2 transport and maintaining blood pH balance.

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Metabolic and respiratory influences on pH

Metabolic processes, such as cellular respiration, affect bicarbonate concentration in the blood, while respiratory processes influence carbon dioxide levels.

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Metabolic and respiratory disorders

Conditions where the equilibrium of the bicarbonate buffer system is disrupted, leading to imbalances in blood pH.

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Bohr Effect

When the pH of blood decreases (more acidic), the affinity of hemoglobin for oxygen decreases. This causes the oxygen dissociation curve to shift to the right.

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Effect of CO2 on Hemoglobin Oxygen Affinity

High blood carbon dioxide (PCO2) reduces hemoglobin's affinity for oxygen, causing the oxygen dissociation curve to shift to the right, leading to more oxygen release.

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Effect of Temperature on Hemoglobin Affinity

Increasing temperature decreases hemoglobin's affinity for oxygen, shifting the oxygen dissociation curve right. This increases oxygen delivery to tissues.

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Role of 2,3-BPG in Oxygen Release

2,3-Bisphosphoglycerate (2,3-BPG) is a molecule present in red blood cells that binds to deoxygenated hemoglobin, decreasing its affinity for oxygen, shifting the curve right.

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Foetal Hemoglobin and Oxygen Affinity

Foetal hemoglobin (HbF) has a higher affinity for oxygen compared to adult hemoglobin (HbA). This allows the foetus to extract oxygen from the mother's blood.

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Advantage of Bohr Effect

A decrease in pH (more acidic) decreases hemoglobin's affinity for oxygen, causing the oxygen dissociation curve to shift to the right. This allows for more oxygen delivery to tissues that are metabolically active and producing more CO2.

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Disadvantage of Bohr Effect

The Bohr effect can be disadvantageous in situations where blood pH is artificially lowered, such as in acidosis, as this can lead to reduced oxygen delivery to tissues.

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Factors Affecting Hemoglobin Oxygen Affinity

The ability of hemoglobin to bind and release oxygen is influenced by various factors, including pH, carbon dioxide concentration, temperature, and 2,3-BPG. These factors affect oxygen delivery to different tissues based on their metabolic needs.

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Study Notes

Carriage of Blood Gases

  • Blood carries oxygen and carbon dioxide.
  • Factors affecting oxygen carriage vary in different body areas.
  • The bicarbonate buffer system is crucial.

Blood Gas Transport

  • Lecture Outline:
    • How oxygen is carried in the blood
    • Factors affecting oxygen carriage and variations in body areas
    • How carbon dioxide is carried in the blood
    • Importance of the bicarbonate buffer system

Haemoglobin Structure

  • Haemoglobin A molecule:
    • Two alpha-globin chains (green)
    • Two beta-globin chains (yellow)
    • Each chain contains a haem-iron complex (blue)

Haemoglobin Oxygenation

  • Deoxygenated (tense) form:
    • Narrow crevice restricts oxygen access
  • Oxygenated (relaxed) form:
    • Oxygen binding causes shape change
    • Widens crevice for easier oxygen access

Hb Saturation and Partial Pressure

  • Relationship between Hb saturation and oxygen partial pressure is sigmoid.
  • Alveoli (high oxygen): Hb is nearly 100% saturated.
  • Systemic veins (low oxygen): Hb is about 77% saturated.
  • Oxygen released from Hb in systemic veins for use in aerobic respiration.
  • Systemic veins have lower oxygen affinity.

Effect of pH on Hb Affinity

  • Lower pH (higher hydrogen ion concentration):
    • Reduces Hb's affinity for oxygen.
    • Curve shifts to the right
    • More oxygen is released.

Effect of pCO2 on Hb Affinity

  • Higher pCO2:
    • Reduces Hb's affinity for oxygen
    • Curve shifts to the right
    • More oxygen is released

Effect of Temperature on Hb Affinity

  • Higher temperature: reduces affinity
  • Shifts curve to the right
  • More oxygen is released
  • Lower temperature: increases affinity
  • Shifts the curve to the left.

Effect of 2,3 DPG on Hb Affinity

  • 2,3-Bisphosphoglycerate (2,3-BPG) : three-carbon isomer of a glycolytic intermediate.
  • Present in red blood cells at 5 mmol/L
  • Binds to deoxygenated haemoglobin.
  • Promotes oxygen release.
  • 2,3-BPG increases within 1-2 hours in patients with chronic anaemia, then decreases with dialysis .

Foetal Hb Affinity for Oxygen

  • Foetal haemoglobin (HbF) has higher oxygen affinity than the adult haemoglobin (HbA)
  • Vital for oxygen transfer from the maternal blood supply.

Transfer of Oxygen to Tissues

  • Myoglobin:
    • Higher oxygen affinity than haemoglobin.
    • Can accept and release oxygen depending on the needed amount.

CO2 Transport in Blood

  • CO2 is a waste product of metabolism.
  • Transported to lungs for excretion.
  • Bicarbonate is the most significant form.
  • Carbonic anhydrase catalyzes the conversion of CO2 and water to carbonic acid (H2CO3), which, in turn, dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+).

Bicarbonate Ion Importance

  • Crucial buffer system in the body.
  • Absorbs or releases hydrogen ions to regulate pH.
  • Maintains constant hydrogen ion concentration, which affects:
    • Hb's affinity to oxygen
    • Enzyme reaction rates
    • Ionisation states of numerous substances.

Metabolic and Respiratory Disorders

  • Metabolic and Respiratory processes affect bicarbonate and pCO2.
  • Changes in ventilation compensate for metabolic disorders.
  • Renal excretion of acid compensates for respiratory disorders.
  • In primary acid-base disorders the underlying condition is identified by examining the pH, pCO2 and bicarbonate.

Learning Outcomes

  • Students will demonstrate the physiological process of respiration and its nervous system control.
  • Students will demonstrate the significance of maintaining normal acid-base balance within the body, and the respiratory system's role in it.

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Carriage of Blood Gases PDF - UM1010

Description

Explore the intricacies of how blood transports oxygen and carbon dioxide, focusing on haemoglobin's structure and function. This quiz covers essential aspects such as the factors affecting oxygen carriage, the importance of the bicarbonate buffer system, and the unique oxygenation properties of haemoglobin. Test your knowledge on these vital physiological processes.

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