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Questions and Answers
What happens to hemoglobin's affinity for O2 when the pH decreases?
The PCO2 levels have no effect on hemoglobin saturation.
False
In vigorous physical exercise, what metabolic acid is primarily produced by contracting muscles?
lactic acid
Active tissue consumes O2 at an accelerated rate, leading to a drop in PO2 of about _____ mmHg.
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Match the following factors with their effect on hemoglobin affinity for oxygen:
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What happens to hemoglobin affinity for oxygen when pH decreases?
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An increase in carbon dioxide levels shifts the hemoglobin-oxygen dissociation curve to the left.
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What effect does an increase in temperature have on hemoglobin's affinity for oxygen?
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In conditions of hypothermia, more oxygen remains ___ to hemoglobin.
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What role does 2,3-DPG play in hemoglobin function?
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Carbon monoxide has a weaker affinity for hemoglobin than oxygen.
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A rightward shift in the O2-Hb dissociation curve means that at every level of PO2, ___ oxygen is released than normal.
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Match the following conditions with their effects on hemoglobin's affinity for oxygen:
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What percentage of oxygen is carried by hemoglobin in the bloodstream?
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The normal hemoglobin level for adult males is lower than that for adult females.
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What is the primary role of hemoglobin in the body?
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Each hemoglobin molecule can carry up to _____ molecules of O2.
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What is formed when hemoglobin binds with oxygen?
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What is the primary component of hemoglobin that allows it to transport oxygen?
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Hemoglobin can carry both oxygen and carbon dioxide simultaneously.
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What physiological role does hemoglobin play in the body?
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Each hemoglobin molecule can carry up to _____ molecules of O2.
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What is the normal hemoglobin concentration for adult females?
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Match the following hemoglobin states with their characteristics:
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The partial pressure of oxygen in the lungs is approximately 50 mm Hg.
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How many grams per deciliter (g/dL) of hemoglobin is considered normal for adult males?
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Study Notes
Hemoglobin and Oxygen Transport
- The human body requires 250ml of O2 per minute at rest.
- Oxygen transport is primarily facilitated by hemoglobin (Hb) within red blood cells (RBCs).
- A single RBC contains 280 million Hb molecules, each capable of binding four oxygen molecules.
- Normal hemoglobin levels in adult males range from 14–18 g/dL, while adult females typically have levels between 12–16 g/dL.
Hemoglobin Structure
- Hemoglobin is a complex protein with a quaternary structure.
- It comprises two alpha chains and two beta chains.
- Each Hb chain contains a heme molecule, which holds an iron ion capable of interacting with oxygen.
- The iron-oxygen interaction is weak and reversible, allowing for efficient oxygen binding and release.
- CO2 and O2 bind to distinct sites on the hemoglobin protein.
Hemoglobin Functioning
- Hb saturation refers to the amount of oxygen bound to each Hb molecule, influenced by plasma O2 levels.
- Hb bound to oxygen is called oxyhemoglobin, while Hb without oxygen is deoxyhemoglobin.
- In tissues with elevated PCO2 levels, Hb binds to CO2, forming HbCO2.
- Hb plays a critical role in transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs.
Oxygen-Hemoglobin Dissociation Curve
- This graph illustrates the relationship between oxygen saturation and partial pressure of oxygen (PO2).
- At a PO2 of 100 mmHg (typical in the lungs), Hb has a high affinity for oxygen, achieving near 98% saturation.
- In tissues, the typical PO2 is 40 mmHg, leading to a lower Hb affinity for oxygen and oxygen release.
- Even after leaving the tissues, Hb remains approximately 75% saturated, providing a reserve for increased tissue demand.
Factors Affecting Hemoglobin Saturation
- PO2: Plays a relatively minor role.
-
Blood pH:
- Decreased pH (acidity) reduces Hb affinity for oxygen, shifting the curve to the right.
- Increased pH (alkalinity) increases Hb affinity for oxygen, shifting the curve to the left.
-
Temperature:
- Increased temperature reduces Hb affinity for oxygen, shifting the curve to the right.
- Decreased temperature increases Hb affinity for oxygen, shifting the curve to the left.
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PCO2:
- Increased PCO2 reduces Hb affinity for oxygen, shifting the curve to the right.
- Decreased PCO2 increases Hb affinity for oxygen, shifting the curve to the left.
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2,3-Bisphosphoglycerate (2,3-BPG):
- Increased BPG reduces Hb affinity for oxygen, shifting the curve to the right.
- Decreased BPG increases Hb affinity for oxygen, shifting the curve to the left.
Shifts in the Oxygen-Hemoglobin Dissociation Curve
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Right Shift:
- Increased oxygen release at tissues.
- Decreased oxygen uptake in the lungs.
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Left Shift:
- Increased oxygen uptake in the lungs.
- Decreased oxygen release at tissues.
Carbon Monoxide (CO)
- CO is produced endogenously in small amounts and acts as a neurotransmitter.
- Environmental CO is a major concern, released from sources such as car exhaust, oil lamps, and natural gas.
- CO has a 210 times stronger affinity for Hb than oxygen, effectively blocking oxygen binding.
- CO poisoning is a serious health hazard as it prevents oxygen transport throughout the body.
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Description
Explore the fascinating role of hemoglobin in the human body and its importance in oxygen transport. This quiz covers the structure, functioning, and normal levels of hemoglobin in adults. Test your knowledge and gain insights into how this protein sustains life by efficiently transporting oxygen.
