Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

22. The Respiratory System

Introduction to Lung Physiology

Anatomy & Physiology

22. The Respiratory System

Introduction to Lung Physiology

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Problem 14d

Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
When the PO₂ of arterial blood drops slightly, the percent saturation of Hb drops dramatically.

Verified step by step guidance

Understand the relationship between partial pressure of oxygen (Po₂) and hemoglobin (Hb) saturation. This is described by the oxygen-hemoglobin dissociation curve, which is sigmoidal in shape.

Recall that at high Po₂ levels (such as in arterial blood), hemoglobin is nearly fully saturated with oxygen. Small decreases in Po₂ in this range result in minimal changes in Hb saturation.

Recognize that dramatic drops in Hb saturation occur in the steep portion of the dissociation curve, which corresponds to lower Po₂ levels (such as in tissues).

Evaluate the statement: 'When the Po₂ of arterial blood drops slightly, the percent saturation of Hb drops dramatically.' Based on the dissociation curve, this is false because arterial blood Po₂ is in the flat portion of the curve, where Hb saturation remains relatively stable.

Correct the statement: 'When the Po₂ of arterial blood drops slightly, the percent saturation of Hb remains relatively stable due to the flat portion of the oxygen-hemoglobin dissociation curve.'

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Oxygen Saturation and Partial Pressure

Oxygen saturation refers to the percentage of hemoglobin molecules in the blood that are bound to oxygen. The partial pressure of oxygen (Po₂) is a measure of the amount of oxygen dissolved in the blood. A drop in Po₂ can lead to a decrease in oxygen saturation, but the relationship is not always dramatic, especially within certain physiological ranges.

Hemoglobin-Oxygen Dissociation Curve

The hemoglobin-oxygen dissociation curve illustrates how hemoglobin's affinity for oxygen changes with varying levels of Po₂. This curve is sigmoidal, indicating that small changes in Po₂ at higher levels can lead to relatively small changes in saturation, while larger changes occur at lower levels. Understanding this curve is crucial for interpreting how oxygen transport is affected by changes in Po₂.

Physiological Response to Hypoxia

Hypoxia refers to a deficiency in the amount of oxygen reaching the tissues. The body has various physiological responses to hypoxia, including increased heart rate and respiratory rate, as well as adjustments in hemoglobin affinity for oxygen. Recognizing these responses helps in understanding how the body compensates for changes in oxygen availability and the implications for oxygen saturation.