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Ch. 22 The Respiratory System
Marieb - Human Anatomy & Physiology 11th Edition
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
All textbooksMarieb, Hoehn 11th EditionCh. 22 The Respiratory SystemProblem 11
Chapter 22, Problem 11

In mouth-to-mouth artificial respiration, the rescuer blows air from his or her own respiratory system into that of the victim. Which of the following statements are correct?
(1) Expansion of the victim's lungs is brought about by blowing air in at higher than atmospheric pressure (positive-pressure breathing).
(2) During inflation of the lungs, the intrapleural pressure increases.
(3) This technique will not work if the victim has a hole in the chest wall, even if the lungs are intact.
(4) Expiration during this procedure depends on the elasticity of the alveolar and thoracic walls.
a. All of these
b. 1, 2, 4
c. 1, 2, 3
d. 1, 4

Verified step by step guidance
1
Step 1: Understand the concept of positive-pressure breathing. In mouth-to-mouth artificial respiration, the rescuer blows air into the victim's lungs at a pressure higher than atmospheric pressure. This forces the victim's lungs to expand, which is referred to as positive-pressure breathing.
Step 2: Analyze the role of intrapleural pressure during lung inflation. Normally, intrapleural pressure becomes less negative during inspiration, but in artificial respiration, the pressure increases due to the forced air being blown into the lungs.
Step 3: Consider the impact of a hole in the chest wall. If the victim has a hole in the chest wall, the intrapleural pressure cannot be maintained, leading to a loss of the pressure gradient required for lung expansion, even if the lungs themselves are intact. This would make the technique ineffective.
Step 4: Evaluate the role of elasticity in expiration. During expiration, the elastic recoil of the alveolar and thoracic walls allows the lungs to return to their resting state after being inflated. This is a passive process that does not require active effort from the victim.
Step 5: Review the options provided in the question and match them to the explanations above. Determine which statements are correct based on the physiological principles discussed.

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Key Concepts

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

Positive-Pressure Breathing

Positive-pressure breathing occurs when air is delivered into the lungs at a pressure greater than atmospheric pressure. This technique is essential in mouth-to-mouth artificial respiration, as it facilitates lung expansion by forcing air into the victim's respiratory system, thereby increasing lung volume and aiding in oxygenation.
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Intrapleural Pressure

Intrapleural pressure refers to the pressure within the pleural cavity surrounding the lungs. During lung inflation, this pressure typically decreases, allowing the lungs to expand. However, the question states that intrapleural pressure increases during inflation, which is a critical point to understand in the context of artificial respiration and lung mechanics.
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Elasticity of the Alveolar and Thoracic Walls

The elasticity of the alveolar and thoracic walls is crucial for normal respiratory function. During expiration, the elastic recoil of these structures helps expel air from the lungs. In the context of artificial respiration, this elasticity is vital for the effective return of air after positive pressure is applied, ensuring that the lungs can deflate properly.
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Textbook Question

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a. Chemically combined with the amino acids of hemoglobin as carbaminohemoglobin in the red blood cells

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c. As carbonic acid in the plasma

d. Chemically combined with the heme portion of Hb

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A baby holding its breath will:

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c. Suffer heart damage because of increased pressure in the carotid sinus and aortic arch areas

d. Be called a 'blue baby'

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a. In solution in the plasma

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Which of the following has the greatest stimulating effect on the respiratory centers in the brain?

a. Oxygen

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c. Calcium

d. Willpower

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