Ch. 13 The Respiratory System

Marieb - Essentials of Human Anatomy & Physiology 13th Edition

Marieb13th EditionEssentials of Human Anatomy & PhysiologyISBN: 9780135624340Not the one you use?Change textbook

Marieb 13th Edition

Ch. 13 The Respiratory System

Problem 12

Chapter 13, Problem 12

What is it about the structure of the alveoli that makes them an ideal site for gas exchange?

Verified step by step guidance

Understand the function of alveoli: Alveoli are tiny air sacs in the lungs where gas exchange occurs between the air and the blood. Their structure is specialized to maximize efficiency in this process.

Examine the large surface area: The alveoli are numerous (about 300 million in the human lungs), and their spherical shape provides a large surface area for gas exchange. This large surface area allows for more oxygen and carbon dioxide to be exchanged simultaneously.

Consider the thin walls of alveoli: The walls of the alveoli are made of a single layer of epithelial cells, which minimizes the distance for diffusion of gases like oxygen and carbon dioxide. This thin barrier facilitates rapid gas exchange.

Analyze the surrounding capillaries: Alveoli are surrounded by a dense network of capillaries. These capillaries are also thin-walled, allowing for efficient diffusion of gases between the alveoli and the blood.

Note the moist environment: The alveoli are coated with a thin layer of fluid that helps dissolve gases, making it easier for oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood.

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Key Concepts

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

Alveolar Structure

The alveoli are tiny, balloon-like structures in the lungs that have a large surface area due to their numerous folds and clusters. This extensive surface area allows for more efficient gas exchange, as it maximizes the contact between air and blood. Additionally, the thin walls of the alveoli, composed of a single layer of epithelial cells, facilitate rapid diffusion of oxygen and carbon dioxide.

Surfactant

Surfactant is a substance produced by the cells lining the alveoli that reduces surface tension. This is crucial because it prevents the alveoli from collapsing and ensures they remain open for gas exchange. By lowering surface tension, surfactant also allows for easier expansion of the alveoli during inhalation, enhancing the efficiency of breathing.

Capillary Network

The alveoli are surrounded by a dense network of capillaries, which are tiny blood vessels that facilitate the exchange of gases. This close proximity between alveoli and capillaries ensures that oxygen can quickly diffuse into the blood while carbon dioxide diffuses out. The large surface area and thin walls of both the alveoli and capillaries optimize the efficiency of gas exchange, making it a rapid process.

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Related Practice

Textbook Question

As a result of a stroke, Mrs. Minnick's swallowing is uncoordinated. What detrimental effect might this have on her ability to breathe?

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Textbook Question

Clearly explain the difference between external and internal respiration.

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Textbook Question

Which of the following represents intrapleural pressure?

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Textbook Question

More than one choice may apply.

Which of the following changes will accompany the loss of lung elasticity associated with aging?

a. Increase in tidal volume

b. Increase in inspiratory reserve volume

c. Increase in residual volume

d. Increase in vital capacity

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Textbook Question

The contraction of the diaphragm and the external intercostal muscles begins inspiration. What happens, in terms of volume and pressure changes in the lungs, when these muscles contract?

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