Respiratory System: A Tutorial Study Guide

Nicoladie Tam

• Publisher: Nicoladie Tam, Ph.D.
• eBook ISBN: 9781301805389
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

“Respiratory System” is a part of the college-level Principles of Biology course series textbooks. It is a tutorial written in questions and answers format to describe the anatomy and physiology of the respiratory system, including the gas exchange, partial pressure, lungs, breathing mechanisms, neural control of respiration, counter-current exchange system, and evolution of the respiratory system.

It is a study guide with in-depth explanations. Each section is a modular unit that is self-contained for easy reading. The principles and concepts are introduced systematically so students can learn and retain the materials intuitively.

1.1.Function of Respiratory System

Objectives

• Understand the function of gas exchange in respiration

 

Summary

The function of respiration is to provide gas exchange for an organism. Since most biological organisms require aerobic metabolism for basic survival function, these metabolic chemical reactions either produce or consume gases. (Most animals consume O₂ and produce CO₂ gases while most plants consume CO₂ and produce CO₂ during photosynthesis.) As a result, gas exchange is needed between the external and internal environments. The respiratory system provides a means for the organism to exchange gases efficiently and delivers the needed gases via the circulatory system.

 

Q&A

What are the functions of the respiratory system?

It is used for gas exchange.

Since most living organisms require oxygen for metabolism (except for anaerobic animals), gas exchange is vital for the survival of the organisms, both in plants and in animals. During aerobic metabolism for plants and animals, O2 is consumed while CO2 is produced as the byproduct. During anaerobic metabolism (an = no; aerobic = air), O2 is not required.

Note that plants also consume O₂ and produce CO₂ in its metabolism, especially in the non-photosynthetic parts, such as roots. Of course, photosynthesis will consume CO₂ and produce O₂ as the result.

What gas is needed for aerobic metabolism?

Oxygen is needed for aerobic metabolism.

Aerobic (aero = air) metabolism requires oxygen as the substrate for chemical reaction to occur. Thus, the delivery of oxygen to the tissue is essential for the survival of animals in the process called respiration.

What gas is released from aerobic metabolism?

Carbon dioxide is produces as a byproduct of aerobic metabolism.

Thus, the elimination of carbon dioxide from tissues as the result of metabolic byproduct is also essential in respiration.

What is anaerobic metabolism?

It is the metabolism, which does not require oxygen as the substrate.

Anaerobic (an = no; aero = air) metabolism does not require oxygen for the chemical reaction to occur. Anaerobic metabolism is not as efficient as aerobic metabolism. It was evolved before aerobic metabolism. The earliest metabolism derives energy from heat obtained from geothermal source at the bottom of ocean.

 

 

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1.2.Principles of Gas Diffusion

Objectives

• Understand the principle of gas diffusion
• Understand the principle of gas pressure difference

Summary

The principle of diffusion states that gas molecules move from high pressure to low. This is a macroscopic phenomenon of gas movement.

Microscopically, diffusion is resulted from the random motions of gas molecules moving in all directions bombarding each other called Brownian motions. Since high-pressure gas molecules are more energetic than low-pressure ones, therefore gases are more likely to move from high pressure to low. This results in the direction of diffusion – from high pressure to low pressure – at the macroscopic level.

Q&A

What is gas diffusion?

Gas diffusion is the movement of gas molecules often from high to low pressure at the macroscopic level.

The net movement of microscopic particles is from high to low concentration. For gas, the net movement is from high pressure to low pressure by the same principle.

How does gas move from high to low pressure?

It is due to Brownian motion at the microscopic level, resulting in a net movement from high to low pressure at the macroscopic level.

At the microscopic level, diffusion is due to random movement of gas molecules in all directions, bombarding each other. This results in what we called Brownian motion (because it was discovered by the scientist Mr. Brown).

Because high-pressure gases are more energetic, they move much faster than low-pressure gases. As a result, it is more likely for high-pressure gas molecules to move from high to low pressure than the opposite direction. This results in the macroscopic flow of gas from high pressure to low pressure called “diffusion.”

Do gas molecules move from low to high pressure too?

Yes, they do, except that the chance of gas molecules moving from low to high pressure is much lower than the opposite direction.

Gas molecules are more likely to move from high to low pressur...

Table of contents

• 1.1.Function of Respiratory System
• 1.2.Principles of Gas Diffusion
• 1.3.Principle of Partial Pressure of Gases
• 1.4.Principles of Gas Exchange
• 1.5.Principles of External Respiration and Internal Respiration
• 1.6.Regulation of Respiration
• 1.7.Mechanisms of Ventilation in Lungs
• 1.8.Chemo-Regulation of Respiration
• 1.9.Neural Control of Respiration
• 1.10.Principle of Counter-Current Exchange System
• 1.11.Principles of Oxygen Carrier: Hemoglobin
• 1.12.Hemoglobin Oxygen Dissociation Curve