Chapter 1. Chapter 28: Respiratory System

1.1 Introduction

Welcome to the Interactive Study Guide for Chapter 28: Respiratory System! This Study Guide will help you master your understanding of the chapter's Driving Questions, using interactive Infographics and activities, as well as targeted assessment questions. Click "Next" to get started, or select a Driving Question from the drop-down menu to the right.

DRIVING QUESTIONS

• What structures make up the respiratory system?
• How do the respiratory and cardiovascular systems cooperate to deliver oxygen to body cells and remove carbon dioxide from tissues?
• What factors influence the oxygen-carrying capacity of blood and breathing rate?
• How can scientific knowledge of the respiratory system be used to design training regimens for elite athletes?

1.2 Driving Question 1:

Why should you care?

Every cell in your body needs oxygen to perform aerobic respiration to make ATP. Without ATP, the body’s energy currency, cells would not be able to function, tissues and organs would stop working, and death would follow. The ability to utilize oxygen to produce ATP evolved around 2 billion years ago as eukaryotic organisms arose. Methods to obtain oxygen from the environment have been evolving ever since. As large, multicellular eukaryotic organisms, humans need a way not only to obtain oxygen from the atmosphere but also to deliver it to all areas of the body. The respiratory system, in conjunction with the circulatory system, is nature’s eloquent answer to this complex issue.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Draw and describe the major structures of the respiratory system.
2. Explain the mechanics of breathing.

Infographic Focus

The Infographics most pertinent to the Driving Question are 28.1 and 28.6.

Draw and describe the major structures of the respiratory system.

Question 1.1

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• pharynx: throat, where the inhaled air goes first
• larynx: also called the voice box, opening to the lower respiratory tract; air passes through this region and causes vibrations that we hear as sound
• trachea: large, ridged airway that leads to the lungs
• lungs: site of gas exchange between air and blood; major organs of the respiratory system
• bronchi: the two branches from the trachea, leading one to each lung
• bronchioles: smaller airways that branch off the bronchi
• alveoli: air sacs at the end of bronchioles that are the site of the gas exchange, closely interacting with capillaries
• diaphragm: sheet of muscle that controls breathing by contracting (breathe in) and relaxing (breathe out)

Question 1.2

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A tracheotomy opens a direct path for air to flow into the trachea and to the lungs. Since the usual pathway through the nose and mouth is blocked, this procedure allows the person to breathe until the block can be removed.

Question 1.3

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Capillaries of the circulatory system closely associate with alveoli, allowing oxygen and carbon dioxide exchange between the two.

1.3 Driving Question 2:

Why should you care?

Now that you know why oxygen is important for eukaryotic life and how humans obtain it from the atmosphere, there remains the problem of how to deliver the oxygen to all cells of the body. Humans are not like frogs; we cannot absorb oxygen through our skin and thus ensure that it reaches all parts of the body. However, the circulatory system is an excellent vehicle for oxygen transport. Knowing how these two important systems interact will help you understand how some athletes take advantage of this relationship to enhance performance.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the interaction of the respiratory and circulatory systems.
2. Predict how problems in one system may affect the other.

Infographic Focus

The Infographics most pertinent to the Driving Question are 28.2, 28.3, and 28.8.

1.4 Driving Question 3:

Why should you care?

So how do the circulatory system and respiratory system actually deliver oxygen to and remove carbon dioxide from the body? The answer is simple: blood. The blood contains enucleated, biconcave, flexible little cells called red blood cells that are essentially the “Pony Express” of oxygen transport. Blood also dissolves carbon dioxide and carries it away for expulsion from the body. Needless to say, without blood, a person would be not just very pale but very dead. So how does the blood keep everything in balance?

What should you know?

To fully answer this Driving Question, you should be able to:

1. Identify conditions that raise or lower the oxygen-carrying capacity of blood.
2. Explain how breathing rate influences the amount of carbon dioxide in the blood.

Infographic Focus

The Infographics most pertinent to the Driving Question are 28.3, 28.4, 28.8 and 28.9.

1.5 Driving Question 4:

Why should you care?

Elite athletes are typically people who year round, endure grueling physical workouts, and look for any reasonable and preferably ethical training method to give them a competitive advantage against their opponents. In a beautiful example of the scientific process in action, scientists and others noticed that during the 1968 Olympic Games in Mexico City, endurance athletes were falling short of expectations while other athletes, like sprinters and long jumpers, were breaking records left and right. This observation, the first step in the scientific method, led to questions and hypotheses as to why some athletes were successful and others were underperforming. Several experiments later, scientists, and now some trainers and athletes, believe that altitude affects athletic performance. In this case, the knowledge of how the respiratory system transports oxygen to the body and the effect of high altitude on this transport has led to specific training regimens for elite athletes that may give them an edge over their competition. Whether or not these training regimens are ethical is another matter.

What should you know?

To fully answer this Driving Question, you should be able to:

1. Describe the live high, train low method utilized by some athletes and how this method is supposed to increase athletic ability.
2. Interpret the data describing the effects of altitude training on athletic performance.
3. Discuss whether using scientific knowledge to design training regimens is ethical.

Infographic Focus

The Infographics most pertinent to the Driving Question are 28.4, 28.5, 28.7, and 28.9.

Interpret the data describing the effects of altitude training on athletic performance.

Consider the graphs in Infographic 28.7.

Question 1.25

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According to the Infographic, this study looked at the effect of altitude training on athletic performance of 22 elite distance runners. Maximal oxygen uptake and 3,000-meter race performance were measured before and after a 4-week live high, train low regimen. The live high aspect was performed at 2,500 meters above sea level, and the train low aspect was performed at 1,250 meters above sea level.

Question 1.26

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The researchers saw that the live high, train low regimen improved the athletes’ maximum oxygen uptake and reduced the time it took for them to run 3,000 meters; both results were statistically significant.

Question 1.27

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This experiment shows a correlation between altitude training and improved performance. Since many other variables could be contributing to the improved performance, not just increased oxygen uptake, it is hard to say that the altitude training is the direct cause. It may be something else in the environment, or perhaps the athletes sleep better at higher altitudes. Maybe it is actually a placebo effect: the athletes know that they are supposed to perform better after undergoing this training, so they do just that. To show causation, the researchers would first have to pinpoint what it was about the altitude training that improved the athletes’ performance. If they found that key factor, they could run controlled experiments to see if the presence or absence of that factor made a difference in the performance of the distance runners.