5.8: Effects of Altered Gas Exchange
- Page ID
- 84002
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Biological Effects
In summary, essentially all aspects of the respiratory system involved in gas exchange are detrimentally affected by aging, resulting in a drop in the maximum rate of gas exchange. Furthermore, there is an overall decline in the efficiency of this system. Finally, the ability of the respiratory system to adjust the rate of gas exchange to meet body needs declines. These changes occur at a fairly steady rate throughout life.
As these changes occur, the maximum rate at which a person can perform physical activities declines, and a person who starts a vigorous activity such as running or climbing stairs will feel tired and out of breath sooner as age advances. Such an individual will not be able to perform at top speed for an extended period. Age changes in other systems, including the circulatory, skeletal, muscle, and nervous systems, may contribute to these decrements. The consequences of these effects can be reduced by raising one's pace gradually. Doing this provides extra time for respiratory functioning to adapt to the increased need for gas exchange. Also, going at a more moderate pace lowers the required rate of gas exchange.
Although aging causes reductions in several maximum respiratory values, these age changes are observed only when people require that the respiratory system function at maximum capacity. This system has such a great reserve capacity that the decline in maximum values caused by aging has essentially no effect on a person who engages in light or moderately vigorous activities. Thus, unless a person engages in activities such as very demanding physical work or highly competitive athletic events, age changes in respiratory functioning have little noticeable effect on his or her lifestyle. The aging respiratory system can provide adequate service in all but the most physically demanding situations.
Factors other than aging alter gas exchange. Also, much can be done to minimize age‑related reductions in the ability of the respiratory system to satisfy the need for gas exchange. For example, a sedentary lifestyle further limits respiration, while regular exercise keeps the decline in maximum minute volume small. Furthermore, incorporating adequate vigorous physical activity into one’s lifestyle can restore much of the decline in respiratory functioning caused by inactivity.
Another factor that adversely affects respiration is air pollution. Breathing polluted air seems to increase both the speed and severity of essentially every age change in the respiratory system mentioned thus far. People who smoke, live in areas where air quality is poor, or engage in occupations where the air contains dust, fine particles, or noxious chemicals have a much faster and greater loss of respiratory functioning. In addition, these individuals are at higher risk for developing respiratory diseases, including lung cancer, chronic bronchitis, and emphysema. Air pollutants can injure respiratory cells and tissues in several ways including physically, chemically, and through free radicals, microbes and immune responses. Radon damages lung tissues through the radiation it causes and the free radicals it induces. Breathing polluted air can be reduced by avoiding polluted areas; by not smoking; by wearing a protective mask; and by providing adequate ventilation with clean air in living and working areas.
Interactions
The biological effects of decreased gas exchange can affect other aspects of life. The nature and degree of these effects depend on the amount and importance of physical activity in a person’s life. Examples of people who may be affected more dramatically include people whose chief form of recreation and social contact is competitive sports and people whose jobs involve considerable physical exertion.
Finally, changes in gas exchange can be affected by other types of age changes. For example, upon retirement, a sedentary office worker may take up a physically demanding sport, which may provide the motivation to stop smoking. The result can be a slowing and even a temporary reversal of the decline in respiratory capacity.