As you age, your skin will appear wrinkled, and your hair will also become grayer, but you can use a dye to cover your hair color and use cosmetic procedures to tighten your facial muscles. But maintaining a healthy respiratory system is not ever easy.
Although the respiratory system maintains adequate gas exchange and performs its other functions efficiently throughout life without any pathology, the cumulative effects of aging also weaken the respiratory system.
Let’s learn with resTORbio How Aging Affects The Respiratory System? to have a clearer view of human health problems, thereby adjusting our lifestyle to protect our body better.
How Aging Affects The Respiratory System?
The chest wall is fairly flexible in early life. As we age, there is a gradual increase in rib calcification. This is most noticeable in the anterior cartilaginous and coastal areas near the sternum (Figs 1, 2, and 3) and less so in the areas where the vertebral columns and ribs intersect. These changes result in a more rigid chest wall (Janssens and al., 1999).
As we age, our intervertebral disks become less strong and more fragile due to the increased weight of our bodies. Many older people experience the characteristic curvature in their thoracic spine. Hyperkyphosis can occur in some people, especially older women who have osteoporosis and muscle wastage.
The thoracic spine’s age-related curvature causes a narrowing between the vertebrae and between the bones. This gradually reduces the volume in the rib cage (Lowery and al., 2013).
A gradual decline in respiratory muscle strength is also seen with age. This is thought to be due to muscle mass loss in the intercostals and diaphragm. Immobile people and those sedentary living lives are more likely to lose muscle mass. Inactivity can lead to muscle weakness and wastage (Nigam et al., 2009).
These changes can lead to breathing becoming labored and the effectiveness of the coughing reflex decreasing, which in turn increases the risk for respiratory tract infections (Freitas, Kim, et al., 2010).
Because the 85m2 of its surface area is constantly in contact with the environment, the respiratory system is highly vulnerable to infection (West, 2008).
Every inhalation can introduce new infectious agents or irritants to the respiratory system. The ciliary escalator is an elaborate mechanism that clears particulate matter. Mucus covers the bronchial tree’s inner surface and traps inhaled particles like bacteria and dust. Marieb and Hoehn (2015).
Ciliated cells remove contaminated mucus from the lungs. This mucus is then swallowed by the pharynx (throat) and enters the acidic, sterilizing environment of the stomach.
Ineffective ciliary escalators can cause pathogens, mucous, and debris to not be cleared from the lungs as fast, increasing the chance of infection.
As we age, the frequency at which cilia beat decreases. This slows down the ciliary escalator. Studies of individuals aged 19 to 81 years have shown a clear decline in the ability to exhale particles (Svartengren and co-authors, 2005)
This could also be due to a gradual decrease in the number of cilia and ciliated cell counts in the airway (Levitzky 1984). Cigarette smoke, which is toxic to ciliated cell cells, will also reduce particle clearance.
Young people’s airways are very sensitive to mechanical stimulation. Inhaled particles often trigger a vigorous cough to expel and dislodge any irritants. The sensory receptors that monitor the airway may become less sensitive as we age, and the coughing reflex might not be activated.
This can increase the likelihood of pathogens or irritants reaching deep lung tissues, thereby increasing the possibility of RTIs. Even if the coughing reflex is activated, the decrease in inspiratory or expiratory muscle strength can reduce its effectiveness (Freitas and al., 2010).
The conduction zone is the airway between the nose and bronchioles. This is an anatomical dead area – an area where there is no gas exchange.
As we age, the cartilaginous rings holding the upper airways open slowly calcify, which causes the dead space to grow, especially the trachea and bronchi.
The amount of collagen and elastin in lung tissue is relatively constant. However, the lungs gradually lose elasticity and become more dilated.
This is due to changes in collagen and elastin fibers. These fibers either become cross-linked or degenerate, decreasing the elastic recoil of lung tissue. (Levitzky 1984).
As middle age approaches, the airways and lung tissue lose their elasticity. The size of the respiratory bronchioles and the alveolar ducts (tiny tubes that lead to the alveoli) increases. The elastic fibers in the alveolar dilate after 50 years.
This increases the structure and decreases the depth of alveoli. The alveolar walls can begin to crumble, and the air sacs may enlarge. This often results in a flattened appearance that reduces the total alveolar surface.
Healthy alveoli contain a resident population (cells that trap particulate matter that has reached the ends of the airways) of macrophages (Marieb & Hoehn 2015).
The number of macrophages in older people is lower, but they have more pro-inflammatory neutrophils. This means that their macrophages and neutrophils are more sensitive to granules and reactive oxygen molecules (superoxide anion), which can lead to inflammation in the lower respiratory tract. This could contribute to the loss of alveolar structure, common in older lungs (Sharma & Goodwin 2006).
People in their 90s have lost around 25% of the alveolar surface area. Smokers (and others who inhale particulate irritants) are more likely to experience these changes, leading to severe emphysema (Verbeken and al. 1992).
An increase in inflammatory mediators may contribute to allergic reactions. Multiple allergies and severe reactions like allergy-induced asthma are more common in older adults (Bom & Pinto 2009).
Even in the absence or presence of any pathology, pressure in the pulmonary arterial (wedge) slowly increases with age. This is due to arterial hypertrophy and loss of arterial elasticity.
These structural changes can lead to changes in lung function. These can be detected by spirometry or other techniques (Spirduso and al. 1995).
The residual volume (RV), or lungs volume, is the air left in the lungs following a forced expiration. It averages around 1.2L by age 25 and slowly increases with loss of lung elasticity.
Because they have less recoil during expiration, less elastic lungs can become more distended. This results in air trapping. The RV of a typical 70-year old will increase by 50% to approximately 1.8L (Lee and al., 2016).
Vital capacity (VC) is the amount of air that can easily be exhaled following a full inspiratory cycle. This is approximately 5L for an average 25-year-old man and a decline to 3.9L by age 65. It decreases for women from 3.5L to 2.8L (Spirduso and al. 1995).
These decreases are due to the gradual rise in chest-wall rigidity and the loss of respiratory muscles strength. The average non-smoker can expect VC to drop by 200ml per decade (American Lung Association 2016).
The total lung capacity refers to the volume of air in the lungs after full inspiration. It averages around 6L for men and 4.2L for women and doesn’t change much throughout your life. This could be due to the decreased lung elasticity being counterbalanced with the increased rigidity in the chest wall (Janssens 2005).
The volume of air exchanged during normal breathing is called the tidal volume. In the absence of any pathology, it is usually around 500ml. It does not increase with age. A 60-year old will use 20% more energy for normal breathing due to increased chest-wall rigidity (Janssens and colleagues 1999).
The effects that aging has on the respiratory system tract eventually leads to a decreased oxygen delivery to the blood and an increase in oxygen saturation. A pulse oximeter will give you a reading between 96-98% saturation at sea level for individuals under 70 years old. For those over 70, 94% would be considered normal (GP Notebook 2017, 2017).
Capacity for exercise
Kasch et al. 1993, 6-10% decrease in aerobic capacity per decade. A six-minute walk test, which measures how far one can walk in six minutes, shows that people aged 80 and over walk 200m less than 40 (Janssens 2005). This is due to a decline in cardiovascular function as we age (see Part 1).
Still, changes to the respiratory system, such as increased anatomical dead spaces and reduced VC, can lead to a decrease in exercise capacity. A lack of exercise can lead to a reduction in breathing efficiency. Sedentary people will experience a greater loss of respiratory muscle strength and mass (Pereira et al., 2014).
Susceptibility to RTIs
RTIs are most likely to occur in the elderly. Several reasons have been identified:
- The ciliary escalator reduces particulate matter and mucus clearance
- A decreased coughing reflex can increase the risk of mucus accumulation in the airway.
- Lung tissue with a reduced elastic recoil
Aspiration is one factor that increases the risk of RTIs in older adults. Half of the adults infuse their lower respiratory tract with oropharyngeal secretions while asleep. These aspirates can be easily cleared in younger adults who have efficient ciliary escalators or coughing reflexes.
However, older people may retain them in their lung tissue, increasing the chance of infection. Around 71% of patients with community-acquired pneumonia have aspiration problems. They are also common in older patients with dementia, stroke recovery, or fed via nasogastric tubes. (Janssens & Krause, 2004).
Viral and healthcare-associated RTIs
Winter is the best time to get viral RTIs. Older people are also at greater risk. Hospital-acquired pneumonia (nosocomial), which is more common in older people, increases hospital stay length.
Many older patients suffering from pneumonia don’t show any symptoms. They often present after a fall or bout with confusion (Janssens & Krause, 2004).
The Effects That Aging Has on the Respiratory System Include
These changes have increased the risk of:
- Lung infections such as pneumonia or bronchitis
- Breathing difficulties
- Low oxygen level
- Abnormal breathing patterns can lead to problems like sleep apnea, which is a condition where the body stops breathing during sleep.
Tips to Minimize the Effects of Aging Lungs
These changes are considered normal aging effects. However, you don’t have to accept the inevitable. It is possible to adopt healthy lifestyles that will reduce your chance of a decrease in lung function. These include:
- Regular aerobic exercise is a good idea. The kind that makes you breathe harder will give your lungs a workout.
- Limiting your exposure to secondhand smoke, dust, and other toxic substances
- Maintaining a healthy weight
- Make sure you get the flu shot and pneumonia vaccine as necessary.
With a normal person, you can fast for one week and do not drink water for three days, but you can’t hold your breath for more than 5 minutes. Hoping that our article can help you learn about what are the effects of aging on the pulmonary system? The respiratory system is very important to our body, so let’s daily exercise and a healthy lifestyle to protect themselves.