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Age features of the lungs
Last reviewed: 23.04.2024
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In a newborn, the lungs have an irregular conical shape. Upper lobes are relatively small; the sizes of an average share of the right lung are equal to the sizes of the top share, and the bottom share rather big. At the second year of the child's life, the size of the lobes relative to each other becomes the same as in the adult.
The weight of both lungs in a newborn is 57 g (39 to 70 g), volume - 67 cm 3. The density of the non-breathing lung is 1.068 (lungs of the stillborn child are drowning in water), and the density of the lung of the breathing child is 0.490. Bronchial tree at the time of birth is mainly formed; at the 1 st year of life, its intensive growth is observed (the size of the lobar bronchi increases twofold, and the main ones - 1.5 times). During puberty, the growth of the bronchial tree is again reinforced. The sizes of all its parts by 20 years increase in 3,5-4 times (in comparison with a bronchial tree of the newborn). In people 40-45 years old, the bronchial tree is small.
Age involution of the bronchi begins after 50 years. In the elderly and senile age, the length and diameter of the lumen of many segmental bronchi slightly decrease, sometimes there appear distinct protrusions of their walls, tortuosity of the course.
Pulmonary acini in a newborn have a small number of small pulmonary alveoli. During the first year of life of the child and later the acinus grows due to the appearance of new alveolar courses and the formation of new pulmonary alveoli in the walls of already existing alveolar courses.
The formation of new branches of alveolar courses ends by 7-9 years, pulmonary alveoli - by 12-15 years. By this time, the dimensions of the alveoli are doubled. Formation of the pulmonary parenchyma is completed by 15-25 years. In the period from 25 to 40 years, the structure of the pulmonary acinus practically does not change. After 40 years, the aging of lung tissue gradually begins. The interalveolar septa are smoothed, the pulmonary alveoli become smaller, the alveolar courses merge with one another, the size of the acini grows.
In the process of growth and development of the lungs after birth, their volume increases: during the first year - 4 times, 8 years - 8 times, 12 years - 10 times, 20 years - 20 times (compared with volume of light newborn).
The boundaries of the lungs change with age. The apex of the lung in a newborn is at the level of the 1st rib. In the future, it protrudes over 1 rib and by 20-25 years is located 3-4 cm above 1 rib (1-2 cm above the clavicle). The lower border of the right and left lungs of a newborn is one rib higher than that of an adult. As the child's age increases, this border gradually falls. In the elderly (after 60 years) the lower border of the lung is 1-2 cm lower than in people aged 30-40 years.
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