Cardiopulmonary Anatomy & Physiolo...

7th Edition
Des Jardins + 1 other
ISBN: 9781337794909



Cardiopulmonary Anatomy & Physiolo...

7th Edition
Des Jardins + 1 other
ISBN: 9781337794909
Textbook Problem

The lungs are usually sufficiently mature to support life by the

A. 24th week of gestation

B. 28th week of gestation

C. 32nd week of gestation

D. 36th week of gestation

Summary Introduction


Reproduction is one of the basic functions among all living organisms. The process varies from simple cellular division in case of unicellular bacteria to the very complex process of development of organs in higher animals. Development of the lungs takes a special place in the development of the fetus. Development of the lungs takes place in five phases. They are:

Embryonic phase

Pseudoglandular phase

Canalicular phase

Terminal saccular phase

Alveolar phase


Explanation for the correct answer:

Option (B) is 28th week of gestation. At about 28 weeks of gestation, the air blood interface develops to an extent that it can support life. The terminal saccules transform into alveoli. The alveolar cells differentiate into Type I and II cells, with the Type II cells increasing the production of pulmonary surfactant. Hence, option (B) is the correct answer

Explanation for the incorrect answer:

Option (A) is 24th week of gestation. The respiratory bronchioles continue to develop. Terminal saccules also start to appear, which forms the first step in the process of gas exchange. Traces of pulmonary surfactant can also be seen at this stage called the canalicular phase...

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