Development of lung disease Flashcards
describe the embryonic stage of lung development
this is within 3-8 weeks. here the lungs develop as an offshoot to the primitive foregut. the primary bronchial tubule is filled with liquid that continues to the mouth and makes up a major constitutive of amniotic fluid.
describe the pseudo-glandular stage of lung development
in this stage (5-7 weeks) the lungs have the beginnings of lobes and are similar to the adult thyroid gland as it is a fluid secreting organ. there is a primitive trachea and cartilage is beginning to form. gas exchange is still not possible but metabolic activity does occur.
describe the canalicular stage of lung development
at 16-25 weeks primitive acini are forming and the structure is less solid and more sponge like. gas exchange is just possible at the end of this period.
what lung development occurs in weeks 24-36?
this is the saccular stage. at this stage there is expansion of air spaces and surfactant is detectable in amniotic fluid.
at what stage is it thought that alveolar separation ceases?
at 3-8 years after birth. after this growth occurs as an increase in alveolar dimensions.
name some congenital lung diseases occurring in the embryonic stage of lung development.
> tracheal/laryngeal stenosis: the narrowing of a passage
pulmonary agenesis: incomplete formation of lung tissue
trachea-oesophageal fistula: when the trachea and oesophagus do not separate
what is a pulmonary sequestration?
non-functioning mass of normal lung issue which has no communication with the tracheobronchial tree. this develops in the pseudo-glandular phase of development.
when do cystic lesions form?
in the 2nd and 3rd stage of the pseudo-glandular stage
how does the diaphragm develop?
primitive tissues grow from the edge to the middle where they fuse, closure is normally at 18 weeks.
describe some diaphragmatic abnormalities?
> hernia
pulmonary hypoplasia and pulmonary hypertension which increases the likelihood of failure to transition from foetal to adult circulation.
eventration: when the muscle is not so tense so folds up into the thoracic cavity
what functional changes occur in the lungs at birth?
there is a change from fluid secreting to fluid absorbing and there is pulmonary vasodilation.
describe transient tachypnea of a new born
this is when there is a problem with the process of changing from fluid secreting to fluid absorbing resulting in a “wet” lung on a scan. this often results from a rapid change from secreting to absorbing for example in a c section.
describe problems resulting from problems in the surfactant system?
> neonatal lung disease: this is when there is a surfactant deficiency so that small alveoli collapse into larger ones
chronic neonatal lung disease: increased severity of bronchiolitis that could go on to develop COPD as the inflamed lung is replaced by fibrous tissue
what antenatal factors could give rise to adult lung disease?
> in utero exposure to nicotine
nutrition
low birth weight/premature birth
micronutrients/vitamins
