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Flashcards in Respiratory Deck (18):

At what day does the Lung Bud form?

Lung bud forms at day 22.


In what direction does the lung bud grow?

The lung bud grows ventral aurally.


What separates the respiratory diverticulum from the foregut?

Tracheoesophageal ridges separate the respiratory diverticulum from the foregut.


When do the main bronchi and secondary bronchi form?

The main bronchi and secondary bronchi from during Week 5, resulting in 3 on the right, and 2 on the left.


When do the tertiary bronchi form and what do they supply?

During the 6th week further branches result in the formation of tertiary bronchi, each supplying a bronchopulmonary segment.

10 on the right. 8 on the left.


When do the first alveoli develop?

The first alveoli develop in week 36.


When are terminal and respiratory bronchioles formed.

Terminal bronchioles are formed by week 16 and respiratory bronchioles are formed by week 26.


Where do cartridge, smooth muscle, connective tissue and capillaries arise from?

They all arise from visceral mesoderm.


How is branching regulated?

Branching is regulated by the interaction of the epithelium (derived from foregut) with the overlying visceral mesoderm


What is pulmonary agenesis?

Pulmonary agenesis occurs when lung bud fails to split. Complete absence of bronchi and vasculature.

Bilateral agenesis is incompatible with life.


What is pulmonary hypoplasia?

Pulmonary hypoplasia is where the components are present but incompletely developed.


Histogenesis. Maturation of the lungs is divided into four periods, what are they?

1. Pseudoglandular
2. Canalicular
3. Terminal sac
4. Alveolar.


When does the pseudoglandular period happen?

Pseudoglandular period occurs from 5-17 weeks.
Branching of respiratory tree, to from terminal bronchioles.

Respiration not possible.


When does the canalicular period take place and what happens?

The canalicular period takes place from weeks 16 to 25.
Terminal bronchioles give rise to respiratory bronchioles which give rise to alveolar ducts.

Mesodermal tissue becomes highly vascularised.
Respiration possible towards end of period.


When does the terminal sac period occur?

The terminal sac period occurs from week 26 up until birth.


When is the alveolar period?

The alveolar periods occurs from 36 weeks to 8 years. Number of respiratory bronchioles and alveoli increase. 95% of mature alveoli do not develop until after birth.


What chemical forms lung buds

Retinoic acid


What regulates the branching of the bronchioles?

Epithelial mesocymal