Embryology of respiratory system Flashcards

1
Q

Summary of the development of the respiratory system

A

Lung bud appears at week 4 from endoderm;

Week 4- 6 ; lung bud > trachea > bronchi > secondary bronchi > tertiary bronchi ; lungs grow into the pericardioperitoneal cavity

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2
Q

Connective tissue, pleura , muscles and cartilage of respiratory system comes from the …

A

Splanchnic mesoderm

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3
Q

Describe the pseudoglandular stage of lung maturation

A

Pseudoglandular ; 5-16 weeks, terminal bronchioles form (only components needed for gas exchange haven’t formed yet) ; pleuropericardial folds separate lungs from heart

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4
Q

Explain the relationship between the heart and lungs

A

Lobular and segmental veins → left pulmonary veins → oxygenated blood into LHS of heart → pumped out via aorta

deoxygenated blood enters RHS of heart via vena cava → pumped out via pulmonary artery → pulmonary artery branches into left and right versions via the pulmonary trunk

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5
Q

Epithelium and glands of trachea/pulmonary epithelium arise from the …

A

Endoderm

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6
Q

Describe the formation of the diaphragm

A

Septum transversal

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7
Q

Describe the canicular stage of lung formation

A

canalicular ; 16-26 weeks, vascularisation and further branching of terminal bronchioles into alveolar ducts ; initial formation of type 1 pneumocytes

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8
Q

Describe the terminal sac stage of lung formation

A

terminal sac ; 26 weeks to birth, epithelial cells of terminal sacs become flat and thin (type 1 alveolar epithelial cells) , capillaries come into close contact with the epithelial cells , type II alveolar cells form

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9
Q

Describe the alveolar stage of lung formation

A

alveolar ; 8 months pregnancy - childhood , increased surfactant production , few alveoli fully mature before birth , primordial alveoli continue maturing

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10
Q

The embryonic diaphragm is derived from 4 sites

name them

A

Septum transversum - located between the heart and liver ; goes on to form the central tendon

pleuroperitoneal membranes - forms the posteror and lateral parts of diaphragm

dorsal oesopheageal mesentery - forms the crura

body wall ; forms the peripheral parts of the diagram

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11
Q

Respiratory distress syndrome

what is it

causes

symptoms

treatment

A

Insufficient surfactant has been produced

high surface tension at air-blood interface

risk of alveoli collapsing during expiration

symptoms - rapid, laboured breathing

treatment - artificial surfactant/ glucocorticoids to stimulate surfactant prinduction

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12
Q

What is oesophagela atresia and tracheoesophageal fistulas ?

what are the problems they may cause ?

A

Abnormal separation of the oesophagus and trachea

atresia refers to the narrowing of oesophagus or trachea

fistula refers to an abnormal opening

this may lead to excessive amounts of fluid in respiratory tract ; gastric contents may reflux into trachea = coughing or choking or pneumonia

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13
Q

What are congenital cysts of the lungs?

what are the problems they may pose ?

A

occur when terminal bronchi are abnormallly dilated

usually at lung periphery

problems - poor drainage ; chronic lung infection

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14
Q

What is a congenital diaphragmatic hernia

A

Occur when pleuroperitoneal membrane fails to fuse with the other 3 components

most cases on left side

Leads to spilling of abdominal contents into the pleural cavity and compression of lungs ; hypo plasma of lungs

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