Embryology of respiratory system Flashcards

1
Q

What happens at the end of week 4

A

The lateral body wall folds meet and fuse to close the ventral body wall
Cranial/caudal folding occurred due to rapid growth of the head and tail region
The gut tube is completely closed except where yolk sac is connected by vitelline duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is gastroschisis

A

Failure of the body wall to close in the abdominal region resulting in intestinal loops herniating into the amniotic cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is ectopia cordis

A

When the lateral body folds fail to close in the thoracic region causing the heart to lie on the outside of chest wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is bladder or cloacal exstropy

A

Abnormal body wall closure in the pelvic region

Cloacal extrophy is is more severe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What three regions is the gut tube divided into

A

Foregut
Midgut
Hindgut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When does the respiratory diverticulum appear

A

When the embryo is approx 4 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the respiratory diverticulum

A

Outgrowth of the foregut from its ventral wall
The epithelium present on the inner lining of the larynx, trachea, bronchi and the lungs is derived from endoderm
The rest of the lung tissue is derived from the visceral layer of the mesoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does the tracheoesophageal partitioning occur

A

Diverticulum starts to expand caudally
Causes two tracheoesophageal ridges to form
These grow towards each other and fuse to form the tracheoesophagael septum
Separating the foregut

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is fistula

A

An abnormal connection or passageway that connects two organs or vessels that do not usually connect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is atresia

A

Absence or abnormal narrowing of an opening or passageway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is the internal lining and the cartilages and muscles of the larynx derived from

A

Internal lining - endoderm

Cartilages and muscles are derived from the mesenchyme of the 4th and 6th pharyngeal arches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a mesenchyme

A

Loosely organised, mainly mesodermal embryonic tissue that develops into connective and skeletal tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the pharyngeal arches do

A

Gives rise to specific skeletal and muscular components of the head and neck, supplied by a particular cranial nerve, and its own artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How many pharyngeal arches are there

A

There are 5 arches

1,2,3,4 and 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens are the respiratory diverticulum separates from the foregut

A

Trachea as well as two primary bronchial buds form
At start of week 5, bronchial buds enlarge forming right and left primary bronchi
Then form 3 secondary bronchi of the right and 2 on the left
Then form 10 tertiary bronchi on right and 8 on the left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to the tertiary bronchi as lungs grow caudally

A

Further subdivision to form bronchioles which will continue to grow even in post natal life

17
Q

What are the 4 stages of lung maturation

A

Pseudoglandular
Canalicular
Terminal sac
Alveolar

18
Q

What is the pseudoglandular

A

Branching of the bronchial tree, forming many bronchioles up to terminal bronchioles
Bronchioles lined with cuboidal epithelium
Gas exchange not possible

19
Q

What is the canalicular

A

Each terminal branch divides into two or more respiratory bronchioles
These then divide into 3 to 6 alveolar ducts that become highly vascularised with capillaries
No gas exchange

20
Q

What happens at the start of terminal sac stage

A

Terminal sacs form
The epithelium of the terminal sacs is now a much thinner squamous epithelium
Capillaries establish close contact with the epithelium

21
Q

What happens from the 28 week onward regarding foetal breathing

A

Ther is sufficient numbers of alveolar sacs and capillaries to allow adequate gas exchange between air and primitive alveoli

22
Q

What happens in the last 2 months regarding terminal sacs

A

Number of terminal sacs increases

23
Q

How many terminal sacs are formed by birth in each lung

A

20-70 million

24
Q

What develops at the end of the 6th month during terminal sac stage

A

Type II alveolar epithelial cells develop

25
Q

What is surfactante

A

Essential lubricant for lung function
Forms phospholipid coat on the alveolar membranes
Lowers the surface tension at the air-alveolar interface, preventing the alveoli from collapsing

26
Q

What is respiratory distress syndrome

A

Absent or insufficient surfactant in premature babies

Primitive alveoli collapse causing respiratory distress syndrome

27
Q

What happens in alveolar stage

A

Mature alveoli form
Have well developed contact with capillaries as the epithelium lining thinned
After birth lungs grow due to increase in number of respiratory bronchioles and alveoli

28
Q

What is pulmonary hypoplasia

A

Reduced number of segments in the lung or alveoli

29
Q

Pulmonary agenesis

A

Absense of one or both lungs

Respiratory diverticulum fails to split into left and right bronchial buds and to continue growing