3. Embryology Flashcards

1
Q

When do the trachea and lungs begin to develop?

A

Beginning of 4th week

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2
Q

What does the laryngotracheal tube develop from?

A

Splanchnic mesoderm

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3
Q

What develops from the larygotracheal tube?

A

Tracheal buds

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4
Q

What is present at the end of the 4th week?

A

Bronchial buds

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5
Q

What is present at 8 weeks?

A

Trachea with bronchial buds and lungs split into lobes

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6
Q

What does the tubular outgrowth from the foregut develop into?

A

Trachea and lungs

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7
Q

Before the lungs buds begin to proliferate , what must happen to the trachea?

A

It must separate from the oesophagus

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8
Q

How are the pleural cavities and visceral and parietal pleuras formed?

A

The proliferating lung buds will invaginate the pleural cavities laterally forming them

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9
Q

What will begin to develop between the thorax and abdomen?

A

A transverse septal shelf

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10
Q

How many components is the septal shelf made up of?

A

4 components

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11
Q

What do the 4 components of the septal shelf fuse to form?

A

The diaphragm

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12
Q

How do congenital abnormalities affecting the respiratory system occur?

A

Things go wrong with the embryonic tracheal, lung and diaphragmatic formation

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13
Q

What does the visceral pleura form from?

A

The mesoderm which covers the outside of the lung

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14
Q

What does the parietal pleura develop from?

A

The somatic mesoderm covering the body wall from the inside

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15
Q

What are the stage of differentiation of lung buds?

A
  • Embryonic
  • Pseudo Glandular
  • Canalicular
  • Saccular
  • Alveolar
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16
Q

What does the septum transversum form?

A

Tendinous part of the diaphragm

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17
Q

What do the 2 pleuroperitoneal membranes form?

A

Muscular part of the diaphragm

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18
Q

What does the peripheral body wall muscle form?

A

Muscular part of the diaphragm

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19
Q

What does the mesentery of the oesophagus form?

A

Crura of diaphragm

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20
Q

What does folding of the embryo give rise to?

A

Primitive gut tube

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21
Q

What does the gut tube form from?

A

Endoderm

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22
Q

What is the relationship between the trachea/larynx and the oesophagus?

A

Trachea and larynx are always located anterior to the oesophagus

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23
Q

What does the respiratory primordium start as?

A

A median outgrowth (larnygotracheal groove/ diverticulum) from the anterior part of the foregut

24
Q

How does the diverticulum form the trachea and lung buds?

A

It becomes invested with mesoderm on its outside and enlarges

25
Q

What develops between the trachea and oesophagus?

A

Oesophagotracheal septum

26
Q

Fistula

A

-An abnormal or surgically made passage between a hollow or tubular organ and the body surface,
OR
-Between 2 hollow or tubular organs

27
Q

What is a common congenital abnormality?

A

Trachoesophageal fistula

28
Q

Atrasia

A

A condition in which an orifice or passage in the body is closed or absent

29
Q

What does the visceral pleura develop from?

A

The splanchnic mesoderm

30
Q

What does the parietal pleura form from?

A

Somatic mesoderm

31
Q

When do the lungs appear?

A

Around 26 days

32
Q

What is the first form the lungs take?

A

Form in the respiratory diverticulum in the ventral part of the digestive tract

33
Q

What does the respiratory diverticulum create?

A

A median trachea and 2 lateral pockets

34
Q

Where do the pulmonary arteries individuate?

A

The 6th aortic arch

35
Q

What happens during the pseudo glandular period?

A

Setup of all pulmonary structures except elements needed for gas exchange

36
Q

What happens during the canalicular stage?

A
  • The terminal bronchioles give rise tubes that make up respiratory part of the lung.
  • Differentiation of epithelium into cuboidal secretory cells which will synthesise surfactant and flat cells.
37
Q

What happens during the saccular stage?

A

Formation of alveolar sacs separated by primary septa. The alveolar sacs will be progressively divided into smaller subunits by secondary septs leading to the formation of alveoli.

38
Q

When does the pseudoglandular stage take place?

A

7-17 weeks

39
Q

When does the canalicular stage take place?

A

17-27 weeks

40
Q

When does the saccular stage take place?

A

27-40 weeks

41
Q

When does the alveolar stage take place?

A

32 weeks -8 years

42
Q

What happens during the alveolar stage?

A
  • Formation of alveoli from terminal sacs
  • Alveoli enlarge
  • Number of respiratory bronchioles (and alveolar ducts and alveoli) increase as lungs enlarge.
43
Q

What percentage of adult-like alveoli are formed postnatally?

A

About 95%

44
Q

What is another name for respiratory distress syndrome?

A

Hyaline membrane disease

45
Q

What is surfactant a mixture of?

A

Phospholipids and proteins

46
Q

What secretes surfactant?

A

Type II pneumocytes

47
Q

What does surfactant do?

A

Counteracts surface tension at air-alveolar surface

48
Q

What is a major cause of RDS?

A

Surfactant deficiency

49
Q

Give examples of respiratory congenital conditions?

A
  • RDS
  • Accessory lobes
  • Lobe of Azygous vein
  • Agenesis of lung
50
Q

Where is the septum transversum initially located?

A

Opposite C3-C5

51
Q

What is the root value of phrenic nerves?

A

C3-C5

52
Q

As the septum transversum migrates caudally what does it take with it?

A

Spinal nerves C3-C5

53
Q

What are the 3 major defects involved in congenital abnormalities of the diaphragm?

A
  • Failure of the diaphragm to completely close during development
  • Herniation of the abdominal contents into the chest
  • Pulmonary hypoplasia
54
Q

Hernia

A

General term used to describe a bulge or protrusion of an organ through the structure or muscle that usually contains it

55
Q

What are examples of diaphragmatic hernias?

A
  • Posterolateral Bochdalek hernia
  • Anterior Morgagni hernia
  • Central hernia
56
Q

What are examples of hiatal hernias?

A
  • Sliding hiatus hernia

- Paraesophageal hiatus hernia (rolling hiatus hernia)