14. Embryology of the respiratory system

Question 1

What are the 4 stages from zygote to blastocyst?

Answer 1

1. Fertilisation: ovum surrounded by sperm
2. Zygote: nucleus of the sperm enters and fuses with nucleus of ovum
3. Morula: ball of cells undergoing mitosis
4. Blastocyst: number of cells increases leading to blastocystic cavity, cells accumulate at one end= forming an inner cell mass. Trophoblast is the layer of cell that surrounds it

Question 2

Answer 2

Question 3

Where do the zygote -> blastocyst stages happen?

Answer 3

Zygote will form near ovary then travel to fallopian tube to uterine cavity into endometrium = blastocyst

Question 4

What is an ectopic pregnancy?

Answer 4

If loose cillia function and so the zygote is stuck outside the uterus

Question 5

What is the chorion?

Answer 5

After blastocyst, 2 layers of trophoblast will form the placenta and secrete HCG to make sure endometrium doesn’t get shed

Question 6

Answer 6

Question 7

Answer 7

Question 8

Answer 8

Question 9

Answer 9

Question 10

Answer 10

Question 11

What is thalidomide?

Answer 11

In 1960s, people weren’t sleeping well so used a tranquiliser to alleviate morning sickness
babies were delivered with small limbs: teratogens= environmental factors caused abnormal development

Question 12

Where do lungs form from?

Answer 12

endoderm from the foregut

Question 13

Answer 13

Question 14

What happens if the trachea doesn’t separate from the oesophagus in embryology?

Answer 14

Tracheosophageal fistula and oesophageal atresia

Question 15

Answer 15

Pleuropericardial folds- flaps of body wall at the level of the primitive pericardial cavity which grow medially and fuse with the ventral surface of the foregut mesoderm.

Question 16

What is the formation of the septum transversum, pleuropericardial folds, pericardioperitoneal canals and pleuroperitoneal folds?

Answer 16

1. Septum transversum divides pericardial cavity with peritoneal (abdomen) cavity
2. Pleuropericardial folds fuse with each other and divides the pericardial cavity and pleural cavities.
3. Pericardioperitoneal canal was used for the pericardial and peritoneal cavities to communicate
4. But the Pleuroperitoneal folds closes the pericardioperitoneal canals.

These canals will become the pleural cavities.
These canals lie dorsally to the septum transversum. They interconnect the primitive pericardial cavity and the peritoneal cavity
The pericardioperitoneal folds expand over septum transversum and fuse with each other. Separating the
the pleural cavity with the peritoneal cavity.

Question 17

What is the pericardioperitoneal canal?

Answer 17

openings posteriorly between the primitive pericardial and peritoneal cavities

Question 18

What happens from weeks 4-7 in age development of the lungs? What period is it called?

Answer 18

The embryonic period, lung bud forms trachea and larynx form

Question 19

Answer 19

Question 20

Answer 20

Question 21

What is neonatal respiratory distress syndrome?

Answer 21

Surfactant deficiency, alveolis collapse

Question 22

What is lung agenesis?

Answer 22

Lung buds don’t form due to insufficient mesoderm (teratogens)

Question 23

What is pulmonary hypoplasia?

Answer 23

Incomplete development of the lung

Question 24

What is diaphragmatic hernia?

Answer 24

Structures herniate through diaphragm into chest wall cavity

Question 25

What is hiatus hernia?

Answer 25

Hernia in oesophagus

Question 26

What are the 4 embryology stages of the development of the diaphragm?

Answer 26