Embryology

Question 1

Define Fetus

Answer 1

unborn offspring that develops from an embryo

Question 2

Define neonate

Answer 2

A baby that is less than 4 weeks old

Question 3

Define infant

Answer 3

Infancy is the period from birth until 2 years of age

Question 4

Define zygote

Answer 4

fusion of egg and sperm

Question 5

What does the zygote become once there are more than 16 cells?

Answer 5

Morula

Question 6

When does the yolk sac develop?

Answer 6

approximately 3 weeks after implantation

Question 7

What are the 3 layers of the blastocyst?

Answer 7

1. Ectoderm
2. Endoderm
3. Mesoderm

Question 8

What is gastrulation?

Answer 8

An early developmental process in which an embryo transforms from a one dimensional layer of epithelial cells and reorganizes into a multilayered and multidimensional structure

Question 9

What group of cells do the lungs originate from?

Answer 9

the endoderm

Question 10

Which portion of the gut tube do the lungs come from?

Answer 10

The lungs, esophagus, trachea and respiratory tract derive from the midgut

Question 11

What are the 5 stages of fetal lung development?

Answer 11

1. Embryonic
2. Pseudoglandular
3. Canalicular
4. Saccular
5. Alveolar

Question 12

What is the time frame for embryonic lung development?

Answer 12

0-8 weeks

Question 13

What is the time frame for pseudoglandular lung development?

Answer 13

8-16 weeks

Question 14

What is the time frame for canalicular lung development?

Answer 14

16-26 weeks

Question 15

What is the time frame for saccular lung development?

Answer 15

26-36 weeks

Question 16

What is the time from for alveolar lung development?

Answer 16

36+

Question 17

When are fetal breathing movements detected?

Answer 17

Can be detected as early as 10 weeks

Question 18

When are fetal breathing movements strong, organized and consistent?

Answer 18

30-40 weeks

Question 19

T/F: Fetal lungs are collapsed

Answer 19

False, fetal lungs are fluid filled

Question 20

How much fluid is produced by fetal lungs per day?

Answer 20

250-300 ml

Question 21

What occurs in the embryonic stage of lung development?

Answer 21

Lung buds, trachea, bronchi and central bronchial arteries are formed

Question 22

What occurs in the pseudoglandular stage of lung development?

Answer 22

1. Formation of terminal bronchioles
2. branching of bronchopulmonary trees as far as terminal bronchioles
3. Formation of Cilia
4. Mucus production
5. Vascular branching of arteries and veins alongside airways

Question 23

When do the Cilia form?

Answer 23

in the pseudoglandular stage of lung development

Question 24

When are the terminal bronchioles formed?

Answer 24

In the pseudoglandular stage of lung development

Question 25

What occurs in the Canalicular stage of lung development?

Answer 25

1. Development of primitive acini 2. Appearance of Type 1 and 2 pneumocytes with lamellar bodies 3. Surfactant production 4. Formation of air blood barrier

Question 26

T/F: Respiration is possible in the pseudoglandular stage?

Answer 26

False

Question 27

T/F: Respiration is possible in the canalicular phase

Answer 27

True

Question 28

What occurs in the saccular stage?

Answer 28

1. Formation, growth and branching of terminal saccules 2. Growth in number of lamellar bodies 3. Increase in Surfactant production 4. Growth of capillary networks around saccules 5. Formation of conducting and respiratory bronchioles completed

Question 29

In what stage do the capillary networks begin to form around saccules?

Answer 29

Saccular stage

Question 30

What occurs in the alveolar stage?

Answer 30

1. Formation and maturation of alveoli 2. Increased growth in diameter and number of alveoli

Question 31

At what stage is extrauterine viability possible and why cant it occur sooner?

Answer 31

1. Canalicular 2. The fetus is not viable because surfactant production has not begun, the fetus is incapable of respiration, and the airways are not developed enough yet

Question 32

Describe type 1 pneumocytes

Answer 32

1. Squamous cells 2. thin for gas exchange/diffusion 3. 97% of alveolar surface area

Question 33

Describe type 2 pneumocytes

Answer 33

1. Cuboidal cells 2. Production, storage, secretion and reuse of surfactant 3. Houses lamellar bodies which store surfactant

Question 34

How can we assess fetal lung development?

Answer 34

1. L/S ratio 2. Lamellar body Count 3. PG? 4. PC/DPPC

Question 35

What aspects can stimulate surfactant secretion?

Answer 35

Andosine Mechanical stretch Hormones

Question 36

What are the proteins that make up surfactant?

Answer 36

1. DPPC 2. Protein A (SP-A) 3. Protein D (SP-D) 4. Protein B SP-B) 5. Protein C (SP-C)

Question 37

What is the most abundant phospholipid in surfactant?

Answer 37

DPPC aka Lecithin

Question 38

What is the function of protein A?

Answer 38

1. Regulates synthesis and secretion of phospholipids 2. Promotes bacterial and viral clearance

Question 39

What is the function of protein D

Answer 39

Promotes bacterial and viral clearance