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Flashcards in Embryology Deck (71):
1

What are the 3 main phases in human development?

Pre-embryonic
Embryonic
Foetal

2

During oogenesis, an ova is produced alongside what?

3 polar bodies

3

What part of the sperm enters the ova during fertilisation?

(pro)nucleus

4

What is the morula?

A solid ball of cells

5

What does the morula become?

A blastocyst

6

What is the name given to the accumulation of cells within a blastocyst?

The inner cell mass

7

What is the name of the outer lining of cells within the blastocyst?

Trophoblast

8

From the 1st cell division to the following cell divisions, what happens to the time taken for these cell division to occur?

The time decreases

9

What is the uterine tube lined with?

Ciliated epithelium

10

When does an eptopic pregnancy occur?

When the zygote cannot move through the uterine tube

11

Implantation takes place in what week of the pre-embryonic phase?

Week 2

12

Where does the blastocyst burrow down into during implantation?

The uterine wall (endometrium)

13

What does the trophoblast then form during week 2 of the pre-embryonic phase?

The chorion

14

What are the finger-like processes devloped by the chorion?

Chorionic villi

15

What secretes HCG?

The chorion

16

What does HCG indicate?

That a pregnancy is occurring

17

Where is the fetus nurtured?

The endometrium

18

When do maternal blood levels of HCG stop increasing?

Week 12

19

What happens to allow the epiblast and hypoblast to form?

The inner cell mass flattens

20

What 2 layers make up the bilaminar disc?

Epiblast
Hypoblast

21

What is the name of the cavity above the epiblast?

The amniotic cavity

22

What is the name of the cavity below the hypoblast?

The yolk sac

23

What is the purpose of the amniotic cavity?

To protect the embryo

24

What separates the maternal blood vessels from the foetal blood vessels?

The chorion

25

What are the 3 main functions of the placenta?

Foetal nutrition
Transport of waste and gases
Immunity

26

What forms the placenta?

The chorionic villi

27

In fraternal births, how many ova are released?

2

28

What is the name given to the dip in the epiblast?

The primitive streak

29

What is the name of the 3 layers formed during gastrulation?

Ectoderm
Mesoderm
Endoderm

30

What is the collective name given to the the ectoderm, the mesoderm and the endoderm?

The trilaminar disc

31

What is the name given to neural tube formation?

Neurulation

32

Where does the notochord sit?

In the mesoderm

33

What induces the ectodermal cells in the midline to form a neural line?

Notochord

34

What does the newly formed neural tube induce the mesoderm to do?

Thicken

35

What 3 parts do the mesoderm split into on either side?

Paraxial mesoderm
Intermediate mesoderm
Lateral plate mesoderm

36

Which mesoderm splits into the somatic and splanchnic mesoderms?

Lateral plate mesoderm

37

What does the paraxial mesoderm form?

Somites

38

Which mesoderm forms the urogenital system?

The intermediate plate mesoderm

39

How many blocks form to become somites on either side of the neural tube?

33

40

Why does the embryo start to fold laterally?

Due to the mesoderm becoming so heavy

41

What is the foetal position of the embryo due to?

The head and tail fold of the zygote

42

What 3 things does each somite divide into?

Dermatome
Myotome
Sclerotome

43

Where is the nucleus palposus of the IV discs formed from?

The notochord

44

What is teratology?

The study of when things go wrong during development

45

During which weeks is there the greatest sensitivity to teratogens?

Weeks 3-8

46

How do infectious agents affect the developing embryo?

Transfer through the placenta

47

In which week does folding of the embryo take place?

Week 3

48

What is the origin of the formation of the gut tube?

The endoderm

49

What does longitudinal folding of the embryo give rise to?

Foregut and hindgut

50

At what week gestation do the lungs develop?

4 weeks gestation

51

At what week of development do the nasal pits deepen?

Week 6

52

What does the respiratory primordium start out as?

A median outgrowth

53

What does the larynx develop from?

The endoderm

54

Where does the cartilage of the larynx develop from?

The 4th-6th pairs of pharyngeal arches

55

Where does the epiglottis develop from?

The caudal part of the hypopharyngeal eminence

56

What is caused as a result of recanalization failure?

Laryngeal atresia

57

What does laryngeal atresia cause the lower airways to do?

Dilate

58

How can laryngeal atresia be detected?

Through ultrasound

59

What gives rise to the laryngotracheal diverticulum?

The laryngotracheal groove

60

Lung bud formation is a result of what?

Ventral outgrowth of the foregut endoderm

61

When does a trachea-oesophageal fistula occur?

When there is incomplete separation of the trachea and oesophagus

62

Why won't a foetus survive if born during the pseudo-glandular stage of development?

As the major gas exchange elements have not formed

63

During the canalicular stage, what happens to the lumina of the bronchi and terminal bronchioles?

They enlarge

64

During what week of embryonic development, do the terminal sacs become lined with type 1 and 2 pneumocytes?

26 weeks

65

Which type of pneumocytes secrete surfactant?

Type 2

66

What is surfactant a mixture of?

Phospholipids and proteins

67

What does surfactant prevent the collapse of?

Alveoli sacs during exhalation

68

What is the major cause of respiratory distress syndrome?

Surfactant deficiency

69

What happens to the number of alveoli at 8 years old?

They reach the adult number of alveoli

70

What are the 4 embryonic components that form the diaphragm?

Septum transversum
Pleuroperitoneal membranes
Dorsal mesentry of oesophagus
Muscular ingrowth from lateral body walls

71

Where is the septum transversum initially located?

Opposite the somites of C3-5