Session 12 - Embryology Flashcards Preview

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Flashcards in Session 12 - Embryology Deck (89)
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1
Q

What is embryology

A

Progression from a single cell to a baby in 9 months

2
Q

What do the fimbriae do

A

Their movements helps move the egg from the ovary into the Fallopian tube

3
Q

Why can the uterus reverse its contractions

A

To assist the movement of sperm

4
Q

Why must the opening of the cervix remain closed during pregnancy

A

So the bay doesn’t fall out. This is a cause of recurrent miscarriages

5
Q

What is spermatogenesis

A

The production of 4 spermatids from a spermatogonium

6
Q

What is produced in oogenesis

A

I big egg and 3 polar bodies

7
Q

Why is the egg cell so big

A

It contains lots of food to be able to survive 12 weeks before it’s supplied nutrients via the placenta

8
Q

When does meiosis II occur during oogenesis

A

After fertilisation

9
Q

When does meiosis I occur in oogenesis

A

In puberty just priori to ovulation

10
Q

What happens to the number of germ cells in females are they age

A

They reduce dramatically

11
Q

Why does the number of germ cells in females reduce

A

Many die or contribute to producing a big egg

12
Q

What helps the movement of the egg through the Fallopian tube

A

Contractions by the Fallopian tube

13
Q

How do sperm know which Fallopian tube to travel down

A

Thermotaxis

14
Q

True or false; cilia in the Fallopian tube assist the movement of sperm

A

False, they help the movement of the egg and so waft in the opposite direction to sperm making it harder

15
Q

What is capacitation of spermatids

A

When chemicals in the reproductive tract cause the heads of the sperm to change so that they swim faster. This then makes them capable to fertilise the egg

16
Q

What is the layer of cells covering the egg called

A

Corona radiata

17
Q

What is the outer layer of the egg called

A

Zona pellucida

18
Q

What happens when sperm burrow into the zona pellucida

A

They bind to sperm receptors triggering acrosomes to release digestive enzymes

19
Q

What happens to the zona pellucida once a sperm enters the egg

A

It hardens stopping other sperm entering

20
Q

What happens to the female genetic information once the egg is fertilised

A

It completes meiosis II and then forms a pronucleus

21
Q

What bring the 2 pronuclei together in fertilisation

A

Microtubules

22
Q

Where does fertilisation occur

A

Ampullary region of the Fallopian tube

23
Q

How long are sperm viable for

A

5 days

24
Q

How long are secondary oocytes viable for

A

12-24 hours

25
Q

When are antibodies against sperm produced

A

When they have contact with blood

26
Q

What does seminal fluid do

A

Helps the survival of sperm, contains immunosuppressants, increases likelihood of implantation

27
Q

What s the embryonic age

A

Time since fertilisation

28
Q

What is the gestational age

A

Time since last menstruation (embryonic age minus 2 weeks)

29
Q

What is the germinal Stage

A

Time from fertilisation to end of 2nd week

30
Q

What is the embryonic period

A

Time from 3rd to 8th week

31
Q

What is the foetal period

A

Time from 9th week to birth

32
Q

what is a zygote

A

fertilised ovum

33
Q

what is a morula

A

a cluster of 32 cells

34
Q

what will the trophoblast become

A

the placenta

35
Q

what is the function of the zona pellucida

A

stops implantation occurring in the wrong place and prevents the ball of eggs becoming too large as theres limited food

36
Q

true or false; the morula and blastocyst undergo both aerobic and anaerobic respiration

A

true

37
Q

what is histotrophic nutrition

A

nutrition provided to the embryo not from maternal blood

38
Q

how long does the embryo undergo histotrophic nutrition

A

for the first 12 weeks

39
Q

what is haemotrophic nutrition

A

nutrition provided by the mothers blood

40
Q

what does the morula differentiate into

A

an outer and inner cell mass

41
Q

when does the embryo develop into a blastocyst

A

when a blastocyst cavity form

42
Q

where does the embryo normally implant

A

superior posterior wall of uterine cavity

43
Q

what day does implantation occur

A

day 6

44
Q

what is an ectopic pregnancy

A

when implantation occurs at an abnormal site

45
Q

what is placenta previa

A

when implantation occurs at the internal os and so the placenta blocks the babys exit

46
Q

what does the outer cell mass differentiate into

A

trophoblast

47
Q

what does the inner cell mass differentiate into

A

embryoblast

48
Q

what does the trophoblast develop into

A

cytotrophoblast and synctiotrophoblast

49
Q

when does the trophoblast begin to differentiate

A

as it burrows into the endometrium wall

50
Q

what does the embryoblast develop into

A

bilaminar disc

51
Q

what are the 2 layer of the bilaminar disc

A

epiblast and hypoblast

52
Q

what develops between the cytotrophoblast and the epiblast

A

amniotic cavity

53
Q

What do cells from the hypoblast form

A

the yolk sac

54
Q

what membrane covers the yolk sac

A

exocoelomic membrane

55
Q

true or false the growth of the bilaminar disk is faster than the syncytiotrophoblast and cytotrophoblast

A

false - its actually the other way round

56
Q

what is the name of the small holes that form in the syncytiotrophoblast

A

lacunae

57
Q

what is the extra embryonic mesoderm

A

the new cells that form between the yolk sac and cytotrophoblast

58
Q

what happens to the extraembryonic membrane

A

a cavity forms creating the chorionic cavity

59
Q

what joins the bilaminar disk to the cytotrophoblast

A

connecting stalk

60
Q

during which period is there the greatest risk of congenital malformation

A

embryonic stage

61
Q

what is teratogensis

A

congenital malformation

62
Q

what stage occurs in the 3rd weed of development

A

gastrulation

63
Q

what occurs in gastrulation

A

the bilaminar disk is converted into a trilaminar disc

64
Q

what occurs at the primitive streak

A

cells from the epiblast migrate here and invaginate into the bilaminar disk forming a new layer

65
Q

what are names of the 3 layers of the trilaminar disc

A

ectoderm, mesoderm and endoderm

66
Q

what does the ectoderm develop into

A

brain and epidermis

67
Q

what does the mesoderm develop into

A

muscle, cartilage, bone and heart

68
Q

what does endoderm develop into

A

epitheial lining, respiratory tract

69
Q

what occurs at the primitive node

A

ciliated cells waft signals for leftsidedness to the left

70
Q

what occurs after gastrulation

A

neurulation

71
Q

what drive neurulation

A

the notochord

72
Q

what does the notochord do

A

convert the overlying ectoderm into neuroectoderm by releasing signals for these cells to differentiate to become thicker forming the neural plate

73
Q

how does the neural tube form

A

edges of the neural plate curl up to form the neural groove and then eventually the neural tube

74
Q

what does the following mesoderm develop into following the neural tube formation

A

somites

75
Q

what step occurs after neurulation

A

segmentation

76
Q

at what day do somites start to develop

A

day 20

77
Q

how many pairs of somites do you develop

A

31

78
Q

what do somites degrade and differentiate into

A

dermatome, myotome and sclerotome

79
Q

what is dermatome the precursor of

A

skin

80
Q

what is myotome the precursor of

A

muscle

81
Q

what is sclerotome the precursor for

A

bone

82
Q

what will the buccopharyngeal membrane develop into

A

mouth

83
Q

what will the cloacal membrane develop into

A

anus

84
Q

what will the intraembryonic coelom develop into

A

the serous membranes

85
Q

what stage occurs after segmentation

A

folding

86
Q

what type of folding occurs first?

A

cephalocaudal folding

87
Q

what drive cephalocaudal folding

A

growth of the neutral tube

88
Q

what type of folding occurs second

A

lateral folding

89
Q

what drives lateral folding

A

growth of somites