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Foundations Of Medicine > 12.4 Embryo Development > Flashcards

12.4 Embryo Development Flashcards

1
Q

What are the three stages of prenatal development?

A
  • Germinal
  • Embyronic
  • Foetal
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2
Q

How long is the germinal stage?

A

2 weeks (weeks 1-2)

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3
Q

How long is the embryonic stage?

A

6 weeks (weeks 3-8)

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4
Q

How long is the foetal stage?

A

32 weeks (weeks 9-38)

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5
Q

Describe the germinal stage of prenatal development

A

Primitive germ layers are formed (What is this?)

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6
Q

Describe the embryonic stage of prenatal development

A

Major organ systems come into existence (developing human is now called embryo)

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7
Q

Explain clinical vs developmental age

A

Clinical: Since LMP
Developmental: 14 days after LMP (since this is usually how long after period before fertilization)

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8
Q

What is the sperm nucleus called when it increases in size inside the ovum?

A
  • Male pronucleus
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9
Q

What is the ovum nucleus called when it increases in size upon sperm entry?

A

Female pronucleus

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10
Q

What are the cells within the zygote called as their numbers increase?

A

Blastomeres

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11
Q

How many days after fertilization is a morula formed? How many blastomeres in a morula?

A
  • ~3 days post-fertilization
  • Morula seems to have 16 blastomeres, although sources largely conflict
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12
Q

Describe the two types/structures of cells in a blastocyst

A
  • Outer layers of large, squamous trophoblasts
  • Cluster of cells inside called inner cell mass
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13
Q

What will the inner cell mass eventually become?

A

The embryo

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14
Q

What will the trophoblasts eventually become?

A

Placenta and associated blood vessels

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15
Q

Which hormones prepare the endometrium to receive the blastocyst

A
  • Oestrogen
  • Progesterone
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16
Q

How long does implantation into the endometrium take, and when is it finished?

A
  • Takes about 5 days
  • Finished about 12 days after ovulation
17
Q

How do blastocysts prevent menstruation?

A

Trophoblasts secrete hCG to sustain the luteum

18
Q

How many days until a morula is formed?

A

~4

19
Q

How many days until a blastocyst is formed?

A

~5 (1 day after morula)

20
Q

Which layer of the inner cell mass is closer/farther from the endometrium during implantation?

A

Closer: Epiblast
Farther: Hypoblast

21
Q

How is the mesoderm formed?

A
  • Gastrulation
  • Folding of epiblast fold down in, forming the mesoderm
22
Q

Describe the development of the nervous system

A
  • Mesoderm develops into notochord
  • Factors secreted by notochord cause a groove to form in the plate, and the folds gradually become larger until they fuse into a neural tube
23
Q

What structures develop from the neural tube?

A
  • Brain
  • Spinal cord
24
Q

How many days after conception before heartbeat?

A

22

25
Q

How long after conception do primordial germ cells develop?

A

3-4 weeks

26
Q

Where do gametes come from?

A

Endoderm

27
Q

What are factors that cause birth defects called?

A

Teratogens

28
Q

List some environmental factors that can lead to birth defects

A
  • Thalidomide
  • Alcohol
  • Maternal-foetal infections
29
Q

Which systems does teratogen exposure most affect?

A

Systems that are developing quickly.

30
Q

Is teratogen exposure more likely to cause loss of pregnancy defects in early or late pregnancy?

A

Early

31
Q

Are teratogens only chemicals?

A

No. Changes in the maternal environment can also have bad effects, such as maternal fever.

32
Q

How does size at birth influence adult disease?

A

The following are decreased in low birthweight babies:
- Cardiovascular and metabolic disease
- Neurologicla and mental disorders

Some cancers are increased in high birth weight (same for allergy.

33
Q

List some tissues/cells that arise from the ectoderm

A
  • Skin
  • Nervous system
  • Hair
34
Q

List some tissues/cells that arise from the mesoderm

A
  • Blood
  • Muscle
  • Bones
35
Q

List some tissues/cells that arise from the endoderm

A
  • Epithelial lining of organs
  • Gametes

Foundations Of Medicine (98 decks)

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