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Foundations Exam > embryo and human health > Flashcards

embryo and human health Flashcards

1
Q

What is fertilization

A

The process by which two haploid sex cells fuse to form a diploid cell (now called a zygote)

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2
Q

T/F: fertilization is series of events (a process), rather than a single event

A

True

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3
Q

Requirements for succesful fertilization:

A
  1. Mature, fully motile sperm
  2. Unobstructed female reproductive tract
    3.Both sperm and secondary oocyte are still viable
  3. capacitation: final stage of maturation that happens in the isthmus of the uterine tube
  4. acrosome reactin
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4
Q

Where and when do sperm undergo capacitation

A

Inside the uterine tube, spermatazoa bind to the epithelium of the isthmus for 24 hours

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5
Q

What prohibits premature capacitation

A

cholesterol. Cholesterol is removed from the surface of the sperm head AFTER it undergoes capacitation .

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6
Q

What has to happen in order to initate the acrosome reaction

A

glycoproteins deposited on the sperm head in the epidymis are removed

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7
Q

What factors help move the sperm to the ampullae

A

muscular contractions, chemo attractants, and thermal gradient

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8
Q

What exactly allows the egg to move down the tube and the sperm to move up?

A

compartmentalized contractions, one area moving in isolation

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9
Q

T/F only capacitate sperm seem to be able to respond to chemical and thermal stimuli

A

true.
also, sperm are usually viable in female reproductive tract for 80 hrs.

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10
Q

What allows the sperm to penetrate the corona radiate and reach the zona pellucida.

A

The ICM has lots of hyaluronic acid, the sperm head contains hyaluranidase which breaks down the hyaluronic acid.

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11
Q

When does sperm undergo the acrosome reaction

A

after penetrating the corona radiata, the spermatozoa binds to the zona pellucida.

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12
Q

What prevents other sperm from binding to the egg after one has already fused

A

the change in membrane potential

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13
Q

What is the zona reaction

A

secretory products of cortical granules hydrolyze sperm receptor molecules in the zona. the zona reaction eliminates the ability of other sperm to adhere to the zona

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14
Q

At the 8 cell stage, the zygote undergoes a process called _______

A

compaction: cells in outer areas adhere to each other tightly through gap and tight junctions.
E-cadherin plays a big role in this
The result of compaction is that these cells become organized into an epithelium.

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15
Q

16 cell stage is called the

A

morula

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16
Q

what is the blastocyst

A

a fluid filled cavity that separates the inner cells from the outer epithelium

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17
Q

morula forms _____ days after fertilization
blastocyst forms ______ days after fertilization

A

Morula: 3-4 days
blastocyst: 5-6 days

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18
Q

Explain these three terms together

embryoblast, trophoblast, blastocyst

A

The inner cell mass of a blastocyst is called the embryoblast and the outer layer is called the trophoblast.

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19
Q

The embryoblast forms what structures

A

embryonic and extraembryonic

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20
Q

The trophoblast form ______ structures

A

ONLY EXTRAembryonic structures (placenta)

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21
Q

What is the blastocyst cavity

A

fluid filled space in between the trophoblast and embryoblast

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22
Q

In one sentence, what happens during week 1

A

blastocyst implants into functional layer of the endometrium.

adhesion molecules, especially INTEGRINS, faciliate implantation into the uterine lining

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23
Q

During week 2, the outer trophoblast differentiates into ____ parts

A

2 parts (think week 2)
the outer cellular layer= trophoblast
cells surrounding the inner cell mass fuse= syncytium

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24
Q

How do nutrients from maternal blood cross over into the developing embryo?

A

Via the syncytiotrophoblast.
-these cells penetrate into the uterine lining, the projections will contact maternal vessels and create blood filled lacunae (little lakes)
trophoblast projections will enter the lakes and form junctions with blood vessel epithelial cells and this is how nutrients from mom cross over into embro**

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25
Q

What produces hCG

A

synccytitrophblast

26
Q

In week ____, the bilaminar germ disc form

A

Week 2
Cells of the inner cell mass become epithelialized and separate into two layers
upper layer= epiblast
lower layer= hypoblast

27
Q

the bilaminar germ disc is surrounded by the

A

trophoblast

28
Q

Epiblast cells form the ______

A

amniotic membrane and cavitation results in amniotic cavity

29
Q

Hypoblast is also called the _________

A

primitive endoderm.

30
Q

The yolk sac forms in ______

A

week 2

31
Q

The primary yolk sac is formed by _______

A

hypoblast cells lining the blastocyst cavity

32
Q

The new cavity outside the yolk sac, chorionic cavity, is created by the _______

A

extraembryonic mesoderm

33
Q

the secondary yolk sac (aka definitive yolk sac) is formed by

A

a second wave of hypoblast cells that migrate
-the membrane closes off an pinchess of the primary yolk sac

34
Q

Give a summary of the second week

A
  1. Trophoblast differentiates into two layers (cytotrophoblast and syncytiotrophoblast)
  2. Embryoblast differentiates into two germinal layers (epiblast and hypoblast)
    Epiblast= becomes entire embryo
    hypoblast= forms extraembryonic mesoderm and yolk sac
  3. Two cavities form on either side of the bilaminar germinal disc (amniotic cavity and yolk sac)
35
Q

define totipotent, pluripotent, multipotent, oligpotent

A

totipotent: All powerful, cells that have potential to become anything

pluripotent: Can become any of the 3 germ layers (cant become trophoblast or structures outside the epiblast)

multipotent: can develop into more than one cell type (adult stem cells)

oligopotent: Differentiate into a limited subset of cells

36
Q

In what week does the primitive streak appear

A

week 3

37
Q

What is the primitive streak

A

a condensation of cells migrating to the midline in the posterior area of embryo.
Begins: tail end of disc
progresses about halfway up towards cranial end

38
Q

Why is the primitive streak important

A

can define cranial and caudal ends, right and left, top and bottom aspect to the disc for the very first time

39
Q

Describe epiblast cell migration and gastrulation

A

these cells form characteristics of mesenchymal cells which is what allows them to migrate
-some cells migrate to the primitive streak (nothing speical)
-Some cells detach, invaginate, and replace the hypoblast=FORMING THE ENDODERM
-Some cells migrate further and differentiate to become the mesoderm.

40
Q

Once the 3 germ layers are established (endoderm, mesoderm, and ectoderm) these cells are no longer ________

A

no longer pluripotent
*now you have 3 layers of multipotent cells forming our trilaminar germ disc

41
Q

Endoderm cells give rise to

A

-liver
-gall bladder
-thymus
-thyroid
-parathyroid glands
-tonsils
-epithelial lining of respiratory
-GI and urinary
-auditory tube
-tympanic cavity
Think everything INSIDE= ENDO

42
Q

Mesoderm gives rise to

A

Think: the one trying to get a date
-muscle
-ct
-dermic
-adrenal cortex
-heart
-kidneys
-spleen
-internal repro organs

43
Q

Ectoderm gives rise to

A

Epidermis and its derivates
nervous system
enamel
adrenal medulla
pit. gland
lens of eye

44
Q

Ectoderm gives rise to

A

Epidermis and its derivates
nervous system
enamel
adrenal medulla
pit. gland
lens of eye

45
Q

Which germ layer contributes to the formation of the notochord

A

the mesoderm

46
Q

What induces the development of the neural plate?

A

the notochord

47
Q

The notochord also stimulates the differentiation of other types of mesoderm. The paraxial mesoderm, will further differntiate into structures called _______

A

somites

48
Q

Paraxial mesoderm will

A

-form a series of structures called somites
-eventually form most of the axial skeleton

49
Q

Somites are formed from the ______ mesoderm

A

paraxial.

50
Q

Somites will subdivide into 3 parts. What are they

A
  1. mytomes = develop into muscle
  2. dermotomes= develop into dermis
  3. sclerotomes= develop into skeletal elements
51
Q

Break down myotomes even farther. What will you find?

A

Two components
1. Dorsal epimere = gives rise to deep back muscles
2. ventral hypomere = muscles that move the upper limb and ribs

52
Q

______ join with _______ mesoderm to produce dermis

A

dermatome wil merge with the somatopleure which completes the epidermis and dermis`

53
Q

Intermediate mesoderm will form most of the

A

urinary and reproductive tracts

54
Q

lateral plate mesoderm near the ectoderm=
combined layer of the somatic mesoderm and the ectoderm=
lateral plate mesoderm near the endoderm=

A

near ectoderm= somatic mesoderm
combined middle layer= somatopleure (soma means body)
near endoderm: splanchnic mesoderm

55
Q

Folding of the embryonic disc happens during week ___

A

Week 4.
1. Cranial-caudal folding= head and tail closer together ventrally
2. lateral folding = two edges of the disc together

56
Q

Where is the notochord located on the embryo?

A

dorsal aspect of the embryo

57
Q

What is the vitelline duct

A

it is the connection as a result of laterally folding bringing the two edges of the disc together. The yolk sac pinches off and you are left with a narrow connection between the developing gut tube and yolk sac.

58
Q

Intraembryonic coelom forms _____

A

future body cavities

59
Q

body wall is formed from _______ and ______

A

somatic mesoderm and ectoderm

60
Q

gut tube formed from ______ and _______

A

splanchnic mesoderm and endoderm

61
Q

The primitive streak disappears by the end of the _____ week

A

end of the 4th week

62
Q

Overall summary of embryo
week 2:
week 3:
week 3-4:
Week 4:

A

Week 2: bilaminar embryonic disc forms “week of twos”
Week 3: primitive streak, gastrulation (3 germ layers), trilaminar embryonic disc
Week 3-4 notochord development, neurulation (development of the nervous system)
week 4: craniocaudal and lateral folding of embryo, regression of primitive streak.

Foundations Exam (5 decks)

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