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embryology (E1 Woods) > The embryonic period > Flashcards

The embryonic period Flashcards

1
Q

what is gastrulation

A

process that establishes the three primary germ layers, forming a trilaminar embryonic disk

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2
Q

define chordoma

A

benign or malignant tumor that arises from remnants of the notochord (found either intracranially or in sacral regions)

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3
Q

what is hCG (human chorionic gonadotropin)

A

glycoprotein hormone that stimulates the production of progesterone by the corpus luteum

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4
Q

what is human placental Lactogen (hPL)

A

protein hormone that induces lipolysis, elevating free fatty acid levels in the mother (growth hormone of the fetus)

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5
Q

how is amniotic fluid reabsorbed?

A

swallowing, absorption through GI tract, or excess is passed into maternal blood

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6
Q

define neurulation

A

formation and closure of the neural tube

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7
Q

what does Hox (Homeobox complex) do?

A

controls the basic segmentation of the human embryo in a craniocaudal direction during the embryonic period

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8
Q

what are the 2 layers in the embryo

A

epiblast & hypoblast

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9
Q

what are the 2 layers in the trophoblast

A

syncytiotrophoblast & cytotrophoblast

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10
Q

what is the extra embryonic (XE) Mesoderm derived from

A

epiblast (& yolk sac)

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11
Q

where is the extra embryonic mesoderm found

A

between the inner lining of the cytotrophoblast and yolk sac

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12
Q

what kind of support does the XE mesoderm give

A

mechanical and trophic

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13
Q

what is the fetal contribution to the placenta

A

chorion

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14
Q

what can a pregnancy ultrasound done in the 1st trimester do:

A 
confirm normal pregnancy
determine the baby's age
look for problems
determine the baby's heart rate
look for multiple pregnancies (i.e. twins)
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15
Q

what major events occur during the embryonic period

A 
all major body systems develop
2D disk to 3D cylinder
Folding of the embryo
Craniocaudal folding-CNS
Lateral Folding-amnion/body wall
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16
Q

what is gastrulation the beginning of

A

morphogenesis

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17
Q

what are the three germ layers

A

endoderm, mesoderm, ectoderm

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18
Q

what is the primitive streak

A

future axis of embryo

19
Q

what are all primary germ layers derived from

20
Q

what is the course for embryonic tissues starting with the fertilized egg

A

fertilized egg-> blastocyst-> inner cell mass
from inner cell mass it can go to either hypoblast or epiblast
hypoblast-> extraembryonic endoderm-> yolk sac (ends here)
epiblast-> either amniotic ectoderm (ends there) or primitive ectoderm
primitive ectoderm-> primitive streak (then to embryonic endoderm and mesoderm) or straight to embryonic ectoderm

21
Q

what is caudal dysplasia

A

Germ layer disorder where there is a total or partial failure of development of the lower vertebrae, including the sacrum, which results in associated abnormalities of the lower extremities, spine, kidneys, GI and Genitourinary tracts

22
Q

what is caudal dysplasia caused by

A

abnormal gastrulation (mesoderm migration is disrupted)

23
Q

what is the primitive streak replaced by

24
Q

what are the functions of the notochord

A

structures- acts as rigid axis around which the embryo develops
skeletal- foundation upon which the vertebral column will form
Forms part of the intervertebral disks
Induction- will bring about formation of the neural tube

25
Q

what does chroma originate from

A

develops from remnants of embryonic notochord

26
Q

what functions as the primary inductor in the early embryo

27
Q

what is Piebaldism

A

disorder characterized by a congenital white forelock and multiple symmetrical hypo pigmented or depigmented areas

28
Q

what is Vitiligo

A

it is a disorder characterized by the loss of melanocytes and is considered an autoimmune disorder

29
Q

what is the forebrain considered at 4 weeks

A

prosencephalon

30
Q

what is the midbrain considered at 4 weeks

A

mesencephalon

31
Q

what is the hindbrain considered at 4 weeks

A

Rhombencephalon

32
Q

what are common characteristics of iniencephaly

A

extreme retroflexion of the head
short and almost absent neck
hyperextended spine
facial skin is connected directly to the skin of the chest; the scalp is directly connected to the skin of the back

33
Q

what is spina bifida

A

failure of neural arches to form

34
Q

what is S.b. occulta

A

archest absent, tube is normal

35
Q

what is S.b. meningocele

A

dura and arachnoid also protude

36
Q

how is it hypothesized that folic acid prevents neural tube defects

A

disorders linked transformation of homocysteine to methionine (increased homocysteine elves appear to prevent the closure of the neural tube)

37
Q

Explain the development of the amnion

A

It is a thin protective membraned that develops from the epiblast
Initially, the amnion overlies only the bilaminar embryonic disk (as the embryo grows it eventually surrounds the entire embryo creating the amniotic cavity)
Then, the amniotic cavity becomes filled with the amniotic fluid
Amniotic fluid protects the developing fetus and can be examined in a procedure (amniocentesis)

38
Q

explain the development of the yolk sac

A

The hypoblast cells migrate and become the exocoelomic membrane
The hypoblast and the exocoelomic membrane form the yolk sac

39
Q

Describe Valamentous Placenta

A

occurs when the umbilical (fetal) blood vessels abnormally travel the amniochorionic membrane before reaching the placenta proper

40
Q

describe Placenta previa

A

occurs when the placenta attaches in the lower part of the uterus, covering the internal os

  • placenta blocks cervical opening
  • classic of 3rd trimester bleeding
41
Q

what are the risk factors for placenta accreta/increta/percreta

A

curettages, previous C-section, severe endometritis, or closely spaced pregnancies

42
Q

describe plreeclampsia and eclampsia

A

preeclampsia= sudden development of maternal hypertension
involves a generalized arteriolar constriction that impacts the brain, kidneys, liver and small blood vessels
treatment involves magnesium sulfate and hydrazine
risk factors: nulliparity, diabetes, hypertension, renal disease, twin gestation, hydatidiform mole
Eclampsia is the same but includes the symptom of convulsions

43
Q

what are the events of neurulation

A
  1. notochord induced the overlying ectoderm to differentiate into the neuroectoderm and form the neural plate
  2. neural plate folds to give rise to the neural tube
  3. as neural plate folds, some cells differentiate into neural crest cells and form column of cells along both sides of the neural tube
  4. the rostral part of the neural tubes become the adult brain
  5. the caudal part of the neural tubes become the adult spinal chord
  6. the lumen of the neural tube gives rise to the ventricular system of the brain and central canal of the spinal cord

embryology (E1 Woods) (3 decks)

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