Week 2 Embryology 3 Flashcards

1
Q

Placenta

A

Part from chorion, part from mom
Temporary organ
Forms when trophoblast form the chorion (3 layers)
Will develop extensions (villi)
Transfer of substances between maternal and fetal systems

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2
Q

2 Components of the placenta

A
  1. Embryonic (chorion frondosum)

2. Maternal (decidua basalis) components

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3
Q

Embryonic component of placenta

A

Chorion frondosum

specific part of chorion

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4
Q

Maternal component of placenta

A

Decidua basalis

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5
Q

What two parts make up placenta

A

Chorion frondosum and decidua basalis

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6
Q

3 Parts of Decidua

A
  1. Decidua basalis - portion of endometrium underlying the implantation site
  2. Decidua capsularis - portion overlying the implanted embryo and separating it from the uterine cavity
  3. Decidua parietalis - the remainder of the endometrium
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7
Q

Decidua basalis

A

Maternal component placenta

Portion of endometrium underlying the implantation site

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8
Q

Decidua capsularis

A

Maternal component placenta
Portion overlying the implanted embryo and separating it from the uterine cavity

Is eventually lost as the amniotic cavity enlarges and occupies all space in the uterine cavity

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9
Q

Decidua parietalis

A

Maternal component placenta

The remainder of the endometrium

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10
Q

Muscle of uterus

A

Myometrium

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11
Q

OS

A

opening

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12
Q

Chorion Fondosum

A

Chorionic plate
Area where villi develop (villious chorion)
Villi are the agents of exchange between maternal and fetal systems
Fetal surface of placenta should have chorionic (fetal) blood vessels

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13
Q

Villious Chorion

A

Villi of the placenta

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14
Q

Chorion fondosum villi

A

Villi are the agents of exchange between maternal and fetal systems
Fetal surface of placenta should have chorionic (fetal) blood vessels

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15
Q

Region in contact with decidua basalis

A

Chorion frondosum

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16
Q

Placental vessels come from

A

Chorionic villi

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17
Q

Function of chorionic villi

A
  • Oxygen and nutrients in the maternal blood in the intervillous spaces diffuse through the walls of the villi and enter the fetal capillaries
  • Carbon dioxide and waste products diffuse from blood in the fetal capillaries through the walls of the villi to the maternal blood in the intervillous spaces.
  • Need lots of surface area but thin walls
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18
Q

Structure of Primary chorionic villi

A

Solid outgrowths of cytotrophoblast that protrude into the syncytiotrophoblast

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19
Q

Structure of Secondary chorionic villi

A

Have a core of loose connective tissue which grows into the primary villi about the third week of development

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20
Q

Structrue of Tertiary chorionic villi

A

Contain embryonic blood vessels

These blood vessels connect up with vessels that develop in the chorion and connecting stalk and begin to circulate embryonic blood about the third week of development

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21
Q

Avg day for heart beat

A

21 days

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22
Q

4 parts of placental barrier

A
  1. syncytiotrophoblast
  2. cytotrophoblast
  3. extraembryonic mesenchyme
  4. fetal endothelium
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23
Q

Fetal endothelium

A

Single layered wall of fetal capillaries

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24
Q

Placental Membrane

A

Not a strict barrier
Variety of substances cross freely (not all good)
Beneficial or harmful
Some substances do not cross

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25
Q

Beneficial substances that cross the placenta

A

O2, CO2, glucose, free fatty acid, vitamins

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26
Q

Harmful substances that cross the placenta

A

Rubella, measles, herpes, cytomegalovirus, varicella, poliomyelitis
Cat X drugs: thalidomide, warfarin, nicotine, alcohol
Cat D drugs: some abx, valium, librium, xanax

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27
Q

Category X drugs

A

Thalidomide, warfarin (warfarin syndrome), isotretinoin, nicotine, alcohol, phenytoin

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28
Q

Category D drugs

A

Some antibiotics, valium, librium, xanax, lithium

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29
Q

Erythroblastosis fetalis

A

Rh factor
Rh-negative mother with Rh-positive fetus will produce antibodies
1st pregnancy unaffected
Antibodies in 2nd pregnancy with Rh-positive fetus
Destruction of fetal RBCs
Brain damage to fetus and severe edema (hydrops fetalis)

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30
Q

Symptoms in newborn of erythroblastosis fetalis

A
Anemia
Edema
Enlarged liver or spleen
Hydrops
Newborn jaundice
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31
Q

Edema

A

swelling under the surface of the skin

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32
Q

Hydrops

A

Fluid throughout the body’s tissues, including in the spaces containing the lungs, heart and abdominal organs
*left untreated can be fatal

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33
Q

Erythroblastosis fetalis Treatment

A

RhoGAM (shot given that prevents the antibodies from developing)
Human immunoglobin with antibodies against the Rh Factor
Prevents maternal antibody response to Rh-positive cells for the fetus

34
Q

Cotyledons

A

Clumps of villi

Dr counts these, usually between 12 and 15. If find 9, probably some inside still

35
Q

Chorionic Villus Sampling

A

Test for familial genetic disorders, advanced maternal age (chromosomal abnormalities)

Can be done earlier in pregnancy (10-12 weeks) than amniocentesis (15-20 weeks)

36
Q

Weeks for Chorionic Villus Sampling

A

10-12 weeks

37
Q

Weeks for Amniocentesis

A

15-20 weeks

38
Q

Umbilical Vein

A

Only one! Ones get reabsorbed.
Oxygen, nutrients and hormones delivered to the baby

OPPOSITE from normal

39
Q

Umbilical Arteries

A

Wastes and carbon dioxide delivered from the baby
Full of CO2, not O2

OPPOSITE from normal

40
Q

Wharton’s Jelly

A

Gelatinous connective tissue in the placental cord
Increases in volume at birth to assist in closure of placental blood vessels
Matrix cells have recently been identified as a potential source of stem cells
Can bank this cord blood

41
Q

Why is there one umbilical vein?

A

During development, there are two that drain blood from the placenta to the heart
The R umbilical vein regresses and under normal circumstances is completely obliterated during 2nd month of development
L umbilical vein persists and delivers blood from the placenta to the developing fetus

42
Q

Which umbilical vein persists?

A

Left

43
Q

Umbilical vessels

A

Radiating to form chorionic vessels

44
Q

Normal attachment of cord is

A

Usually off middle

45
Q

Bilobed

A

2 lobes to placenta

46
Q

Circumvallate

A

Cord off the edge of placenta

47
Q

Succenturinate

A

Extra cord off the placenta

48
Q

Velamentous

A

ONLY one that is a real problem

The fetal (or umbilical) blood vessels travel abnormally
Pass through amniochorionic membrane before reaching the placenta
These vessels are more exposed to trauma during the birth process
Knots in cord, can be prolapsed during delivery

49
Q

3 Locations where placenta implants

A
  1. Posterior - back
  2. Anterior - front
  3. Fundal - top

All 3 are fine!

50
Q

Placenta Previa

A

Implantation of the placenta over the cervical os

-as baby gets bigger, puts pressure on cord, prone to maternal bleeding and problems

51
Q

Placenta Accreta

A

Abnormal trophoblastic invasion into the muscular layer of the uerus (placenta increta) or through the uterine wall and into the surrounding tissues (placenta percerta)

52
Q

Partial placenta previa

A

Covers part of the cervical opening

53
Q

Placenta Accreta

A

The placental roots grow too deeply into the muscular wall of the uterus

54
Q

Placenta Increta

A

The placenta invades through the muscle of the uterus

55
Q

Placenta Percreta

A

The placenta pushes through the uterine wall and invades other organs, like the bladder
Similar to ectopic, potential surgical

56
Q

Placenta as an endocrine organ

A
  • Synthesizes glycogen, cholesterol and fatty acids
  • Nutrients, oxygen, some immunoglobulins
  • Removes waste products
  • Synthesis and release of hormones Ex. hCG
  • Most synthesized in the syncytiontrophoblast
  • hCG - stimulates production of progesterone by the ovary (corpus luteum)
57
Q

hCG

A

Tells ovary to keep making estrogen and progesterone until placenta can make its own

58
Q

Hormones that placenta makes

A
Chorionic somatomammotropin
Human placental lactogen (hPL)
induces lipolysis, elevating free fatty acids in mother
"growth hormone" of the fetus
Progesterone
Estrogens
59
Q

Progesterone

A

Steroid hormone that maintains the endometrial lining during pregnancy, also suppresses contractility in uterine smooth muscle

60
Q

Estrogens

A

Steroid hormones, stimulate mammary gland development

61
Q

Placental calcification

A

Sign of placental aging. Past 40 weeks is a post date pregnancy
The pattern of calcification is similar to that seen in other aging tissues
Probably a response to cell death and diminished blood circulation in localized regions of the placents
One significant risk factor - smoking

62
Q

One significant risk factor for placental calcification

A

Smoking

63
Q

Lithopedion

A

Fetal death usually with an ectopic pregnancy.

Fetus too large to be reabsorbed by the body and calcifies.

64
Q

Function of Amniotic Fluid

A
  • Permits symmetrical external growth
  • Enables fetus to move freely
  • Acts as a barrier to infection
  • Permits normal fetal lung development
  • Prevents adherence of amnion to embryo/fetus (amniotic band syndrome)
  • Helps maintain homeostasis (temp, fluids, electrolytes)
65
Q

Oligohydramnios

A

Too little fluid
Not enough space for baby to move
Limb defects, can’t practice breathing = don’t grow correctly
Associated with renal agenesis and obstructive uropathy
Potter syndrome - fatal

66
Q

Potter Syndrome

A

Fatal
Renal agenesis
Lungs don’t develop
Baby is compressed and have flattened face, frog legs

67
Q

Pulmonary hypoplasia

A

For normal development amniotic fluid must be brought into the lung by fetal breathing movements, leading to distension of the developing lung

68
Q

Polyhydramnios

A

High volume of amniotic fluid
Associated with CNS anomalies and esophageal atresia
Possible tube blockage, usually in esophagus and fetus is trying to swallow but can’t. Possible there is no reflex in brain to swallow, not a good outcome

69
Q

Amniotic Band Syndrome

A

Tears in the amnion detach and surround fetus
Or adhesions between the amnion and affected structures
May cause ring constrictions or amputations of limbs or digits

70
Q

2 ways blood vessels form

A
  1. Vasculogenesis

2. Angiogenesis

71
Q

Vasculogenesis

A

One way blood vessels form

*Blood vessels arise from coalescence of hemangioblasts, which arise from blood islands

72
Q

Angiogenesis

A

One way blood vessels form

*Vessel formation via branches from existing vessels

73
Q

Major vessels form via

A

Vasculogenesis

74
Q

Early vasculogenesis

A

Splanchnic layer covering yolk sac

*early in development this occurs in yolk sac, one of few things use yolk sac

75
Q

AGM

A

Aorta-gonad-mesonephros region

76
Q

Definitive hematopoietic stem cells

AGM

A

Formation of blood cells in yolk sac is transitory
Definitive hematopoietic cells arise from mesoderm around the aorta
These cells will colonize the liver

77
Q

Hematopoietic tissue in the fetus

A

Stem cells colonize the liver - the major hematopoietic organ of the fetus
Later stem cells from the liver colonize the spleen, thymus and ultimately the bone marrow

78
Q

Major hematopoietic organ of the fetus

A

Liver

79
Q

Fetal hemoglobin’s affinity for O2

A

Higher affinity for O2

80
Q

Thalassemia syndromes

A

Group of inherited blood disorders
Abnormal form of hemoglobin, the protein in red blood cells that carries oxygen
Results in excessive destruction of red blood cells and anemia