Embryonic Development (lecture) Flashcards

1
Q

What is fertilization?

A
  • When nucleus of sperm enters egg
  • acrosome: acrosomal enzyme breaks down zona pellucida of egg
  • fertilization membrane -> no longer penetrable
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2
Q

What is a blastocyst

A
  • form of the egg that gets implanted
  • human chorionic gonadotropin
    • released when implanted
  • Fx: maintains corpus luteum: maintains uterine lining
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3
Q

What is the outer layer of a blastocyst?

A

Trophoblast
- becomes placenta

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4
Q

What is the inner portion of a blastocyst?

A

Inner cell blast
- becomes embryo
- totipotent stem cells

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5
Q

What is implantation?

A

Trophoblast cells invade endometrium -> form chorionic villi -> become chorion -> placenta

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6
Q

What is placenta previa?

A

Placenta blocking the cervix. Requires c-section birth

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7
Q

What is different with fetal blood circulation?

A

Diverts blood away from lungs since there is no breathing yet

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8
Q

Functions of ductus arteriosus and foramen ovale of the atria. What do they develop into outside of the womb?

A

Ductus arteriosus: Bypasses pulmonary circuit to the aorta. Connects the aorta and pulmonary trunk. becomes ligamentum arteriosus

Foramen Ovale of the Atria: Shunts blood from the R. atria to the L. atria. Develops into fossa ovale

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9
Q

Where does the umbilical vein go to?

A

Through liver into IVC

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10
Q

Where does the umbilical artery go to?

A

Internal iliac arteries

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11
Q

What is gastrolation

A

inner cell mass forms 3 primary germ layers:

  1. ectoderm
  2. mesoderm
  3. endoderm
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12
Q

Amnion

A
  • contains amnionic fluid. ruptures during labor (“water breaking”)
  • amniocentesis; allows genetic testing for baby
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13
Q

What is ontogeny recapitulates phylogeny?

A
  • embryonic development proves evolution
  • all vertebrates look identical in early stages of development
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14
Q

Organogenesis

A

Two major processes:

  1. morphogenesis: formation of 3D shape of organ
  2. Differentiation: specialization of stem cells to differentiated cells
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15
Q

How does organogenesis occur?

A

Through localization signals
1. chemical gradient
2. induction: physical contact between cells

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16
Q

Induction of chicken teeth

A

e.g. injected mouse mesoderm cells into chicken embryo = induced chicken teeth

17
Q

What is neurulation?

A

Example of induction
Process of nervous system formation. Complete after 18 yo

18
Q

What is spina bifida?

A

neural tube doesn’t close posteriorly. results in paralysis from waist down

19
Q

What is ancephaly?

A

Neural tube doesn’t close anteriorly. Results in no brain formation - ends at brainstem

20
Q

Describe the formation of neural crests

A
  • PNS
  • melanocytes
21
Q

What are Mongolian spots?

A

collection of crest cells at buttocks
- common in Asian babies

22
Q

What is a unique structure identified in 4-week-old embryos?

A

Branchial Arches
- make gills in fish
- make bones in humans

23
Q

Somites

A

become vertebrae and other repeating structures

24
Q

Limb bud

A

from chemical gradient and conduction

25
Limb development
- controlled apoptosis between fingers - incorrect development causes webbing between fingers
26
When does a human embryo become a fetus?
Week 10
27
Facial development
morphological movement
28
Fetal alcohol syndrome
- Drinking alcohol during first 10 weeks of development Sx: mental handicap Signs: - eyes far apart - flat nose bridge - no philtrum - wide mouth
29
Cleft lip/ cleft palate
2 maxilla or palatine bone don't meet in the middle
30
Reproductive structure development
starts at six weeks -external genitalia
31
What is hypospadias?
urethra doesn't form in middle of penis
32
Childbirth
- 40 weeks total - mother's Neurohypophysis (PPG) makes oxytocin - oxytocin is on a positive feedback loop
33
What is the role of oxytocin during childbirth?
- causes contractions of smooth muscle of the uterus Labor Function: 1. cervical dilation 2. baby expulsion 3. placenta expulsion
34
Indication for cesarean section birth
- transverse/breeched presentation - placenta abruptio - placenta previa
35
What is situs inversus?
Organs develop mirrored flipped