conception and fetal development (unit 1) Flashcards Preview

OB > conception and fetal development (unit 1) > Flashcards

Flashcards in conception and fetal development (unit 1) Deck (77)
Loading flashcards...
1
Q

conception

A
•union of sperm and egg
•sequential process
1. gamete formation 
2. ovulation
3. fertilization
4. implantation
2
Q

gametogenesis

A
  • gamete formation

* each has 22 autosome and ONE sex chromosome

3
Q

female gametes

A
  • born w/ eggs
  • estrogen in uterine cilia assists the ovum movement to uterine cavity
  • ovulation 14 days prior to next menstrual period
  • ovum viable for 24 hrs
4
Q

male gametes

A
  • continuously produce sperm from puberty
  • few hundred of the millions ejaculated reach ovum
  • only ONE sperm fertilizes
  • flagellum propel sperm toward ovum (4-6 hrs)
  • sperm viable for 2-3 days
5
Q

ovulation

A
  1. pituitary releases FHS to get egg ready
  2. FSH stimulates more estrogen
  3. estrogen stiumlates pit to release LH
  4. LH triggers release of egg (ovulation)
  5. progesterone released in response to ovulation and prepares uterine lining for implantation
  6. if no fertilization, less progesterone release -> menstrual cycle begins
6
Q

fertilization

A
  • takes place in ampulla (outer 3rd of fallopian tube

* journey thru tube to uterus takes 3-4 days

7
Q

sex determination

A

•based on male gamete

  • XX+XX = female
  • XX+XY = male
8
Q

unifactorial (single) gene transmission

A

•dominant vs. recessive

  • autosomal dominant
  • autosomal recessive
  • X-linked
9
Q

multifactoral gene transmission

A

•2 or more genes on different chromosomes affected

10
Q

X-linked dominant transmission

A
  • affected males transmit abnormal gene to daughters ONLY
  • can also be transmitted by heterozygous females
  • Ex: FXS; vit D-resistant rickets
11
Q

fragile X syndrome (FXS)

A

•most common inherited form of mental retardation

12
Q

X-linked recessive transmission

A
  • affected male receives defective gene from carrier mother and transmits abnormal gene ONLY to daughters on X chromosome
  • daughters are usually carries and are affected ONLY if they receive an abnormal gene on the X chromosome from BOTH parents
  • Ex: hemophilia, color blindness, Duchenne muscular dystrophy
13
Q

Turner’s syndrome

A
  • only have one X chromosome
  • affects females only
  • short statue
  • no ovary development
14
Q

Kleinfelter’s syndrom

A
•XXY
•affects males only
•tall/thin
•small testicles
-infertile
-sparse body hair
-slight body build
15
Q

autosomal dominant inheritance

A
  • only one copy of abnormal gene to be affected
  • males and females equally affected
  • no skipping generations
  • Ex: Huntington’s Marfan, Dwarfism
16
Q

autosomal recessive inheritance

A
  • expressed only if there are 2 abnormal genes (homozygotic)
  • parents are carriers and unaffected by faulty gene
  • Ex: PKU, sickle cell, cystic fibrosis
17
Q

autosomal abnormalities

A

•abnormalities of chromosome # or structure

18
Q

abnormalities in chromosome #

A
  • polyploidy- 69 or 92 chromosomes

* aneuploidy- Down syndrome (trisomy 21)- extra chrom. on 21st pair

19
Q

abnormalities in chromosome structure

A
  • translocation- exchange
  • deletion- loss
  • inversion- rearrange
20
Q

implantation

A
  • occurs 6-10 days after conception in upper uterus
  • possible to have spotting
  • implant into endometrium (outer layer)
21
Q

pre-embryonic stage of pregnancy

A
  • conception thru day 14
  • zygote undergoes mitotic cellular division
  • 50% of pregnancies end here and we never know preggo
22
Q

morula/blastocyst

A

•dividing embryonic cellular mass

23
Q

layers of embryo

A
  • ectoderm- upper layer
  • mesoderm- middle layer
  • endoderm- lower layer
24
Q

ectoderm

A

•epidermis, glands, nails & hair, central and peripheral nervous system, lens of the eye, tooth enamel, floor of the amniotic cavity

25
Q

mesoderm

A

•Bones, teeth, muscles (skeletal, smooth, cardiac), dermis, connective tissue, cardiovascular system, spleen, urogenital system

26
Q

endoderm

A

•Lining of the respiratory and digestive tracts, and the glandular cells of associated organs (oropharynx, liver, pancreas, urethra, bladder, and vagina), and the roof of the yolk sac

27
Q

membranes around embryo

A
  • begin to form once implanted
  • amnion
  • chorion
28
Q

chorion

A
  • contains chorionic villi

* becomes covering of fetal side of placenta

29
Q

amnion

A
  • inner cell membrane
  • developing embryo draws amnion around itself forming fluid sac
  • covers umbilical cord
30
Q

amniotic fluid functions (4)

A
•cushions 
•maintains temperature
•provides nutrients/waste disposal
•keeps membrane away from developing fetus
-provides freedom of growth movement
31
Q

embryonic stage of development

A
  • beginning of week 3 thru end of week 7
  • major body organs formed
  • differentiation begins
  • cephalocaudal (head to toe)
  • central to peripheral (inside to outside)
32
Q

teratogens during embryonic stage

A

•embryo extremely vulnerable
•all or nothing effect
*this is before mom misses period, so may not realize exposing an embryo

33
Q

week 3 pregnancy

A
  • 1st missed period
  • fetal CNS development (neural groove)
  • early heart development
  • primitive blood cells
34
Q

week 4 pregnancy

A
•embryo C-shape
•neural tube forming
•face, upper resp. tract forming
•upper extremity buds
•partitioning of heart begins
•HB at 17-18 days
*earliest functioning system
35
Q

week 5

A
  • large head
  • heart 4 chambers
  • paddle shaped limbs w/ notches b/t fingers
  • lower limbs less differentiated
36
Q

week 6

A
  • heart finishes formation
  • more defined extremities
  • facial, eye, ear development
37
Q

neural tube

A
  • structure that becomes brain and spinal cord
  • requires folic acids
  • development interference can result in defects (ex: spin bifida)
38
Q

week 7

A
  • continued growth/refinement of organs
  • face more human
  • intestines OUTSIDE abdominal cavity
  • sex diff. begins
39
Q

8 weeks

A
  • eyes, ear, nose recognize
  • s. intestine coils in um. cord
  • ossification begins
  • fetus begins moving
  • heart/lung cavities forming
  • external genitalia forming
  • brain development begins
  • spinal cord lengthens
40
Q

fetal stage of pregnancy

A
  • beginning of week 8 thru delivery
  • all major organ systems present
  • continued growth/refinement
41
Q

teratogens during fetal stage

A
  • can still cause CNS damage

* less likely to cause structural abnormalities

42
Q

weeks 9-12

A
  • fetal movement begins (undetectable)
  • body grows faster than head
  • intestines into abd. cavity
  • blood formation in liver, then spleen
  • produce urine
  • fetal sex can be determined by autopsy
43
Q

weeks 13-16

A
  • rapid growth in length

* female has lifetime egg supply

44
Q

16 weeks

A
  • 5.5 inches tall; 6 oz
  • brows, lashes, hair
  • grasp, kick, somersault
  • finger/footprints
  • maybe determine sex w/ u/s
45
Q

weeks 17-20

A
•quickening begins
•vernix caseosa
•lanugo
•brows/head hair
•swallow amniotic fld
•produce own insulin
*best time to do u/s
46
Q

quickening

A

•start to feel fetal movement

47
Q

vernix caseosa

A

•greasy deposit covering skin of baby at birth

48
Q

lanugo

A

•fine soft hair

49
Q

weeks 21-24

A
  • 8”-9”; 1.5 lbs
  • lungs produce surfactant
  • capillary network around alveoli
50
Q

24 weeks

A
  • respond to sound
  • distinguish taste
  • react to temp
51
Q

28 weeks

A
•3 lbs
•storage of brown fat
•eyelids un-fused (can see)
•longer scalp hair
•cerebral fissures
•weak suck, cry
*good chance of survival
52
Q

brown fat

A
  • unique source of heat for neonates
  • around kidneys, neck, and b/t scapulae
  • present for several weeks after birth
53
Q

weeks 29-32

A
  • 12”; 3.75 lbs
  • finger/toenails extend
  • subcutaneous fat deposited
  • skin pigmented, pink, smooth
  • surfactant increase
  • may favor head-down position
54
Q

lecithin (L)

A
  • alveoloar surfactant required for post-natal lung expansion
  • detectable @ 21 weeks
  • increases after 24 weeks
55
Q

sphingomvelin (S)

A
  • pulmonary phospholipid

* remains constant in amnt

56
Q

L/S ratio

A
  • 2:1 indicates mature

* measured in amniotic fld

57
Q

40 weeks

A
  • 18-21”; 7.5 lbs
  • good muscle tone
  • myelination of brain
  • sleep-wake cycle
  • strong suck reflex
  • testes/labia majora developed
58
Q

placenta formation

A
  • arises from Chorion
  • implants into decidualized layer of uterus
  • maternal spiral arteries adjust to accommodate blood flow
59
Q

placenta gas exchange

A
  • maternal and fetal circulation not directly attached to each other
  • gas exchange occurs at lacunae areas b/t spiral arteries and fetal villi
60
Q

fetal side of placenta

A

•placental arteries/veins converge into 2 placental arteries and 1 vein of umbilical cord

61
Q

maternal side of placenta

A
  • rough

* not covered with amnion

62
Q

placental circulation supporting fetus

A
  • completely by week 12

* placental malformations can result in miscarriage

63
Q

post-conception

A
  • ovary secretes progesterone from corpus luteum for 12 weeks prior to placenta taking over
  • inadequate progesterone results in miscarriage
  • ovulation also ceases
64
Q

fetal gas exchange

A
  • umbilical vein carries O2 blood and nutrients to fetus from placenta
  • umbilical arteries carry CO2 wastes from fetus to placenta
65
Q

fetal PO2

A
•~30 mmHg
•fetus tolerates low PO2 b/c
-higher Hgb and hct
-high O2 carrying capacity of fetal Hgb
-fetal HR 110-160 bpm
66
Q

placental metabolic fxns

A
  • gas exchange
  • nutrient transfer (glucose major)
  • waste removal
  • antibody transfer
  • maternal hormone transfer
67
Q

good antibody transfer

A

•IgM
•protects infant 1st 2 months of life
•continued 3-6 months if breast fed
*baby immune to what immune to

68
Q

bad antibody transfer

A

•Rh isoimmunization

69
Q

estrogen fxn

A

•stimulates uterine growth

70
Q

progesterone fxn

A
  • maintains uterine lining to prevent miscarriage
  • relaxes smooth muscle to prevent ctxn
  • induces labor
71
Q

human placental lactogen (hPL)

A
  • growth hormone that stimulates mom’s metabolism to supply baby w/ glucose
  • stimulates breast development
72
Q

human chorionic gonadotropin (hCG) fxn

A
  • produced by placenta following implantation
  • detected 8-10 days post-conception
  • preggo test positive
73
Q

monozygotic twins

A
  • identical
  • 1 egg, 1 sperm
  • same sex/genotype
74
Q

dichorionic diamniotic

A

*division shortly after fertilization
•2 amnions
•2 chorions
•2 placentas

75
Q

monochorionic diamniotic

A

*division 4-8 days after fertilization
•2 amnions
•1 chorion
•1 placenta

76
Q

monochorionid monoamniotic

A
*division 8+ days after fertilization 
•1 amnion
•1 chorion
•1 placenta 
*conjoined twins
77
Q

dizygotic twins

A
  • fraternal
  • 2 eggs, 2 sperm
  • may be different sexes
  • 2 amnions, 2 chorions, 2 placentas
  • different genotype