conception and fetal development (unit 1) 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
- pituitary releases FHS to get egg ready
- FSH stimulates more estrogen
- estrogen stiumlates pit to release LH
- LH triggers release of egg (ovulation)
- progesterone released in response to ovulation and prepares uterine lining for implantation
- 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
mesoderm
•Bones, teeth, muscles (skeletal, smooth, cardiac), dermis, connective tissue, cardiovascular system, spleen, urogenital system
26
endoderm
•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
membranes around embryo
* begin to form once implanted
* amnion
* chorion
28
chorion
* contains chorionic villi
| * becomes covering of fetal side of placenta
29
amnion
* inner cell membrane
* developing embryo draws amnion around itself forming fluid sac
* covers umbilical cord
30
amniotic fluid functions (4)
```
•cushions
•maintains temperature
•provides nutrients/waste disposal
•keeps membrane away from developing fetus
-provides freedom of growth movement
```
31
embryonic stage of development
* 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
teratogens during embryonic stage
•embryo extremely vulnerable
•all or nothing effect
*this is before mom misses period, so may not realize exposing an embryo
33
week 3 pregnancy
* 1st missed period
* fetal CNS development (neural groove)
* early heart development
* primitive blood cells
34
week 4 pregnancy
```
•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
week 5
* large head
* heart 4 chambers
* paddle shaped limbs w/ notches b/t fingers
* lower limbs less differentiated
36
week 6
* heart finishes formation
* more defined extremities
* facial, eye, ear development
37
neural tube
* structure that becomes brain and spinal cord
* requires folic acids
* development interference can result in defects (ex: spin bifida)
38
week 7
* continued growth/refinement of organs
* face more human
* intestines OUTSIDE abdominal cavity
* sex diff. begins
39
8 weeks
* 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
fetal stage of pregnancy
* beginning of week 8 thru delivery
* all major organ systems present
* continued growth/refinement
41
teratogens during fetal stage
* can still cause CNS damage
| * less likely to cause structural abnormalities
42
weeks 9-12
* 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
weeks 13-16
* rapid growth in length
| * female has lifetime egg supply
44
16 weeks
* 5.5 inches tall; 6 oz
* brows, lashes, hair
* grasp, kick, somersault
* finger/footprints
* maybe determine sex w/ u/s
45
weeks 17-20
```
•quickening begins
•vernix caseosa
•lanugo
•brows/head hair
•swallow amniotic fld
•produce own insulin
*best time to do u/s
```
46
quickening
•start to feel fetal movement
47
vernix caseosa
•greasy deposit covering skin of baby at birth
48
lanugo
•fine soft hair
49
weeks 21-24
* 8"-9"; 1.5 lbs
* lungs produce surfactant
* capillary network around alveoli
50
24 weeks
* respond to sound
* distinguish taste
* react to temp
51
28 weeks
```
•3 lbs
•storage of brown fat
•eyelids un-fused (can see)
•longer scalp hair
•cerebral fissures
•weak suck, cry
*good chance of survival
```
52
brown fat
* unique source of heat for neonates
* around kidneys, neck, and b/t scapulae
* present for several weeks after birth
53
weeks 29-32
* 12"; 3.75 lbs
* finger/toenails extend
* subcutaneous fat deposited
* skin pigmented, pink, smooth
* surfactant increase
* may favor head-down position
54
lecithin (L)
* alveoloar surfactant required for post-natal lung expansion
* detectable @ 21 weeks
* increases after 24 weeks
55
sphingomvelin (S)
* pulmonary phospholipid
| * remains constant in amnt
56
L/S ratio
* 2:1 indicates mature
| * measured in amniotic fld
57
40 weeks
* 18-21"; 7.5 lbs
* good muscle tone
* myelination of brain
* sleep-wake cycle
* strong suck reflex
* testes/labia majora developed
58
placenta formation
* arises from Chorion
* implants into decidualized layer of uterus
* maternal spiral arteries adjust to accommodate blood flow
59
placenta gas exchange
* maternal and fetal circulation not directly attached to each other
* gas exchange occurs at lacunae areas b/t spiral arteries and fetal villi
60
fetal side of placenta
•placental arteries/veins converge into 2 placental arteries and 1 vein of umbilical cord
61
maternal side of placenta
* rough
| * not covered with amnion
62
placental circulation supporting fetus
* completely by week 12
| * placental malformations can result in miscarriage
63
post-conception
* ovary secretes progesterone from corpus luteum for 12 weeks prior to placenta taking over
* inadequate progesterone results in miscarriage
* ovulation also ceases
64
fetal gas exchange
* umbilical vein carries O2 blood and nutrients to fetus from placenta
* umbilical arteries carry CO2 wastes from fetus to placenta
65
fetal PO2
```
•~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
placental metabolic fxns
* gas exchange
* nutrient transfer (glucose major)
* waste removal
* antibody transfer
* maternal hormone transfer
67
good antibody transfer
•IgM
•protects infant 1st 2 months of life
•continued 3-6 months if breast fed
*baby immune to what immune to
68
bad antibody transfer
•Rh isoimmunization
69
estrogen fxn
•stimulates uterine growth
70
progesterone fxn
* maintains uterine lining to prevent miscarriage
* relaxes smooth muscle to prevent ctxn
* induces labor
71
human placental lactogen (hPL)
* growth hormone that stimulates mom's metabolism to supply baby w/ glucose
* stimulates breast development
72
human chorionic gonadotropin (hCG) fxn
* produced by placenta following implantation
* detected 8-10 days post-conception
* preggo test positive
73
monozygotic twins
* identical
* 1 egg, 1 sperm
* same sex/genotype
74
dichorionic diamniotic
*division shortly after fertilization
•2 amnions
•2 chorions
•2 placentas
75
monochorionic diamniotic
*division 4-8 days after fertilization
•2 amnions
•1 chorion
•1 placenta
76
monochorionid monoamniotic
```
*division 8+ days after fertilization
•1 amnion
•1 chorion
•1 placenta
*conjoined twins
```
77
dizygotic twins
* fraternal
* 2 eggs, 2 sperm
* may be different sexes
* 2 amnions, 2 chorions, 2 placentas
* different genotype
