Ch. 3 fetal development Flashcards
(113 cards)
1
Q
how many chromosomes are in each body cell. how are they broken down
A
46
22 pairs of autosomes and 1 pair of sex chromosomes
2
Q
Teratogens
A
things in medicine that cause damage to growing cells
3
Q
Mitosis
A
cell division for replacing dead cells and growing. makes cells with 46 chromosomes
4
Q
the diploid number of chromosomes
A
46 in a body cell
5
Q
spermatogenesis
A
process of mitosis in the sperm
6
Q
oogenesis
A
mitosis in the ovum
7
Q
Meiosis
A
cell division where reproductive cells under go 2 divisions reducing the number of chromosomes to 23
8
Q
the haploid number of chromosomes
A
23, sex cells
9
Q
when does meiosis happen in the sperm
A
before it reaches the fallopian tube
10
Q
when does meiosis happen in the ovum
A
when it is fertalized
11
Q
Gametogenesis
A
the formation of gametes by meiosis
12
Q
How many sperm are made by one spermatocyte
A
4
13
Q
Where does fertilization occur
A
the outer third of the Fallopian tube near the ovary
14
Q
How long does an ovum survive
A
24 hrs after ovulation
15
Q
What in the female effects gender
A
pH and estrogen
16
Q
When does the male embryo differentiate
A
6-7 weeks
17
Q
When does testosterone secretion begin in reproduction
A
8 weeks
18
Q
what is needed for female gonads to form
A
presence of estrogen and absence of testosterone
19
Q
When do female gonads develop ovaries
A
6-8 weeks
20
Q
Recessive disorder
A
alteration of defect in one gene
21
Q
Dominant disorder
A
defect in both genes
22
Q
if only one gene is normal what are the chances of developing a disorder
A
50%
23
Q
How is a zygote formed
A
when a sperm and egg combine
24
Q
what happens when a zygote is transported through the fallopian tube
A
rapid mitosis or cleavage but, the size doesn’t change just the number of cells
25
cleavage
begins with 2 cells that divide into 4 then 8 to make blastomere
26
Morula
the solid ball formed by cleavage
27
morula
enters uterus on third day and hangs out for 2-4 days before forming a cavity with 2 layers
28
Blastocyst
the inner layer of a morula, solid mass, turns into embryo and embryonic membrane
29
Trophoblast
outer layer that becomes the embryonic membrane, the chorion
30
Where does the zygote usually implant
in the upper part of the posterior uterine wall
31
Decidua
the endometrium after the zygote implants
32
Decidua basalis
area under the blastocyst that becomes the maternal placenta
33
What happens after implantation
the cells differentiate and develop special functions
34
What appears after implantation
chorion
amnion
yolk sac
primary germ layers
35
chorion
- what does it develop from
- what does it do
- what is it
- the trophoblast
- envelops the amnion, embryo and yolk sac and form the embryonic or fetal portion of the placenta
- thick membrane with villi
36
amnion
- what is it
- what does it do
- what does it from
- second membrane that meets the inside of the chorion
- covers and protects the embryo
- boundaries of the amniotic cavity
37
amniotic sac
the chorion and amnion together
38
describe amniotic fluid
clear
mild odor
contains bits of vernix and lanugo
39
vernix
fetal skin covering
40
lanugo
fetal hair on the skin
41
how much amniotic fluid
- 10 weeks
- 20 weeks
- 37 week
- 30 mL
- 350 mL
- 1000 mL
42
How much amniotic fluid per day does a fetus swallow
400 mL
43
Functions of amniotic fluid
- maintain termperture
- prevents sac from sticking to skin
- allows symmetrical growth
- allows fetal movement
- acts as protection
44
When does the yolk sac form and where
9th day
| in the blastocyst
45
when does the yolk sac function and what does it do
about 6 weeks until liver takes over
| initiates RBC production
46
What happens when the yolk sac finishes its job
umbilical cord covers it and it degenerates
47
what happens after implantation
the zygote in the blastocyst stage turns its embryonic disk into primary germ layers
48
What are the primary germ layers
ectoderm
mesoderm
endoderm
49
what does the ectoderm become
- outer skin
- oil glands
- hair follicles
- nails and hair
- external sense organs
- mucous membranes of mouth and anus
50
What does the mesoderm become
- true skin
- skeleton
- bone and cartilage
- connective tissue
- muscles
- blood and vessels
- kidneys
- gonads
51
what does the endoderm become
- lining of throat
- lining of GI tract
- lining of bladder and urethra
52
time period for embryo
2-8 weeks
53
time period for fetus
9 weeks - birth
54
What happens the second week
ectoderm, endoderm and amnion begin to develop
55
what develops week 3
single tubular heart
neural tube
primitive spine and brain
56
what develops in week 4
```
esophagus and trachea
stomach
neural tube closes
forebrain
limb buds
ears and eyes begin
```
57
what develops in week 6
```
auditory canal
eyes obvious
heart has chambers
nasal cavity
upper lip
```
58
what develops in week 8
```
human appearance
purposeful movement
tail disappears
sex organs
start of most structures
```
59
what develops in week 17
```
genitalia visable
leg movement visable
feel movement
bones ossified
eye movement
sucks and swallows fluid
ova
no true skin of fat
```
60
week 25
```
skin wrinkled
lean body
eyes open
VIABLE
quickening
has sleep schedule
vernix careosa
Lanugo
brown fat forms
surfactant
fingernails
resp. movement
```
61
week 29
assumes cephalic position
CNS functioning
spleen stops making blood
bone marrow makes blood
62
weed 36
head and abd equal
| subcut fat
63
what is full term
39-40 weeks
64
what are the measurements full term
- length
- weight
- 48 to 52 cm (18-21 in)
| - 3000 to 3600 g (6 lb to 7 lb 15 oz)
65
week 3
mesoderm and neural tube forms
| primitive heart starts to pump
66
when does the placenta attach
12 weeks (end of first trimester)
67
abnormal attachment to uterine wall results in
placenta accreta or placenta previa
68
what is the age of viability
20 weeks
69
placenta
temporary organ for resp., nutrition and excretion, endocrine gland
70
when does the placenta form
when the chorionic villi of the embryo extends into the mother's decidua basalis
71
where does the maternal part of the placenta come from
decidua basalis
72
what does the fetal side of the placenta come from
chorionic villi and chorionic blood vessels
73
what does the amnion do
covers the fetal side and umbilical cord giving them a gray shiny look
74
what does enlarged placenta signal
maternal diabetes
| increased morbidity of fetus
75
what causes small placenta
stress
undernutrition
steriods
chronic hypoxia
76
how much does the placenta weigh at term
1/6 weight of baby
77
how does deoxygenated blood and waste leave the fetus
2 umbilical arteries that enter placenta through branch of main stem villus which comes from the intervillous space (lacuna)
78
how does oxygenated blood from mom get to baby
goes into the intervillous space from spiral arteries in the decidua
79
what hormones are made by the placenta
- progesterone
- estrogen
- human chorionic gonadotropin (hCG)
- human placental lactogen (hPL)
80
function of progesterone in pregnancy
- maintain implantation
- reduces contractions and prevents miscarraige
- prepares milk
- stimulates testosterone in male baby
81
function of estrogen in pregnancy
- stimulates uterine growth
- increases blood flow to uterus
- helps development of breast ducts for milk
82
effects of estrogen not directly related to pregnancy
- mask of pregnancy
- vascular changes to skin and membranes in nose and mouth
- increased saliva
83
function of Human chorionic gonadotropin
-makes corpus luteum to keep making estrogen and progesterone to sustain pregnancy
84
what do pregnancy test check for and how soon
hCG, 7-9 days after fertilization
85
Function of Human placental lactogen
-decrease insulin sensitivity and glucose utilization in mom so baby has what it needs to grow
86
what is in the umbilical cord
2 arteries and a vein
87
Wharton jelly
covers the vessels in the umbilical cord
88
how long is the cord
55cm (22 in)
89
ductus venosus
fetal circulatory shunt
| sends some blood away from the liver as it goes to the placenta
90
foramen ovale
fetal circulatory shunt
| diverts most blood from the right atrium to the left instead of going to lungs
91
ductus arteriousus
fetal circulatory shunt
| diverts most blood from pulmonary artery to the aorta
92
why does the foramen ovale close after birth
pressure on the right side of the heart falls as the lungs fill
93
what causes the ductus arteriousus to constrict after birth
oxygen levels rise
94
when does the ductus venosus close after birth
when flow from the umbilical cord stops
95
when does the foramen ovale close
- functionally
- permanently
- 2 hr after birth
| - 3 months
96
when does the ductus arteriousus close
- functionally
- permanently
- 15 hrs
| - 3 weeks
97
when does the ductus venosus close
- functionally
- permanently
- when the cord is cut
| - 1 week
98
what do the ductus arteriousus and ductus venosus become after they close permanently
ligaments
99
what can cause the foramen ovale to reopen
conditions that keep lungs from filling fully
100
what can cause the ductus arteriosus to remain open
conditions that lower blood oxygen levels
101
what causes wet lung in newborns
c-section or rapid delivery
102
when is the fetus most susceptible to external influences
first 3 months
103
what does pancreatic beta cells cause
impaired insulin secretion
104
what can happen in utero and increase risk for hypertension later in life
changes in vascular or renal structures or hormonal systems from malnourishment
105
what can impaired fetal liver growth late in gestation cause
impaired lipid metabolism and increased cholesterol level
106
what is used for assessment of fetal growth
- weight
- length
- placenta size
- head and abd size
107
monozygotic twins
identicle
108
physical differences in monozygotic twins are caused by
differences in blood supply from the placenta
109
monozygotic twins begin to develop when
end of first week after fertilization
110
what things to monozygotic twins share
- chorion
- placenta
- some vessels
111
what causes conjoined twins
embryonic disk not dividing completely
112
dizygotic twins
fraternal twins
113
what increases chances of dizygotic twins
genetics and older age
