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Biology reproduction > Fertilization and fetal development > Flashcards

Fertilization and fetal development Flashcards

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1
Q

what is external fertilization?

A

fertilization occurring outside the body– usually in water

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2
Q

what is internal fertilization?

A

sperm cells transferred into the body during copulation( sex)

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3
Q

animal examples of internal and external fertilization

A

1) aquatic animals(fish) 2) reptiles and birds and humans

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4
Q

advantages of internal fertilization

A

1) increases the chance that the gametes will meet = species have to produce fewer gametes

2) fertilized ovum can be enclosed in a protective covering = shell/ remain in the body during development.

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5
Q

when does human fertilization occur?

A

when one sperm cells fuse with the secondary oocyte

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6
Q

what does the fusion of a sperm and secondary oocyte create?

A

a zygote

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7
Q

where does the formation of a zygote take place in?

A

the oviduct

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8
Q

what is the purpose of the human fertilization system?

A

to prevent polyspermy– entry of more than one sperm cell nucleus

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9
Q

what is the first step in fertilization?

A

large amounts of sperm ejaculated into vagina during sexual intercourse

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10
Q

how many sperm survive getting to through the vagina?

A

only a few make it to through the cervix and uterus

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11
Q

second step to fertilization-name?

A

aerosome reaction

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12
Q

what happens during aerosome reaction?

A

sperm binds to the zona pellucida the contents of the aerosome are released

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13
Q

what helps the sperm get through the zona pellucida?

A

the head of the sperm contains sacs of enzymes that help it digest through the zona pellucida to get to the egg.

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14
Q

what enzyme is contained in the sperm head?

A

aerosome enzyme

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15
Q

what happens in the third step of fertilization?

A

penetration of the egg membrane

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16
Q

how is step 3 of fertilization done?

A

aerosome reaction exposes an area of the membrane to the sperm where its protein can bind to the egg membranes receptors.

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17
Q

result of step 3 of fertilization?

A

the binding of sperms protein to egg membranes proteins, allows its membrane to fuse with the eggs membrane

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18
Q

step 4 of fertilization

A

cortical reaction– entry of sperm nucleus activates egg(complete meiosis 2) cortical granules released from egg that causes binding proteins on egg membrane to degenerate so no more sperm can bind.

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19
Q

what causes the hardening if the zona pellucida?

A

the breaking down of the proteins on the egg membrane

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20
Q

what does the hardening of the zona pedullcida achieve?

A

further protect the egg as well as keeping other sperm out

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21
Q

what are cortical granules?

A

secretory vesicles located in the cortex of unfertilized oocytes

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22
Q

what do cortical granules cause?

A

the binding of proteins from sperm to egg

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23
Q

end result of fertilization step 4?

A

an embryo development

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24
Q

what stage comes right after successful fertilization?

A

blastocyst stage

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25
what happens in the blastocyst stage?
after division of mitosis, the cells made are similar-- after 2 weeks they specialize
26
what happens after fertilization?
the zygote travels down the oviduct towards the uterus, while it divides through mitosis a series of times
27
what happens when zygote reaches the uterus?
it has divided into an almost hollow ball of cells (blastocyst)
28
whats a blastocyst?
hollow ball of cells created by continues division of mitosis after fertilization of eggs
29
what do the outer walls of the blastocyst become?
placenta
30
what do the inner walls of the blastocyst become?
embryo
31
what is implantation?
6-10 days after fertilization-- the blastocyst attach itself to the endometrium lining
32
what happens after blastocyst implants itself in uterine wall?
sends a signal (hormone)=HCG
33
what does HCG mean?
travels blood steam and affects the ovary, as well as signals to ovary to maintain the corpus luteum.
34
what does the corpus luteum do in first trimester?
produces progesterone and estrogen
35
at what stage is the zygote called an embryo?
first trimester
36
what's the process of specialization of cells called?
gasturiation
37
what does gastrulation produce?
a gasturla
38
what does a gastrula contain?
3 germ layers
39
what does gasturiation do?
causes cells to get specialized by placing cells in the 3 germ layers
40
what does the cells in the ectoderm form?
skin, nervous system,
41
what does the cells in the mesoderm form?
kidney, skeleton, muscles, blood vessels and gonads
42
what does the cells in the endoderm form?
lungs and lining of the digestive tract
43
when does the embryo form important parts?
10-14th day
44
what part of the embryo form important structures?
outer portions of embryo
45
what does the yolk sac do?
supplies nutrients for the first 2 months of development
46
what is the amnion ?
fluid filled sac that protects the body of embryo
47
what is does the allantois do?
removes waste
48
what does the chorion do?
surrounds everything
49
what are 4 important structures of the embryo?
yolk sac, amnion, allantois, chorion
50
when does the placenta fully form?
3 months in
51
what does is the placenta responsible for?
secreting estrogen and progesterone to maintain pregnancy and developing nutrients and removing waste for the developing fetus
52
what is the placenta made up of ?
endometrium material and small projections from the chorin surrounding the embryo called chorionic villi
53
what is the chronic villi?
grow out of the chorin into the endometrium and are rich in capillaries
54
what do the chronic villi do?
provide a large surface area for the exchange if nutrients and waste between the mothers blood and that of the fetus
55
the relationship between fetus blood and mothers blood?
never mix,-- fetal blood remain in the chronic villi surrounded by maternal (mothers) blood flowing into the endometrial spaces.
56
what are endometrial spaces?
the inner most lining of the uterus
57
the purpose of having the maternal blood flowing into the endometrial spaces?
allows the mothers blood to come in as close contact as possible without the 2 mixing.
58
what attaches the embryo to the placenta?
the umbilical cord
59
what is the job of the umbilical cord?
to carry fetal blood to the placenta
60
how does the umbilical cord carry blood to the fetus?
umbilical arteries to the placenta and umbilical veins (singular) to the fetus
61
how does the mother provide oxygen and nutrients to child?
through her blood-- umbilical arteries divide into capillaries in the chronic villi, where the blood can diffuse from mom to baby.
62
what happens to the cellular respiration byproduct?
co2 gets diffuses from the fetus back to the mother
63
what is gestation?
period of time between conception and birth
64
how long is human gestation?
40 weeks
65
what id gestation divided into?
trimesters-- 3
66
how long do each trimester last?
3 months~
67
what happens in trimesters?
major development changes occurring in every trimester
68
what happens in trimester 2 week 24?
fetus-- 300 mm long becomes more active and all organs are formed but done function
69
at happens in trimester 1 week 9?
first bone cells are formed, embryo id called fetus
70
what happens during the 3rd trimester?
rapid increase in size and vital brain tissue is build and nervous system is develop.
71
what happens in 2nd trimester week 16
skeleton begins to form, brain grows rapidly and the nervous system begins to form + mother can feel movement.
72
what happens in 1st trimester week 12
all major organs begin to form (liver ,brain, stomach, heart) the fetus is 100 mm long noticeable head and limbs sex can be identifies by ultra sounds
73
what happens in trimester 1 week 6
eyes begin to form as well as spin formation
74
what trimester plus week does the nervous system begin developing and when it finish's?
2nd trimester-- week 16 3rd trimester--week 26-27
75
why is it important for mother to eat healthy when pregnant?
because the fetus receives all of its nutrients and oxygen from mother blood. -- anything she eats drinks inhales from environment gets in her blood
76
what's the most crucial period of development for the baby?
1ist trimester-- because the limbs eyes and major organs are formed in this stage, complications here can result in unhealthy baby/unfinished
77
what effect does ciggrete smoke have on baby?
constricts blood vessels= prevents it from getting enough oxygen
78
alcohol affects on baby?
the function of the fetus's brain and central nervous system as well as physical development (FAS)
79
FAS is caused by what substance abuse during pregnancy?
alcohol
80
why is the age of the mother a problem in pregnancy?
too old(45)-- body is weak unable to carry baby + body gets tired of meiosis so its not done as well=chromosomes mutation(1/20) too young+ lots of strain on the body, needs energy to grow mom and baby + higher risk of premature birth
81
other risk factors of pregnancy?
radiation, pollutants-PBC's and mercury
82
what can cause genetic mutation?
radiation, pollutants-PBC's and mercury and if woman over 45 gets pregnant.

Biology reproduction (5 decks)

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