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b i o l o g y > reproduction; fertilization and fetal development > Flashcards

reproduction; fertilization and fetal development Flashcards

1
Q

internal fertilization advantages

A
  1. increases chance that gametes will meet = species have to produce fewer gametes
    1. fertilized ovum can be enclosed in a protective covering&raquo_space; remains in female’s body during dvlpmt
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2
Q

human fertilization 1- fertilization moment?

A

fertilization = moment sperm cells f u s e s w/ secondary oocyte to form zygote
occurs in the oviducts of female

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3
Q

human fertilization 2- what is it designed to prevent?

A

its process is meant to prevent polyspermy» entry of more than one sperm cell nuclei

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4
Q

sperm only has __________ to reach _______________ _____

A

3-5 days, ovulated eggs (there’s two paths of two eggs, only one of them is ovulated at a time)

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5
Q

steps of fertilization 1- large number of what enters vagina? how much of it made it through?

A

large number of sperm are ejaculated into vagina during copulation
only a small number make it through cervix and uterus

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6
Q

steps of fertilization 2- acrosome reaction:

A

sperm binds to zona pellucida, contents of acrosome are released , enzymes digest zona pellucida

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7
Q

steps of fertilization 2.2- zona pellucida

A

secondary oocyte = surrounded by zona pellucida
zona pellucida = glycoprotein coat that prevents polyspermy

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8
Q

steps of fertilization 2.3- acrosome

A

a sac of enzymes contained in the head of sperm

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9
Q

steps of fertilization 3- penetration of the egg membrane

A

> > acrosome reaction exposes an area of membrane on the sperm w/ proteins that can bind to egg membrane
&raquo_space; the first sperm that gets through binds it’s membrane with egg’s
membrane/ sperm nuclei enters egg cell

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10
Q

steps of fertilization 4- cortical reaction

A

sperm entry = activates egg
contents of c o r t i c a l g r a n u l e s = released from egg
> results in binding proteins on egg membrane = digested so sperm
can’t bind
also results in the hardening of the zona pellucida

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11
Q

blastocyst pt 1- what is travelling after fertilization + where to where?

A

after fertilization, zygote travels down oviduct towards the uterus

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12
Q

blastocyst pt 2- what does zygote do + when does it reach uterus, how does it end up?

A

as zygote travels, it begins the process: mitosis with series of divisions
zygote reaches uterus 24-36 hours later: now it’s almost a hallow ball of
cells called blastocyst

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13
Q

blastocyst pt 3- how will blastocyst form?

A

outer cells of blastocyst will become the placenta, while inner mass becomes embryo

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14
Q

blastocyst begins what? what does it do?

A

blastocyst -> i m p l a n t a t i o n : 6-10 days after fertilization, blastocyst attaches itself to the endometrium lining

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15
Q

implantation 1- what happens after ___________ is implanted?

A

when blastocyst is implanted, it secretes: HCG

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16
Q

implantation 2- HCG what does it do?

A

travels in blood stream + affects ovary which maintains the corpus luteum

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17
Q

implantation 3- what does the corpus luteum do?

A

produces progesterone + estrogen though the first trimester, @ this stage it’s called zygote&raquo_space; e m b r y o

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18
Q

embryo dvlpmt 1- what happens in the second week of pregnancy? what’s the process called?

A

in the second week of being preg» cells begin starts to specialize, this process is called gastrulation which produces a gastrula

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19
Q

embryo dvlpmt 1.2- gastrulation + gastrula

A

during this cells in embryo become arranged in 3 layers = germ layers
} gastrula is the embryo at this stage composed of these 3 germ layers

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20
Q

embryo dvlpmt 2- how are germ layers positioned?

A

cells move to specific position to produce layers:
ectoderm
mesoderm
endoderm

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21
Q

embryo dvlpmt 2.2.1- ectoderm

A

forms skin + nervous system

22
Q

embryo dvlpmt 2.2.2- mesoderm

A

forms kindeys, skeleton, muscles, blood vessels, and gonads

23
Q

embryo dvlpmt 2.2.3- endoderm

A

forms the lungs and the lining of digestive tract

24
Q

embryo dvlpmt 3- what is formed during the 10th to fourteenth day of pregnancy

A

between 10-14 days of pregnancy, outer portions of embryo form 4 parts
yolk sac
amnion
allantois
chorion

25
Q

embryo dvlpmt 3.2.1- yolk sac

A

supplies nutrients for the first two months of development

26
Q

embryo dvlpmt 3.2.2- amnion

A

fluid filled sac that protects the embryo
+ does cellular respiration

27
Q

embryo dvlpmt 3.2.3- allantois

A

removes waste

28
Q

embryo dvlpmt 3.2.4- chorion

A

surrounds everything

29
Q

embryo dvlpmt 3.3- amniotic sac and fluid?

A

amniotic sac = sac where the baby is developed created by the membranes: amnion and chorion

amniotic fluid = the fluid within the sac that surrounds the baby and provides its nutrients.

30
Q

what are gonads?

A

ovaries and the testicles } the reproductive systems of females and males

31
Q

depending on the location of cells, are the genes on or off? why?

A

no genes are not always on depending on the cell&raquo_space; different genes are needed for different areas of the body. it will turn on or off depending on the location/body part that c h e m i c a l s i g n a l s tell them to create.

32
Q

what is the purpose of the placenta?

A

responsible for delivering nutrients and waste for developing fetus

33
Q

what in our parts in our body make up the placenta?

A

placenta’s made up of maternal endometrium + small projections from chorion surrounding embryo: chorionic villi

34
Q

after the first three months what happens to placenta?

A

placenta fully dvlps and begin producing p l a c e n t a l estrogen and progesterone to m a i n t a i n p r e g n a n c y

35
Q

cv a- what is the chorionic villi’s (cv) main purpose?

A

to provide a l a r g e s u r f a c e a r e a for exchange of nutrients and waste between mother’s and fetus’ blood.

36
Q

cv b- where does the fetal blood remain? what does this allow?

A

fetal blood remains in the capillaries of the chorionic villi = surrounded by maternal blood flowing into endometrial spaces
allows mom’s blood to be as close as possible to the baby’s without
having any actual contact

37
Q

ubc a- umbilical cord, what is it attached to? how does this attachment function for fetus (like the pulmonary stuff)?

A

umbilical cord is how the embryo is attached to placenta
; fetal blood is carried to placenta by t w o umbilical arteries and carried back to the fetus by a s i n g l e umbilical vein

38
Q

ubc b- what do umbilical arteries do?

A

umbilical arteries divide into capillaries within chorionic villi

39
Q

ubc c- how do nutrients and o2 cycle

A

nutrients and oxygen d i f f u s e from mother’s blood into fetus
while waste and carbon dioxide diffuse from fetus to mother’s blood

40
Q

gestation 1- what is gestation?

A

human gestation period = 40 weeks, divided into 3 block of time called trimesters

41
Q

gestation 2 - what are trimesters? how much do we have?

A

each trimester lasts 3 months with major developmental changes occurring in every trimester

first trimester
second trimester
third trimester
} 3 trimesters in total

42
Q

gestation 2.2.1a- first trimester dvlpmt

A

@6 weeks&raquo_space; limbs, eyes, spine begin to form
@9 weeks» first bone cells form embryo + called a f e t u s
@ 12 weeks» all major organs have begun to develop: liver, brain, stomach, and heart

43
Q

gestation 2.2.1b- first trimester, what’s the size of baby? what can we identify from the baby? what events effect baby?

A

@ 12 weeks&raquo_space;fetus is 100mm long, has noticeable head and limbs

sex can be determined via ultrasound
embryo is most vulnerable to outside influences

44
Q

gestation 2.2.2a- second trimester dvlpmt

A

@16 weeks» skeleton begins to form= brain grows rapidly + nervous system begins to form
@24 weeks» fetus = 300mm long+ fetus becomes more active + all organs are formed but not fully developed.

45
Q

gestation 2.2.2b- second trimester what events effect the baby?

A

fetus can use its muscles to move spontaneously

46
Q

gestation 2.2.3a - third trimester dvlpmt

A

@26-40 weeks» there’s a rapid increase in size: vital brain tissue is built + nervous system develops

47
Q

gestation 2.2.3b- third trimester what events effect the baby?

A

fetus can survive outside the uterus w/ medical assistance’
fetus weighs more than 3000 grams
fetus becomes oriented head-down

48
Q

risks factors during dvlpmt – first trimester fetus

A

1- anything mother eats, drinks, inhales end up in her blood + cigarette
smoke constricts fetal blood vessels preventing it from getting enough oxygen.
alcohol affects the functioning of its brain + central nervous system as well as physical dvlpmt

49
Q

risk factors during dvlpmt– age

A

mom under 20 = increased chance of delivering premature baby
mom over 45 = 1/20 chance of having baby with c h r o m o s o m a l disabilities

50
Q

risk factors during dvlpmt- other factors

A

-radiation
-pollutants
-mercury

b i o l o g y (14 decks)

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