reproduction; fertilization and fetal development

Question 1

internal fertilization advantages

Answer 1

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

Question 2

human fertilization 1- fertilization moment?

Answer 2

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

Question 3

human fertilization 2- what is it designed to prevent?

Answer 3

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

Question 4

sperm only has __________ to reach _______________ _____

Answer 4

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

Question 5

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

Answer 5

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

Question 6

steps of fertilization 2- acrosome reaction:

Answer 6

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

Question 7

steps of fertilization 2.2- zona pellucida

Answer 7

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

Question 8

steps of fertilization 2.3- acrosome

Answer 8

a sac of enzymes contained in the head of sperm

Question 9

steps of fertilization 3- penetration of the egg membrane

Answer 9

> > 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

Question 10

steps of fertilization 4- cortical reaction

Answer 10

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

Question 11

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

Answer 11

after fertilization, zygote travels down oviduct towards the uterus

Question 12

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

Answer 12

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

Question 13

blastocyst pt 3- how will blastocyst form?

Answer 13

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

Question 14

blastocyst begins what? what does it do?

Answer 14

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

Question 15

implantation 1- what happens after ___________ is implanted?

Answer 15

when blastocyst is implanted, it secretes: HCG

Question 16

implantation 2- HCG what does it do?

Answer 16

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

Question 17

implantation 3- what does the corpus luteum do?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

embryo dvlpmt 1.2- gastrulation + gastrula

Answer 19

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

Question 20

embryo dvlpmt 2- how are germ layers positioned?

Answer 20

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

Question 21

embryo dvlpmt 2.2.1- ectoderm

Answer 21

forms skin + nervous system

Question 22

embryo dvlpmt 2.2.2- mesoderm

Answer 22

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

Question 23

embryo dvlpmt 2.2.3- endoderm

Answer 23

forms the lungs and the lining of digestive tract

Question 24

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

Answer 24

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

Question 25

embryo dvlpmt 3.2.1- yolk sac

Answer 25

supplies nutrients for the first two months of development

Question 26

embryo dvlpmt 3.2.2- amnion

Answer 26

fluid filled sac that protects the embryo + does cellular respiration

Question 27

embryo dvlpmt 3.2.3- allantois

Answer 27

removes waste

Question 28

embryo dvlpmt 3.2.4- chorion

Answer 28

surrounds everything

Question 29

embryo dvlpmt 3.3- amniotic sac and fluid?

Answer 29

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.

Question 30

what are gonads?

Answer 30

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

Question 31

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

Answer 31

no genes are not always on depending on the cell >> 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.

Question 32

what is the purpose of the placenta?

Answer 32

responsible for delivering nutrients and waste for developing fetus

Question 33

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

Answer 33

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

Question 34

after the first three months what happens to placenta?

Answer 34

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

Question 35

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

Answer 35

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.

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

ubc b- what do umbilical arteries do?

Answer 38

umbilical arteries divide into capillaries within chorionic villi

Question 39

ubc c- how do nutrients and o2 cycle

Answer 39

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

Question 40

gestation 1- what is gestation?

Answer 40

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

Question 41

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

Answer 41

each trimester lasts 3 months with major developmental changes occurring in every trimester first trimester second trimester third trimester } 3 trimesters in total

Question 42

gestation 2.2.1a- first trimester dvlpmt

Answer 42

@6 weeks >> 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

Question 43

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

Answer 43

@ 12 weeks >>fetus is 100mm long, has noticeable head and limbs sex can be determined via ultrasound embryo is most vulnerable to outside influences

Question 44

gestation 2.2.2a- second trimester dvlpmt

Answer 44

@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.

Question 45

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

Answer 45

fetus can use its muscles to move spontaneously

Question 46

gestation 2.2.3a - third trimester dvlpmt

Answer 46

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

Question 47

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

Answer 47

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

Question 48

risks factors during dvlpmt -- first trimester fetus

Answer 48

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

Question 49

risk factors during dvlpmt-- age

Answer 49

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

Question 50

risk factors during dvlpmt- other factors

Answer 50

-radiation -pollutants -mercury