15.1- fertilization and embryonic development

Question 1

developmental changes are divided into what 2 stages

Answer 1

embryonic and fetal

Question 2

embryonic period consists of ___

Answer 2

rapid cell division, organs form, supporting structures form

Question 3

fetal period consists of

Answer 3

rapid growth, organs function, systems form

Question 4

fertilization is AKA

Answer 4

conception

Question 5

fertilization=

Answer 5

fusion of sperm and egg to form a single cell with 46 chromosomes (23 pairs)

Question 6

how many chromosomes does a human have

Answer 6

46`

Question 7

how many pairs of chromosomes does a human have

Answer 7

23

Question 8

how does the egg travel down the oviduct (2)

Answer 8

peristalsis and cillia

Question 9

after the egg is released during ovulation, how many days does it take to reach the uterus

Answer 9

4 days

Question 10

how many hours does the egg have to get fertilized and where does it take place

Answer 10

24 hours
oviduct

Question 11

what kills and/or loses many sperm (2)

Answer 11

the females acidic and some sperm travel into the wrong oviduct

Question 12

what allows the sperm to enter the egg

Answer 12

enzymes located in the acrosome (head)

Question 13

the egg is surrounded by which 2 layers

Answer 13

1- zona pellucida
2- corona radiata

Question 14

what is the zona pellucida

Answer 14

clear layer of protein and carbs surrounding egg plasma membrane

Question 15

what is the corona radiata

Answer 15

follicle cells surrounding the zona pellucida that nourish the egg in the ovary

Question 16

sperm must break through which 2 layers to enter the egg

Answer 16

• zona pellucida
• corona radiata

Question 17

what happens when one sperm enters the egg

Answer 17

one sperm enters- plasma membrane depolarizes- no more sperm can enter

Question 18

what is a zygote

Answer 18

first diploid 2n pair

Question 19

hows a zygote created

Answer 19

23 chromosomes from each gamete combine to form 23 chromosomes pairs

Question 20

what happens during cleavage

Answer 20

the single celled zygote begins to divide but stays the same size (1 cell-2cells-4cells…)

Question 21

what’s a structure composed of 16 undifferentiated cells called

Answer 21

morula

Question 22

morula reaches the uterus ___ days after fertilization

Answer 22

4

Question 23

morula fills with ____ to form a ___ ___ called the ___/____

Answer 23

fluid
hollow hole
blastocyst/blastula

Question 24

2 layers of the blastocyst + functions

Answer 24

inner cell mass (developed into embryo)
trophoblast (outer layer…cont)

Question 25

trophoblast turns into ___ which then turns into ___

Answer 25

turns into the chorion which helps form the placenta

Question 26

implantation occurs on days ___

Answer 26

5-7

Question 27

trophoblast secretes ___ which____

Answer 27

enzymes which digest a small hole in the endometrium

Question 28

what happens once the trophoblast secretes enzymes (3)

Answer 28

- blastula sinks into the hole in endometrium with inner cell mass against the wall - endometrium tries to heal wound therefore trapping the blastocyst - implantation has occurred and the woman is now pregnant

Question 29

what needs to be prevented in order for the blastocyst and endometrium to not be lost

Answer 29

menstruation

Question 30

what do trophoblasts secrete to maintain corpus luteum

Answer 30

hCG (human chorionic gonadotropin)

Question 31

hCG mimics LH meaning that ___

Answer 31

estrogen and progesterone levels remain high

Question 32

what prevents menstruation

Answer 32

high estrogen and progesterone levels

Question 33

during the second week the blastocyst becomes a ___

Answer 33

gastrula

Question 34

___ forms between inner cell mass and trophoblast

Answer 34

amniotic cavity

Question 35

the inner cell mass develops into what 3 primary germ layers

Answer 35

1- ectoderm 2- mesoderm- 3- endoderm

Question 36

ectoderm=

Answer 36

skin and nerves

Question 37

mesoderm=

Answer 37

middle layer muscles, skeleton, reproductive, excretory and circulatory systems

Question 38

endoderm=

Answer 38

digestive and respiratory systems

Question 39

morphogenisis=

Answer 39

developing distinct structures that make up an organism via differentiation

Question 40

organs are formed between weeks

Answer 40

3-8

Question 41

what forms the mesoderm cells that will eventually become the skeleton

Answer 41

notochord

Question 42

during the 3rd week what develops from the ectoderm and what will it become

Answer 42

neural tube developed and will become brain and spinal cord

Question 43

4th week =(4)

Answer 43

rapid development circulatory system, lungs and kidneys, head+facial features

Question 44

5th week= (3)

Answer 44

head grows, eyes open, brain quickly develops

Question 45

6th week=(3)

Answer 45

brain continues to develop arms and legs grow gonads produce hormones to developed external genitals

Question 46

7th and 8th weeks= (4)

Answer 46

organs form nervous systems become active skeleton has developed cant tell sex yet (genitals aren't fully developed)

Question 47

after 8 weeks its now considered a ____

Answer 47

fetus

Question 48

yolk sac is attached to ___

Answer 48

attached to abdomen of embryo

Question 49

yolk sac fuction (2)

Answer 49

produces first blood cells and future egg and sperm involved in forming digestive system

Question 50

Amnion function (2)

Answer 50

lines amniotic cavity and produces fluid to cushion embryo, maintain temp. and provide space for developement breaks before birth "water breaking"

Question 51

allantoil function

Answer 51

forms umbilical cord

Question 52

chorion function

Answer 52

forms fetal part of placenta

Question 53

placenta is part of the __ and attaches ___ to ____

Answer 53

chorion and attaches embryo/fetus to uterine wall

Question 54

placenta function (2)

Answer 54

attaches embryo/fetus to uterine wall to allow metabolic exchange with mother (hormones nutrients antibodies etc can travel) secretes estrogen, progesterone and hCG

Question 55

Umbilical cord contains __ arteries and __ veins

Answer 55

2 arteries 1 vein

Question 56

arteries of umbilical cord carry

Answer 56

deoxygenated blood away from fetus

Question 57

vein of umbilical cord carrys

Answer 57

oxygenated blood towards fetus