15.1- fertilization and embryonic development Flashcards

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1
Q

developmental changes are divided into what 2 stages

A

embryonic and fetal

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2
Q

embryonic period consists of ___

A

rapid cell division, organs form, supporting structures form

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3
Q

fetal period consists of

A

rapid growth, organs function, systems form

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4
Q

fertilization is AKA

A

conception

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5
Q

fertilization=

A

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

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6
Q

how many chromosomes does a human have

A

46`

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7
Q

how many pairs of chromosomes does a human have

A

23

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8
Q

how does the egg travel down the oviduct (2)

A

peristalsis and cillia

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9
Q

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

A

4 days

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10
Q

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

A

24 hours
oviduct

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11
Q

what kills and/or loses many sperm (2)

A

the females acidic and some sperm travel into the wrong oviduct

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12
Q

what allows the sperm to enter the egg

A

enzymes located in the acrosome (head)

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13
Q

the egg is surrounded by which 2 layers

A

1- zona pellucida
2- corona radiata

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14
Q

what is the zona pellucida

A

clear layer of protein and carbs surrounding egg plasma membrane

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15
Q

what is the corona radiata

A

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

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16
Q

sperm must break through which 2 layers to enter the egg

A
  • zona pellucida
  • corona radiata
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17
Q

what happens when one sperm enters the egg

A

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

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18
Q

what is a zygote

A

first diploid 2n pair

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19
Q

hows a zygote created

A

23 chromosomes from each gamete combine to form 23 chromosomes pairs

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20
Q

what happens during cleavage

A

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

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21
Q

what’s a structure composed of 16 undifferentiated cells called

A

morula

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22
Q

morula reaches the uterus ___ days after fertilization

A

4

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23
Q

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

A

fluid
hollow hole
blastocyst/blastula

24
Q

2 layers of the blastocyst + functions

A

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

25
Q

trophoblast turns into ___ which then turns into ___

A

turns into the chorion which helps form the placenta

26
Q

implantation occurs on days ___

A

5-7

27
Q

trophoblast secretes ___ which____

A

enzymes which digest a small hole in the endometrium

28
Q

what happens once the trophoblast secretes enzymes (3)

A
  • 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
29
Q

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

A

menstruation

30
Q

what do trophoblasts secrete to maintain corpus luteum

A

hCG (human chorionic gonadotropin)

31
Q

hCG mimics LH meaning that ___

A

estrogen and progesterone levels remain high

32
Q

what prevents menstruation

A

high estrogen and progesterone levels

33
Q

during the second week the blastocyst becomes a ___

A

gastrula

34
Q

___ forms between inner cell mass and trophoblast

A

amniotic cavity

35
Q

the inner cell mass develops into what 3 primary germ layers

A

1- ectoderm
2- mesoderm-
3- endoderm

36
Q

ectoderm=

A

skin and nerves

37
Q

mesoderm=

A

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

38
Q

endoderm=

A

digestive and respiratory systems

39
Q

morphogenisis=

A

developing distinct structures that make up an organism via differentiation

40
Q

organs are formed between weeks

A

3-8

41
Q

what forms the mesoderm cells that will eventually become the skeleton

A

notochord

42
Q

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

A

neural tube developed and will become brain and spinal cord

43
Q

4th week =(4)

A

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

44
Q

5th week= (3)

A

head grows, eyes open, brain quickly develops

45
Q

6th week=(3)

A

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

46
Q

7th and 8th weeks= (4)

A

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

47
Q

after 8 weeks its now considered a ____

A

fetus

48
Q

yolk sac is attached to ___

A

attached to abdomen of embryo

49
Q

yolk sac fuction (2)

A

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

50
Q

Amnion function (2)

A

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

51
Q

allantoil function

A

forms umbilical cord

52
Q

chorion function

A

forms fetal part of placenta

53
Q

placenta is part of the __ and attaches ___ to ____

A

chorion and attaches embryo/fetus to uterine wall

54
Q

placenta function (2)

A

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

55
Q

Umbilical cord contains __ arteries and __ veins

A

2 arteries 1 vein

56
Q

arteries of umbilical cord carry

A

deoxygenated blood away from fetus

57
Q

vein of umbilical cord carrys

A

oxygenated blood towards fetus