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Human Anatomy & Physiology 2 > Development > Flashcards

Flashcards in Development Deck (33):
1

the formation of primary germ layers begins at ______.

8 weeks

2

ectoderm derives into (4)

-epidermis
-lens and cornea
-nervous system
-internal ear

3

mesoderm derives into (4)

-skeleton
-muscle
-lymphoid tissues
-kidney and ureters

4

endoderm derives into (3)

-gut
-respiratory epithelium and glands
-bladder

5

placenta

-3cm thick disc
-surface facing fetus is smooth and connected to umbilical cord

6

placenta is important because it ensures_____

the fetal and mothers blood do not mix

7

what increases as the placenta villi grow

conductivity

8

placentation

-starts around day 11
-include both the mother and embryonic tissue

9

syncytiotrophoblast... (during placentation) and the mesenchyme....

grows into chorionic villi; form blood vessels from the embryoblast

10

chorionic vill... (during placentation)

digest lacunae spaces that fill with maternal blood

11

what forms the placenta (2)

stratum deciduas with the chorionic villi

12

ectopic pregnancy (2)

-blastocyst implants outside the uterus
-most of the time in the uterine tube that ruptures after 12 weeks

13

capacitation

sperm must remove a layer of cholesterol and inhibitory factors from the acrosomal vesicle that require the females secretions

14

following capacitation the sperm are

fragile, will last only 48 hours post ejaculation

15

what is the window of opportunity for pregnancy (2)

48 hours before ovulation
12-24 hours after

16

what is the last step of sperm for fertilization

capacitation

17

the first sperms to arrive must? how is this accomplished

breakdown the corona radiata; release of hyaloronidases following the acrosomal reaction

18

the second wave of sperm....

attach to receptors on the zona pellucida and also trigger acrosomal reaction

19

the first sperm to penetrate the zona pellucida....

will fuse with the plasma membrane of the egg and release its pronuclei

20

polyspermy

more than 1 sperm entering an egg

21

what are the mechanisms to prevent polyspermy?

fast block
slow block

22

fast block (3)

-penetration depolarizes the egg and causes opening of voltage sensitive sodium channels
-occurs throughout the egg
-inactivates sperm receptors on the egg

23

slow block (3)

-depolarization of the fast block causes calcium sensitive channels to open
-calcium causes release of cortical granules that are spread between the egg and zona pellucida
-fluid begins to fill the area between the zona and egg

24

zygote

fertilized egg

25

cleavage (2)

-rapid mitosis without growth
-occurs 30 hours post fertilization

26

hatching (3)

-cell mass no longer undergoing cleavage
-time egg feeds on uterine milk
-blastocyst begins to form

27

blastocyst

a hollow sphere with an outer layer and inner layer

28

inner layer of blastocyst

embryoblast (becomes embryo)

29

outer layer of blastocyst

trophoblast (becomes chorion)

30

chorion

fetal part of the placenta

31

dizygotic twins (2)

-fraternal twins
-2 eggs ovulated and fertilized

32

monozygotic twins (2)

-splitting of the embryoblast
-maternal twins

33

syncytiotrophoblast (3)

-fusion of the trophoblast
-secretes HCG
-becomes chorion