ch.3 embryology week 1

Question 1

embryology and its importance

Answer 1

study of the origin and development of an individual.
-importance: for understanding the normal relationship of adult structures.

Question 2

prenatal period

Answer 2

time between conception and birth

Question 3

what are the portions of the prenatal period

Answer 3

-embryonic: first 8 weeks, crucial for development
-fetal period: remaining 30 weeks; body size increases

Question 4

what does the adult body basic plan include?

Answer 4

-skin
-outer body wall: trunk musculatore
-body cavities and inner tube

Question 5

what are the key events of week 1:

Answer 5

-fertilization and zygote formation
-cleavage and blastocyst formation
-beginning of implantation

Question 6

week 2 key events

Answer 6

-completion of implantation
-formation of embryonic disc
-amniotic sac and yolk sac

Question 7

week 3 key events:

Answer 7

• gastrulation
  -neural tube formation
  -mesoderm differentiation

Question 8

week 4 key events:

Answer 8

-folding embryo into normal shape
-derivates of germ layer

Question 9

week 5 key events:

Answer 9

all development processes occur by week 5

Question 10

week 1: fertilization
-how does it start?

Answer 10

-release of an immature egg

Question 11

what is the term for an immature egg?

Answer 11

oocyte

Question 12

where does fertilization occur?

Answer 12

in the lateral 1/3 of the uterine tube.
egg needs to be cast off and meet sperm

Question 13

how long does healthy sperm last?

Answer 13

up to five days

Question 14

what does semen contain

Answer 14

enzymes, nutrients and other compounds that promote healthy sperm and aid in movement

Question 15

female infertility and causes

Answer 15

-accounts 30%
-hormonal imbalances causing ovulation issues
-blockages in uterine tubes
-infections in the lining of the uterus
-endometriosis and uterine fibroids.

Question 16

where does the sperm bind to the oocyte during fertilization?

Answer 16

bind to receptors on the zona pellucida (external membrane), around the oocyte

Question 17

once one sperm binds

Answer 17

all other sperm are rejected

Question 18

the sperm head contains

Answer 18

paternal genetic info

Question 19

what is the outcome of fertilzation?

Answer 19

production of a zygote (fertilized egg)

Question 20

week 1: cleavage and blast
-once the zygote divides, it makes

Answer 20

two daughter cells called blastomeres

Question 21

cleavage

Answer 21

the process of creating blastomeres.
-creates large number of cells that become the building blocks of the embryo.

Question 22

week 1: cleavage and blast
-what is a morula

Answer 22

a solid ball of cells
-made by day 3

Question 23

week 1: cleavage and blast
-compaction?

Answer 23

the tight alignment of morula cells, allows greater cell to cell interaction; a pre-req for embryonic formation

Question 24

week 1: cleavage and blast
-what happens on day 4?

Answer 24

the morula reaches the uterus and undergoes a series of changes:
-fluid from the uterus enters the morula and collects between the blastomeres= generates a central cavity
* makes a blastocyst

Question 25

week 1: cleavage and blast
-what is a blastocyst?

Answer 25

new fluid filled structure (day 4)
almost ready for implantation

Question 26

week 1: cleavage and blast
what happens on days 4-7 to the blastocyst’s structure?

Answer 26

-trophoblast and embryoblast forms

Question 27

week 1: cleavage and blast
-describe trophoblast and embryoblast

Answer 27

-trophoblast: an outer cell layer surrounding the blastocyst cavity. helps form the placenta
-embryoblast: inner cell mass. helps form the embryo.

Question 28

week 1: cleavage and blast
-how long does the blastocyst stage last? and where does it go?

Answer 28

-around three days. days 4-7.
-during that time the blastocyst is free. but around day 6 it starts to burrow into the uterine wall

Question 29

week 1: beginning of implantation
-when does implantation start and how long does it take?

Answer 29

-starts on day 6 and takes about a week to complete

Question 30

week 1: beginning of implantation
-what is overall what happens during implantation

Answer 30

the trophoblast erodes the uterine lining until the entire blastocyst becomes embedded within the structure
-the projections of the trophoblast tat erode the maternal lining allow the blastocyst to penetrate itself inside .

Question 31

ectopic pregancy:

Answer 31

implantation occurs somewhere else, no good epithelium.