Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 30 > Embryonic Period - 15.1 > Flashcards

Embryonic Period - 15.1 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What do biologists divide prenatal birth into?

A

Three trimesters - three months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two main periods of prenatal development?

A

Embryonic period and Fetal period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What period is the embryonic period?

A

First two thirds of the trimester - first Eight weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens during the embryonic period?

A

*Cells divide and become redistributed
* Tissues and organs forms
* Structures that support and nourish embryo develop

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What period is the fetal period?

A

The remaining third of the first trimester and all the second and third trimesters - month weeks through to birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens during the fetal period?

A

Body grows rapidly and organs begin to function and coordinate to form organ systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is fertilzation?

A

The joining of male and female gametes (sperm and egg) to form a singe cell that has 46 chromosomes - 23 chromosomes from each parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is another name for fertilization?

A

Conception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How long does it take egg to reach uterus?

A

About 4 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When should the egg be fertilized to prevent it from losing its capacity to develop?

A

Within 12 or 24 hours of its released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Do all the sperms reach the egg?

A

No, some go to the wrong oviduct or are destroyed by the acidic environment of the vagina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the plasma membrane of the egg ?

A

Zona pellucida - clear layer of protein and carbohydrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What layer surrounds the zona pellucida?

A

Corona radiata - several jelly like layers of follicle cells that loosely adhere to one another - cells were a source of nourishment for the egg when it was an ovarian follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What allows the sperm to penetrate corona radiata and and zona pellucida?

A

The acrosome (head) that contains enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens when one sperm penetrates the egg?

A

The egg plasma membrane depolarizes, preventing other sperm from penetrating it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens within 12 hours of the sperm nucleus entering the egg?

A

The sperm cell nucleus and egg cell nucleus disappear - zygote - has 46 chromosomes, 23 from each parent cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens within 30 hours of being fertilized?

A

The egg begins to divide - cleavage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens when a zygote is a sphere of 16 cells?

A

Morula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When does morula reach the uterus?

A

Three to five days after fertilization?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the two different cell groups that form when the blastocyst becomes filled with fluid?

A

The trophoblast and the inner cell mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does the fluid that fills the blastocyst come from?

A

Diffuses from the uterus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the outer layer of the blastocyst?

A

Trophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the trophoblast develop into?

A

The chorion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What will the chorion develop into?

A

Develops to form part of the placenta (provides nutrience and oxygen, removes wastes from the developing fetus).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the group of cells that forms inside the blastocyst?

A

Inner cell mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does the inner cell mass develop into?

A

Develops into the embryo itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens between the fifth and seventh day after fertilization?

A

blastocyst attaches to the endometrium

28
Q

How does the trophoblast implant into the endometrium?

A

It secretes enzymes that digest some of the tissues and blood vessels of the endometrium

29
Q

What is implantation?

A

The nestling of the blastocyst into the endometrium

30
Q

When is implantation complete?

A

By the tenth of fourteenth day

31
Q

What hormone does the trophoblast secrete?

A

hCG - human chorionic gonadotropin

32
Q

What does hCG do?

A

It maintains the corpus luteum - secretes estrogen and progesterone continuously, maintaining the endometrium and preventing menstruation

33
Q

When does hCH production decline?

A

It declines to a low level at the end of four months - Corpus luteum is less important after the first trimester - placenta secretes enough estrogen and progesterone to maintain corpus luteum

34
Q

What happens during the second week?

A

A space forms between the inner cell mass and the trophoblast (amniotic cavity) - will fill with fluid where baby will develop

35
Q

What surrounds the amniotic cavity?

A

The amnion

36
Q

What happens as the amniotic cavity forms?

A

Inner cell mass flattens into the embryonic disk

37
Q

What supports the embryonic disk?

A

A short stalk that connects the blastocyst with the endometrium

38
Q

What are the three layers of the embryonic disk?

A

Endoderm, mesoderm, and ectoderm

39
Q

What is the process of forming these layers?

A

Gastrulation - primary germ layers

40
Q

What is the developing embryo called

A

Gastrula

41
Q

What marks the beginning of morphogenesis?

A

Gastrulation

42
Q

What is morphgenesis?

A

The series of events that form distinct structures in the developing organisms

43
Q

What is differentiation?

A

The cellular process that enables cells to develop a particular shape and perform a specific function - that are different from the functions of other cells

44
Q

Why are the primary germ layers important?

A

All the cells, tissues, and organs of the body are derived from them

45
Q

What occurs during the third and eighth week?

A

The organs form

46
Q

What occurs during the 3rd week?

A

A thickened band of mesoderm develops along the back of the embryonic disk - these cells will become the babies back - and come together to form the notochord
* notochord - basic framework of the skeleton

47
Q

How does the nervous system develop?

A

Develops from the ectoderm that is located just above the notochord

48
Q

How does the ectoderm form the CNS?

A

*Cells along the surface of the notochord begin to thicken
* Folds develop on each side of a groove on its surface
* Folds fuse and become a tube (neural tube) which develop into the brain and spinal cord

49
Q

When does the heart start beating?

A

On about the 18th day

50
Q

What happens in the fourth week?

A
  • Time of rapid growth and differentiation
  • blood cells form and fill with developing blood vessels
  • lungs and kidneys take shape
  • small buds (legs and arms appear)
  • Distinct head is visible (ears, eyes, and nose)
51
Q

What happens in the fifth week?

A
  • Head is very large compared to the body
  • Eyes open but they do not have eyelids or irises
  • Cells in the brain are differentiating very quickly
52
Q

What happens in the sixth week?

A
  • Brain continues rapid development
  • Limbs lengthen and slightly flex
  • Gonads start producing hormones that will influence the development of external genetelia
53
Q

What happens in the seventh and eight week?

A

*Embryo has distinct human characteristics - organs are formed - nervous system is starting to coordinate movement

  • Skeleton cartilage has formed
  • Eyes are well developed - eyelids close them
  • Nostrils are developing - plugged with mucus
  • External genetelia is developing

*Embryo is size of paper clip

54
Q

What are the extra embryonic membranes?

A

Allantonis, amion, chorion, and yolk sac

55
Q

What are the extra embryonic membranes responsible for?

A

Protection, nutrition, respiration, and excretion

56
Q

What is the amnion?

A
  • Transparent sac that develops from cells of the embryonic disk
  • it is penetrated only by the unbilical cord
  • amnion becomes filled with fluid (amioniotic fluid) - that protects baby from trauma and temperature fluctuations, allows freedom of movement, and prevents limbs from sticking to the body
57
Q

What is the allantois?

A
  • Forms the foundation of the umbilical cord
  • During the second month, most of the allantois degenerates
  • remainder becomes part of the urinary bladder
58
Q

What is the yolk sac?

A
  • Sac that is suspended from the abdominal area of embryo
  • contributes to the formation of the digestive tract and produces the first blood cells and the future egg or sperm cells
  • has no nutritive function
59
Q

What is the chorion?

A
  • Outermost membrane
  • encloses all the other extra embryonic membranes as well as the embryo
  • Forms the fetal portion of the placenta
60
Q

What establishes the beggininggs of the placenta?

A

The chorionic villi that extend into the uterine lining

61
Q

How is the embryo attached to the uterine wall?

A

By the placenta

62
Q

When is the placenta fully developed?

A

After about 10 weeks - it is now 600g

63
Q

When does the yolk sac shrink and the amniotic sac enlarge?

A

Newar the end of eighth weeks

64
Q

What does the umbillical cord contain?

A

Two arteries (transport oxygen depleted blood from fetus to placenta)
One vain (brings oxygen rich blood to the fetus)

65
Q

Why does the unbillical cord have natural twists?

A

Because the unbilical vein is larger than the arteries are

Biology 30 (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions