Human Development Flashcards

1
Q

starts about 24 hours after fertilization and continues as the embryo moves down the oviduct towards the uterus

A

Cleavage

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2
Q

the mammalian equivalent of the sea urchin blastula

A

Blastocyst

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3
Q

has a fluid-filled cavity, an inner cell mass that will actually form the baby

A

Human blastocyst

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4
Q

an outer layer of cells

A

Trophoblast

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5
Q

the organ that provides nourishment and oxygen to the embryo and helps dispose of its metabolic wastes.

A

Placenta

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6
Q

under way by 9 days after conception

A

Gastrulation

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7
Q

develop as attachments to the embryo and help support it.

A

Extraembryonic membranes

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8
Q

Extraembryonic Membranes

A
  1. Amnion
  2. Yolk sac
  3. Chorion
  4. Allontois
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9
Q

Developing as an extension of the yolk sacs

Extraembryonic Membranes

A

Allontois

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10
Q

outer part of the
embryo’s skin; continuous with
the amnion

A

Ectoderm

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11
Q

the embryo’s digestive tract; continuous with the yolk sac

A

Endoderm

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12
Q

the bulk of most other organs

A

Mesoderm

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13
Q

is filled with fluid, which protects the embryo

A

amniotic cavity

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14
Q

breaks just before childbirth and the amniotic fluid (“water”) leaves the mother’s body through her vagina.

A

amnion

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15
Q

remains small and produces the embryo’s first blood cells and its first germ cells, the cells that will give rise to the gamete-forming cells in the gonads.

A

Placenta

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16
Q

it forms part of the umbilical cord

A

Allantois

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17
Q

forms the embryo’s urinary bladder

A

Allantois

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18
Q

In a bird and reptiles, the ____ expands around the embryo and functions in waste disposal.

A

Allantois

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19
Q

lifeline between the embryo and the placenta

A

umbilical cord

20
Q

developed from the trophoblast and from mesoderm cells derived from the yolk sac

21
Q

outermost extraembryonic membrane

22
Q

cells in the chorion secrete a hormone called

A

human chorionic gonadotrophin (HCG)

23
Q

maintains the corpus luteum of the ovary during the first 3 months of pregnancy.

A

human chorionic gonadotrophin (HCG)

24
Q

contain embryonic blood vessels formed from mesoderm

A

Chorionic villi

25
# The chorionic blood vessels color red: (1) color blue: (2)
(1) absorb nutrients and oxygen (2) carry wastes away from the embryo
26
takes care of the embryo’s every need
Placenta
27
allows protective antibodies to pass from the mother to the fetus.
Placenta
28
A month-old human embryo is about ____ long
7mm (0.28in)
29
____________ about 9 weeks after fertilization
Fetus
30
the clear sac around the fetus is the _________
amnion
30
# First Trimester, A fetus is about ____ long has all of its organs and major body parts, including a disproportionately large head.
5.5 cm (2.2in)
31
# Identify the trimester - the somites have developed into segmental muscles and the bones of the back and ribs. - the limb buds have become tiny arms and legs with fingers and toes.
First Trimester
32
By the end of 1st trimester:
- the fetus looks like a miniature human being although its head is still oversized for the rest of the body. - the sex of the fetus is usually evident at this time.
33
# 2nd Trimester At 14 weeks, The fetus is now about ________ long
6 cm (2.4 in)
34
# Identify the trimester - Placenta takes over the task of maintaining itself by secreting progesterone rather than receiving it from corpus luteum - At the same time, the placenta stops secreting HCG and the corpus luteum no longer needed to maintain pregnancy, degenerates
2nd Trimester | 14 weeks
35
# 2nd Trimester At 20 weeks, the fetus is about ________ longs, weighs about ______
19 cm (7.6 in) & 1/2 kg (1lb)
36
# Identify the trimester - Face of an infant, complete with eyebrows and eyelashes - Its arms, legs, fingers and toes have lengthened - It also has fingernails and toenails and is covered with fine hair
2nd Trimester | 20 weeks
37
# Identify the trimester - By this time, the fetal heartbeat is readily detected, and the fetus usually is quite active - The mother’s abdomen has become markedly enlarged and she may often feel her baby move
Second Trimester
38
Because of the limited space in the uterus, the fetus flexes forward into the so-called ______
fetal position | (Second Trimester)
39
By the end of 2nd trimester:
the fetus eyes are open and its teeth are forming
40
# Identify the trimester A time of rapid growth as the fetus gains the strength it will need to survive outside the protective environment of the uterus.
Third Trimester
41
# Identify the trimester the fetus’ circulatory system and respiratory system undergo changes that will allow the switch to air breathing.
Third Trimester
42
# Identify the trimester The fetus gains the ability to maintain its own temperature and its bones begin to harden and its muscles thicken.
Third Trimester
43
# Identify the trimester - The fetus loses much of its fine body hair, except on its head - The head itself changes its proportions
Third Trimester
44
# Identify the trimester The fetus becomes less active as it fills the space in the uterus
Third Trimester
45
At birth, a typical baby is about ________ longs and weighs _________
50 cm (20in) & 2.7-4.5 kg (6-10lbs)