MCAT Biology Ch5: Embryology Kap Flashcards

1
Q

cleavage

A

moving from fallopian tube => uterus to implanation => UNDERGOES RAPID MITOTIC CELL DIVISION (rapid)

first one creates an embryo

although several rounds of mitosis, total size of embryo remains unchanged during first few divisions

cells inc. two ratios: nuclear to cytoplasmic and SA to vol. => cells inc. area for gas nutrient diffusion relative to overall volume.

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2
Q

indeterminate

A

results in cells that can still develop into complete organisms.

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3
Q

determinate

A

cells whose fates are determined

differentiating into a certain type of cell

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4
Q

differentiating

A

results in CERTAIN type of cell

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5
Q

two types of cleavage

A

indeterminate or determinate

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6
Q

1st, 2nd, 3rd cleavages occurs

A

32, 60, 72 hours

at this point, 8 celled embryo completed to uterus

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7
Q

morula (cleavage)

A

several division occurs, the embryo becomes a solid mass of cells

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8
Q

blastulation (cleavage)

A

after morula

forms blastula

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9
Q

blastula (cleavage)

A

when implants outside of uterus => ectopic pregnancy (most in fallopian tube) => inviable => if embryo doesn’t spon. abort => tube may rupture => hemorrhaging

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10
Q

blastocoel (cleavage)

A

hollow, fluid-filled inner cavity of blastula

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11
Q

blastocyst (cleavage)

A

mammalian blastula

consists of two noteworthy cell groups: trophoblast and inner cell mass

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12
Q

two cell groups of blastocyst (cleavage)

A

trophoblast and inner cell mass

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13
Q

trophoblast (cleavage)

A

surround blastocoel and give rise to chorion, and later placenta

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14
Q

inner cell mass (cleavage)

A

protrudes into blastocoel and gives rise to organism itself

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15
Q

early developmental stages

A

cleavage, implantation, gastrulation, neurulation

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16
Q

implantation

A

blastocyst in uterine wall => blastocyst implants endometrium

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17
Q

endometrium (implanation)

A

prepared in anticipation, where blastocyst implants here

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18
Q

progesterone (implanation)

A

steroid hormone promote proliferation of (endometrial) mucosal layer to help embryo implact

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19
Q

key step of implanation

A

embryonic cells secrete enzymes that burrow into endometrial lining to allow for implantation => form connection to maternal circulation for nutrient and gas exchange

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20
Q

implantaton like tree

A

seed (embryo) into ground (endometrium) => make sure soil is fertile (progestrone to endometrium)

shovel to plant seed in ground (proteolytic enzyme allow embryo to settle in uterine wall)

tree generate roots (placenta) => gas and nutrient exchange w/ soil (endometrium)

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21
Q

gastrulation

A

generation of 3 distinct cell layers

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22
Q

gastrulation in sea urchins

A

begins w/ small invagination in blastula => cells continue moving toward invagination => elimination of blastocoel => gastrula

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23
Q

gastrula (gastrulation )

A

two-layered cup form after elimination of blastcoel

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24
Q

endoderm (gastrulation)

A

inner cell layer

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25
Q

ectoderm (gastrulation )

A

outer cell layer

cells migrate over the neural tube and crests to cover rudimentary nervous system

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26
Q

archenteron (gastrulation )

A

cavity created by deep invagination

later develops into gut

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27
Q

blastophore (gastrulation )

A

opening of archenteron

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28
Q

deuterostomes (gastrulation )

A

in humans, blastopore develops into anus

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29
Q

protostomes (gastrulation )

A

blastopore dvelops into the mouth

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30
Q

mesoderm (gastrulation)

A

eventually some cells also migrate into area between ectoderm and endoderm

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31
Q

parts of ectoderm (gastrulation )

A

attract o derm

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32
Q

parts of mesoderm (gastrulation)

A

“means” o derm, we get from place to place in world

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33
Q

part of endoderm (gastrulation)

A

“endernal” orgams

long tubes running from mouth to anus (digestive tract), organs attached to it (accessory organs of digestion)

gives rise to the lungs

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34
Q

cleavage

A

single cell zygote => several mitosis occur (total size of embryo same) => several division becomes morula => blastulation

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35
Q

embryonic stem cells

A

derived from portion of very early stage emybryo => entire body (retain pluripotent ability to form any cell type)

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36
Q

cell fate

A

less than a week after human egg fertilized => developing embryo (blastocyst which only an outer cell mass, in preg. becomes placenta, and inner cell mass, which becomes fetus) => in womb, cells multiply

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37
Q

making embryonic cells

A

create by remove inner cell mass from blastocyst

ICM on plate containing feeder cells => attaches => few days, new cells grow out of ICM => form colonies

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38
Q

two criterias of ES cells

A
  1. display markers
  2. undergo several generations of cell division, or passages, => show that they constitute a stable, or immortalized, cell line
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39
Q

selective transciption of Somatic cells DNA (gastrulation)

A

of the genome (only genes for eye are tunred on in the eye.

often related to concept of induction => ability of certain group of cells to influence the fate of other nearby =>

40
Q

inducers (gastrulation)

A

selective transcription process mediated by these chem, substances

passed from organizing cells to responsive cells

41
Q

neurlation

A

once three germ layers => DEVELOPMENT OF NERVOUS SYSTEMS CAN BEGIN

42
Q

nervous system derived from neurulation

A

cells migrate inward => notochord => induce group of ectodermal cells to slide inward to form neural folds => surround neural grove => grow together one another => neural tube => CNS

43
Q

notochord

A

rod of mesodermal cells, forms along the long axis of organism

induce group of ectodermal cells to slide inward to form neural folds

44
Q

neural folds

A

induce group of ectodermal cells to slide inward to form

surround neural groove

45
Q

neural tube

A

neural folds grow toward one another until they fuse into this

46
Q

neural crest cells

A

tip of each neural fold

cells migrate outward to form PNS (sensory ganglia, autonomic ganglia, adrenal medulla, Schwann cells

47
Q

fetal respiration

A

nutrient and gas exchange w/ maternal ciruclation necessary part of fetal development

48
Q

two structures of fetal development

A

placenta and umbilical cord

49
Q

placenta

A

primarily formed from chorion

organ where nutrient, gas, and waste exchanges occur; simplest way is through diffusion in fetus

crucial that no mixing of maternal and fetal blood (may have diff. bloods) => diffusion

higher P(oxygen) in maternal blood than in fetal blood

waste materials and CO2 move in opposite direction

endocrine organ, since produces progesterone, estrogen, and human chorionic gonadotropin, all essential for maintaining pregnancy (266 days)

50
Q

chorion

A

placenta primarly formed from an extra-embryonic membrane

develops from trophoblast cells

outermost embryonic layer, completely surrounds the other membrane, providing added level of protection

51
Q

human umbilical cord

A

and vessels provide attachment to chorion and nutrition for fetus

surround by jellylike matrix

initial connection of fetus to mother

52
Q

three extra embryonic membranes of fetal respiration

A

allantois, amnion, yolk sac

53
Q

allantois

A

surround by amnion

54
Q

amnion

A

thin, tough membrane filled w/ amniotic fluid

55
Q

amniotic fluid

A

shock absorber during pregnancy and labor

56
Q

yolk sac

A

site of blood vessel development

57
Q

chorionic villi

A

eventually grow into placenta

support maternal fetal gas exchange

58
Q

amniocentesis

A

aspirating amniotic fluid by inserting a thin needle into amniotic sac

59
Q

amniotic fluid

A

contains fetal cells

can be examined for chromosomal abnormalities and sex determination

can result in genetic aberrations like Down Syndrome

60
Q

fetal hemoglobin Hb-F

A

fetal blood cells equipped w/ this, which exhibit greater affinity for oxygen than does maternal (adult) hemoglobin, known as Hb-A

61
Q

Hb-A

A

maternal (adult) hemoglbin

62
Q

placenta barrier

A

immune protection

foreign particles and bacteria too large to cross by diffusion, however not the case for virus, alcohol, toxins

63
Q

two important organs that are underdeveloped in fetus and rely on placenta

A

lungs and liver

64
Q

fetus lungs

A

not able to oxygenate circulating blood

are suspended in aq. amniotic fluid => no air to take in

oxygen comes from maternal circulation => diffuse through placenta vessel

65
Q

two fetal shunts keep blood away from LUNGS by rerouting blood w/in heart

A

foramen ovule and ductus arteriosus

66
Q

foramen ovule

A

connects right and left atria

blood entering superior vena cava => right atrium => left atrium => out of aorta into systemic circulation

pressure differential:
-pressure higher in right atrium since will spon. down pressure gradient

gradient reverse in adults => forman ovale shut after birth

67
Q

ductus arteriosus

A

present to shunt leftover blood from pulmonary artery to aorta

works like forman ovale => pressure right fetal heart is higher that that of the left

patent ductus arteriosus (PDA) => stays open after birth
-direction of blood flow through PDA will be determined by relative resistance of pulmonary and systemic circulation => if cont. => neonate will turn blue since deoxygenate venous blood bypasses lung and mixes w/ oxygenated blood being pump to body through aorta

68
Q

fetal liver

A

underdeveloped, can’t fully able to carry out adult taks in utero

since placenta capable of pitching during gestation, blood returning from placenta via umbilical vein is rerouted to inferior vena cava via this

even though needs a lot of O2, it prevents from stealing oxygen from designated from rest of the body => liver has own reserves from arteries leaving the heart.

69
Q

umbilical arteries

A

carry blood away from fetus

carry deoxygenated blood

70
Q

umbilical vein

A

blood toward the fetus

carry oxygenated blood

71
Q

human pregnancy

A

266 days

divided into 3 trimesters

72
Q

gestation rule

A

larger the animal, longer the gestational period, and fewer the offspring

73
Q

first trimester of pregnancy

A

end of third month:

1. fetus abou 9 cm long

74
Q

first trimester of pregnancy (first week)

A

major organs develop

  1. heart beats to beat approx. 22 days
  2. eyes, gonads, limbs, and liver start to form
75
Q

first trimester of pregnancy (five weeks)

A
  1. embryo is 10 mm length
76
Q

first trimester of pregnancy (six week:)

A
  1. 15 mm length
77
Q

first trimester of pregnancy (seventh week)

A
  1. by this time, cartilaginous skeleton begins to harden into bone
78
Q

first trimester of pregnancy (eight week)

A
  1. most organs have formed
  2. brain fully developed
  3. embryo = fetus
79
Q

first trimester of pregnancy (3rd month)

A

fetus about 9 cm long

80
Q

second trimester of pregnancy

A

fetus undergoes amount of growth

begins to move around in amniotic fluid

toes and fingers elongate

end of sixth month - fetus measures 30 to 36 cm long

81
Q

third trimester of pregnancy

A

7th and 8th month = cont. rapid growth and further brain development

9th month - antibodies transported by highly selective active transport from mom to fetus for protection against foreign matter, in prep outside of womb

growth rate slows and fetus becomes less active since less room to move about

82
Q

vagina childbirth

A

by rhythmic contractions of uterine smooth muscle, coordinated by prostaglandins and peptide hormone oxytocin

83
Q

3 basic phases to childbirth

A
  1. cervix thin out and amniotic sac ruptures (water breaking)
  2. strong uterine contraction => birth of fetus
  3. placenta and umb. cord are expelled (afterbirth)
84
Q

monozygotic twins

A

identical genomes because both originate from indeterminately cleaved cells of same embryo

85
Q

embroyo w/ blasted out cavity

A

this is blastula

86
Q

adrenal cortex

A

derived from mesoderm

87
Q

adrenal medulla

A

derived from ectoderm (since contains some nervous tissue)

88
Q

spinal bifida

A

failture of neutral tube to close

89
Q

zygote

A

undergoes several rapid divisions -> determinate cleavage

90
Q

indeterminate cleavage

A

generation of identical twins

91
Q

gasturalation

A

neuralation occurs during this

92
Q

fetal respiration

A

occurs in placenta and not in developing lungs

93
Q

ductus venosus

A

since placenta capable of pitching during gestation, blood returning from placenta via umbilical vein is rerouted to inferior vena cava via this

even though needs a lot of O2, it prevents from stealing oxygen from designated from rest of the body => liver has own reserves from arteries leaving the heart.

94
Q

ductus venosus

A

fetal shunt of liver

95
Q

fetal circulation contains 3 shunts

A

ductus venosus, foramen ovale, ductus arteriosus

96
Q

gestation

A

consists of three trimesters of 3 months each