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MCAT Biology > Embryogenesis and Development > Flashcards

Embryogenesis and Development Flashcards

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1
Q

ampulla

A

widest part of fallopian tube; where fertilization occurs

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2
Q

acrosomal apparatus

A

tubelike structure formed when the sperm first comes in contact with the oocyte’s cell membrane; extends and penetrates said cell membrane

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3
Q

comical reaction

A

releases calcium ions that occurs after penetration of the sperm through the oocyte’s cell membrane; calcium ions depolarize cell membrane which prevents fertilization by two sperm and increases metabolic rate of newly formed zygote

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4
Q

zygote

A

egg plus sperm; unicellular

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5
Q

fertilization membrane

A

depolarized and impenetrable membrane of zygote

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6
Q

dizygotic (fraternal) twins

A

form from fertilization of two different offs released during one ovulatory cycle by two different sperm

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7
Q

monozygotic (identical) twins

A

form when a single zygote splits into two; the genomes are identical

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8
Q

conjoined twins

A

occur when a zygote incompletely divides

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9
Q

cleavage

A

rapid mitotic cell divisions; create embryo from zygote

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10
Q

indeterminate cleavage

A

results in cells that can still develop into complete organisms

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11
Q

determinate cleavage

A

result in cells with fates that are already determined; committed to differentiating into a certain type of cell

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12
Q

morula

A

solid mass of cells; several divisions into cleavage

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13
Q

blastulation

A

forms the blastula

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14
Q

blastula

A

hollow ball of cells with a fluid-filled inner cavity known as a blastocoel

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15
Q

blastocyst

A

mammalian form of blastula; consists of two cell groups: trophoblast and inner cell mass

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16
Q

trophoblast cells

A

surround the blastocoel; give rise to chorion and later the placenta

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17
Q

inner mass cells

A

protrude into blastocoel and form organism itself

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18
Q

chorion

A

extra embryonic membrane that develops into the placenta

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19
Q

chronic villi

A

microscopic like projections that penetrate mother’s endometrium; support maternal-fetal gas exchange

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20
Q

umbilical cord

A

embryo is connected to the placenta with this cord; consists of two arteries and one vein

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21
Q

umbilical vein and arteries

A

vein: carries freshly oxygenated blood from the placenta to the embryo
arteries: carry deoxygenated blood and waste to the placenta for exchange

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22
Q

yolk sac

A

supports the embryo until the placenta is functional; also the site of early blood cell development

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23
Q

allantois

A

involved in early fluid exchange between embryo and yolk sac

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24
Q

amnion

A

thin, tough membrane filled with amniotic fluid

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25
Q

gastrulation

A

generation of three distinct cell layers

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26
Q

gastrula

A

result of blastula being pushed together

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27
Q

archenteron

A

membrane invagination into the blastocoel which eventually becomes the gut

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28
Q

blastopore

A

opening of the archenteron which develops into the anus

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29
Q

primary germ layers

A

some cells migrate into what remains of the blastocoel to form these; include ectoderm, mesoderm and endoderm

30
Q

ectoderm

A

outermost layer; gives rise to integument, lens of the ye, nervous system and inner ear

31
Q

mesoderm

A

middle layer; develops into musculoskeletal, circulatory and most of the excretory systems; also gonads and muscular/connective tissues of the digestive/respiratory systems and the adrenal cortex

32
Q

endoderm

A

innermost layer; forms epithelial linings of the digestive and respiratory tracts, including lungs; also form pancreas, thyroid, bladder, distal urinary tracts and parts of the liver

33
Q

selective transcription

A

only the genes needed for a particular cell are transcribed

34
Q

induction

A

the ability of one group of cells to influence the fate of nearby cells

35
Q

inducers

A

chemical substances that diffuse from organizing cells to responsive cells to tell them what to be

36
Q

neurulation

A

development of the nervous system

37
Q

notochord

A

rod of mesodermal cells that forms a primitive spine

38
Q

neural fold, neural groove, neural tube, neural crest cells

A

neural fold- surround neural groove
neural tube- formed when neural folds grow together; gives rise to CNS
neural crest cells-found at the tip of the neural folds; migrate outward to form PNS

39
Q

teratogens

A

substances that interfere with development, causing defects or even death; effects depend on the embryo itself, route of exposure, length of expresser, rate of placental transmission of teratogen and exact identity of teratogen

40
Q

specification

A

cell is reversibly designated to a specific cell type

41
Q

determination

A

commitment of a cell to having a particular function; irreversibly committed to a certain cell lineage; may occur during cleavage or due to the secretion of specific molecules from nearby cells

42
Q

morphogens

A

molecules that may cause nearby cells to follow a particular developmental pathway

43
Q

differentiation

A

changing the structure, function and biochemistry of a cell to match its determined cell type

44
Q

stem cells

A

have not yet differentiated or give rise to other cells that will differentiate

45
Q

totipotent stem cells

A

include embryonic stem cells; can differentiate into any cell type

46
Q

pluripotent stem cells

A

cells that can differentiate into any cell type except those found in the placental structures

47
Q

multipotent stem cells

A

can differentiate into multiple types of cells within a particular group

48
Q

competent

A

cell must be able to respond to inducing signal

49
Q

autocrine signals

A

act on the same cell that secreted the signal in the first place

50
Q

paracrine signals

A

act on cells in the local area

51
Q

juxtacrine signals

A

cell directly stimulating receptors of the adjacent cell

52
Q

endocrine signals

A

involve secreted hormones that travel through the bloodstream to a distant target tissue

53
Q

growth factors

A

peptides that promote differentiation and mitosis in certain tissues

54
Q

reciprocal development

A

most tissues will be exposed to multiple inducers during the course of development

55
Q

apoptosis

A

programmed cell death

56
Q

apoptotic blebs

A

self-contained protrusions; result of apoptosis

57
Q

apoptotic bodies

A

v small particles that can be digested by other cells

58
Q

necrosis

A

process of cell death in which a cell dies as a result of an injury; internal substances are leaked, causing irritation or even an immune response

59
Q

senescence

A

biological aging; occurs when molecular/cellular changes accumulate; may be due to shortened telomeres

60
Q

fetal hemoglobin (HbF)

A

has a higher affinity for oxygen than does maternal oxygen because the mom has higher O2 concentration than the fetus

61
Q

umbilical arteries

A

carry blood away from the fetus and towards the placenta (deoxygenated blood)

62
Q

umbilical vein

A

carries blood toward the fetus from the placenta (oxygenated blood)

63
Q

fetal lungs and liver

A

don’t function before birth; oxygen exchange instead occurs at the placenta; liver functions carried out by mother and placenta

64
Q

shunts

A

three fetal shunts carry blood away from the lungs and liver until birth

65
Q

foramen ovale

A

one way valve that connects the right atrium to the left atrium; allows blood entering the right atrum from the inferior vena cava to flow into the left atrium instead of the right ventricle, therefore being pumped through the aorta into systemic circulation directly; works because blood pressure is higher in the right side of the heart than the left side in the fetus

66
Q

ductus arteriosus

A

shunts leftover blood from the pulmonary artery to the aorta; pressure differential pushes blood through this opening and into systemic circulation

67
Q

ductus venosus

A

shunts blood retuning from the placenta directly to the inferior vena cava; bypasses liver

68
Q

first trimester

A
  • major organs begin to develop
  • heart begins to beat at app. 22 days
  • soon after, eyes, gonads, limbs and liver start to form
  • by week 7, skeleton begins to harden from cartilage to bone
  • by end of week 8, most organs have formed, brain is fairly developed and embryo is known as a fetus
69
Q

second trimester

A
  • fetus undergoes lots of growth
  • begins to move around
  • face takes on human appearance
  • toes and fingers elongate
  • 30-36 cm long
70
Q

third trimester

A
  • rapid growth and brain development
  • antibodies are transported for protection
  • growth rate slows in 9th month and baby stops moving as much
71
Q

parturition

A

vaginal childbirth; accomplished by rhythmic contractions of uterine smooth muscle; coordinated by prostaglandins and oxytocin

72
Q

three basic phases of birth

A
  • cervix thins out and amniotic sac ruptures
  • strong uterine contractions result in birth of fetus
  • placenta and umbilical cord (afterbirth) are expelled

MCAT Biology (6 decks)

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