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Anatomy > Week 2 Embryology 1 > Flashcards

Week 2 Embryology 1 Flashcards

1
Q

Gametogenesis

A

Formation of gametes (oocyte, sperm)

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2
Q

Gametes

A

Oocyte (female)
Sperm (male)
Half regular DNA content
Formed by either spermatogenesis or oogenesis through meiosis

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3
Q

What we use to make human beings

A

Gametes

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4
Q

Spermatogenesis

A

Formation of Sperm

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5
Q

Oogenesis

A

Formation of oocyte (egg)

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6
Q

Chromosomes

A

Human somatic cells contain 23 pairs of chromosomes - 46 total
22 pairs autosomes
One pair sex chromosomes

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7
Q

Autosomes

A

Contain genetic information for most human characteristics. A pair of similar autosomes are called homologous chromosomes.
22 pairs

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8
Q

Homologous chromosomes

A

A pair of similar autosomes (functionally the same)

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9
Q

Ploidy

A

Number of chromosomes

Human cell has 46 chromosomes

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10
Q

N

A

amount of DNA

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11
Q

2N

A

Dipoid

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12
Q

1N

A

Haploid (gamete)

1/2 number of paired chromosomes

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13
Q

How many chromosomes humans have

A

46, 23 pair

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14
Q

In normal cell, gamete has how much DNA?

A

1N

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15
Q

Gametogenesis

A

Begins with meiosis
Produces secondary oocytes in female
Produces sperm in male
Gametes contain 1/2 number of paired chromosomes and are called haploid (1N)

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16
Q

How to decrease to 1/2 the chromosomes

A

Meiosis

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17
Q

Meiosis I

A

Meiosis results in the formation of gametes (sex cells)

Homologous chromosomes are separated after synapsis and crossing over occurs

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18
Q

Meiosis II

A

Sister chromatids are seperated in a sequence of phases that resembles mitosis

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19
Q

Sister chromatids aka

A

Duplicated chromosome

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20
Q

Meiosis starts with this

A

Duplicated chromosome (aka sister chromatids)

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21
Q

Chromatid

A

One of the two strands of a chromosome joined together by a centromere
In Meisosis II, this seperates

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22
Q

Chromosomal Crossover

A

An important step in genetic recombination in which two chromosomes, normally homologous pair up and exchange DNA

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23
Q

Independent Assortment

A

Shuffling of genes

Increases variation and is heritable

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24
Q

_N at start of Meiosis 1, Prophase 1

A

4N

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25
Q

Spermatogenesis

A

Diploid cells that reside in the testes
Each one first divides by mitosis to make an exact copy of itself called a primary spermatocyte first
Then undergo meiosis and ultimately produce haploid cells called spermatids

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26
Q

Spermatogonia

A

Parent or stem cells that produce sperm

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27
Q

Primary spermatocyte

A

Sperm first divides by mitosis to make an exact copy of itself

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28
Q

Spermatids

A

When spermatocytes undergo meiosis they produce these haploid cells (23 chromosomes)
Lose much of their cytoplasm and grow long tail called flagellum

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29
Q

Sperm

A

22 autosomes
X or Y chromosomes
From a single spermatocyte, 4 new sperm are formed.

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30
Q

Acrosomes

A

Hydrolytic enzymes in sperm that punch hole in egg

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31
Q

Oocyte

A

*Secondary
The gamete produced
22 autosomes and one X chromosome
Parent cells called oogonia and reside in ovaries

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32
Q

Oogonia

A

Parent cells that produce oocytes and reside in the ovaries

Oogonia start process of meiosis and form primary oocytes prior to birth. Arrested in Prophase 1 until puberty

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33
Q

Meiosis 1 Oogenesis

A

End of meiotic division, two cells are produced
Division of cytoplasm is unequal
Secondary oocyte receives bulk of cytoplasm and is arrested in Metaphase II
The second cell is called a polar body

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34
Q

Polar body

A

The second cell, only receives a tiny bit of the cytoplasm

Nonfunctional cell and eventually degenerates

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35
Q

If secondary oocyte is not fertilized

A

(24-36 hours after ovulation)

it degenerates while arrested in metaphase II

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36
Q

If secondary oocyte is fertilized

A

Finishes the process of meiosis. Two cells are produced and cytoplasm is unequal. The cell with very little cytoplasm becomes another polar body

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37
Q

Ovum

A

The cell that receives the majority of the cytoplasm and can be fertilized

38
Q

Aneuploidy

A

Total chromosome number not equal to 46

39
Q

Congenital defect

A

Things that can go wrong

  • Mutations of genes
  • Abnormalities of chromosome division
  • numerical errors (too many or too few chromosomes) Results in aneuploidy
  • Structural errors
40
Q

Nondisjunction

A

Process of separation of homologous chromosome pairs fails

  • *sorting problem, in Meiosis 1 or 2
  • leads to abnormal chromosome number
  • too many (trisomy) or too few (monosomy)
41
Q

Trisomy

A

Too many copies of a chromosome
This type of disorder is named for chromosome involved
Process of separation of homologous chromosome pairs fails

42
Q

If nondisjunction occurs in Meiosis I

A

2/4 have trisomy

2/4 have monosomy

43
Q

If nondisjunction occurs in Meiosis II

A

2/4 are normal
1/4 trisomy (n+1)
1/4 monosomy (n-1)

44
Q

Down syndrome

A

Trisomy 21

45
Q

3 most common Autosomy

A

21, 18 and 13

46
Q

Klinefelter syndrome

A

47 XXY

Males. Tall, masculine features not as developed

47
Q

Turner’s syndrome

A

45 XO
Female. Monosomy
Treatable with estrogen

48
Q

47, XYY karyotype

A

? ‘syndrome’ because phenotype is normal

Male with 2 Y chromosomes, appear to be normal, fertility might be an issue, gametes without right number

49
Q

Offspring of Older Women

A

Higher incidence of chromosomal abnormalities
Prolonged dormancy of oocytes. Dormant since 5th month in utero
Incidence of trisomy 21 increases
Primary cause is maternal meiotic nondisjunction

50
Q

Primary cause of increased trisomy 21 with advanced maternal age

A

Maternal meiotic nondisjunction

Prolonged dormancy of oocytes

51
Q

Offspring of Older Men

A

Less of an issue with men, but some evidence of reduced fertility and possible increase in cancer and schizophrenia

52
Q

Problems with Chromosome Structure

A

Breakage (radiation or chemical teratogens)
Reciprocal and unbalanced translocations
Deletions
Duplications

53
Q

Teratogens

A

External agents - extrinsic to the fetus - that produce developmental malformations
Critical period is 3-8 weeks

54
Q

Potential Teratogens

A 
Radiation
Prenatal infections
Temperature extremes
Prescription drugs/dietary supplements
Recreational drugs - esp alcohol
Enviro toxins (lead, mercury)
Maternal malnutrition or disease
Mechanical forces (ex. IVF)
55
Q

4 reasons for teratogen variation

A
  1. Concentration and method of teratogen delivery
  2. Timing of exposure
  3. Variation in susceptibility due to genetic variation
  4. Synergistic interactions between the teratogen and other compounds (ex. what else you are taking)
56
Q

Secondary Oocyte

A

Only this one has potential to be fertilized (about 14 days)
This is ovulated
Corona radiata and the zona pellucida form protective layers around secondary oocyte

57
Q

Zona pellucida

A

Glycoprotein coat, receptors to help sperm identify and for protection

58
Q

Fertilization

A

Two gametes fuse to form a new cell containing genetic material derived from both parents
Restores the diploid number of chromosomes
Determines the sex of the organism
Initiates cleavage
Occurs in the widest part of uterine tube

59
Q

The Ampulla

A

Widest part of the uterine tube

Where fertilization occurs

60
Q

During Fertilization

A

Millions of sperm cells are deposited in female reproductive tract during intercourse
Only few hundred have chance at fertilization, only first to enter gets to fertilize

61
Q

Sperm at Fertilization

A

Hundreds try to get in, one wins. When one gets in, electric shock sent out to others and then receptors are taken away.

62
Q

Phase 3

A

Sperm head and tail enter oocyte

Second meiotic division with production of second polar body

63
Q

of weeks in pregnancy

A

Dated at 38 weeks, occurs between fertilization and birth

Dated at 40 weeks because include since last period

64
Q

Pre-embryonic Period

A

The first 2 weeks of development when the zygote vecomes a spherical, multicellular structure

65
Q

Embryonic Period

A

3-8 weeks of development during which all major organ systems appear
**CRITICAL time period

Major events of embryogenesis occur now

66
Q

3 major events of embryogenesis

A
  1. Cleavage
  2. Gastrulation
  3. Organogenesis
67
Q

Cleavage

A

Major event of embryogenesis

Division of zygote (fertilized egg) & formation of blastocyst

68
Q

Gastrulation

A

Major event of embryogenesis

Formation of 3 germ layers

69
Q

Organogenesis

A

Germ layers differentiate so as to give rise to all organs in the human body

70
Q

Embryo leaves zona pellucida

A

when it is a blastocyst at the end of Cleavage

71
Q

Fetal Period

A

Weeks 9-38
Fetus continues to grow
Organs increase in complexity
*can have abnormalities but less severe than weeks 3-8

72
Q

Cleavage

A

Shortly after fertilization, zygote begins to undergo a series of divisions
Divisions increase number of cells, but remains the same size
During each succeeding division, the cells are smaller and smaller
Cells at this stage are exactly alike

73
Q

Blasto

A

build

74
Q

Osteoblast

A

Build bone

75
Q

Morula

A

After the third cleavage, cells are tightly compacted into a ball
Means blackberry
If you took it out, it could grow the exact same thing

76
Q

Embryoblast

A

Inner cell mass

*builds the embryo

77
Q

Blastocyst cavity

A

Cavity gives space to grow and change

78
Q

Trophoblast cells

A

Outer cell mass
*will form part of the placenta
Part comes from moms uterus

79
Q

Blastocyst 3 parts

A
  1. Inner cell mass
  2. Blastocyst cavity
  3. Trophoblast cells
80
Q

Twinning

A

A. Cleavage of early embryo
-two blastocysts = monozygotic twins. Split early so have two placentas
B. Splitting of ICM
-one trophoblast so they share same placenta, causes more problems
C. Incomplete division of ICM
-Monozygotic where inner cell doesn’t split

81
Q

Conjoined twins

A

Occurs when inner cell doesn’t split in cleavage
Incomplete division of monozygotic twins
Extent of bridging is variable
Due to secondary fusion of ICM or development of 2 primitive streaks

82
Q

Implantation

A

First week after fertilization, blastocyst enters the lumen of the uterus
Zona pellucida around blastycyst begins to break down as blastocyst prepares to invade the endometrium
Implantation is the process by which the blastocyst burrows into and embeds within the endometrium

83
Q

Embryoblast

A

Embrionic stem cells

Must have trophoblast to use

84
Q

What attaches to wall in uterus

A

Trophoblast

85
Q

Ectopic Pregnancy

A

Implantation of blastocyst outside the uterine cavity
Can be predisposed by conditions that have caused inflammation and scarring of the uterine tubes (endometriosis, PID)
Can survive, just need C-section to get out

86
Q

What day does implantation occur?

A

Day 7

87
Q

Second opportunity for cellular differentiation

A

Implantation

88
Q

3 parts of Implantation

A
  1. Trophoblast cells differentiate
  2. Embryoblast cells differentiate
  3. Two cavities form
89
Q

2 layers in second week

A
  1. Epiblast

2. Hypoblast

90
Q

Cytotrophoblast and Syncytiotrophoblast

A

Tasked with invading. Find glands (energy) and find blood supply.
Will set up placenta

91
Q

hCG

A

Human chorionic gonadotrophin

Signals to the ovary to continue to secrete hormones to maintain the pregnancy

92
Q

Extraembryonic (XE) Mesoderm

A

Gives mechanical and trophic support

More spaces begin to form –> a larger cavity (coelom)

Anatomy (9 decks)

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