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Endocrine and Reproductive system > Human embryonic development > Flashcards

Human embryonic development Flashcards

1
Q

what is the pre-embryonic period

A

fertilisation of egg to end of 3rd week of development

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2
Q

what is embryonic period

and what is formed

A 
organogenesis - 4-8 weeks 
the three germ layers are formed 
ectoderm 
mesoderm 
endoderm 
main organs established 
sometimes this period includes pre embryonic stage so first 8
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3
Q

what is the fetal period

A

beginning of 3rd month to brith
period of maturation
no general agreement of beginning or end of this period

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4
Q

in what weeks of development if the embryo not susceptible to any harmful substance

A

2 weeks

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5
Q

when is the embryo most sensitive

A

1st trimester - congenital malformations

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6
Q

gametogenesis

A

production of male and female gametes or sec cells from primordial germ cells via meiotic division in the gonads
spermatogenesis
oogenesis

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7
Q

principle goals of gametogenisis

A

Gametogenesis reduces the chromosome number of the games fro diploid ( 23 paris- 46) to haploid ( 23 unpaired)

Gametogenesis results to an enhanced genetic variability in the gametes through a random recombination of genetic materials on homologous maternal and paternal chromosomes

Spermatogenesis does not start in the male until puberty - occurs in the seminiferous tubules of the testes

Oogenesis starts from fetal life in the female - occurs in the ovary and ocmpleted at puberty

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8
Q

what is a stem cell

A

undifferentiated cell that has ability to form specialised cell types - either embryonic or adult stem cells. Embryonic stem cells are pluripotent while adult stem cells are multipotent

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9
Q

what cell
ability to form all mature cell types in the body except placenta and extraembryonic cells. ( can form blood ) It cannot form a whole organism

A

pluripotent cell

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10
Q

ability to form more than one closely related mature cell types in the body but not as varied as pluripotent eg cord blood, bone marrow stem cells from erythrocyte , leukocyte and platelet - only form blood related cells
what cell

A

multipotent

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11
Q

has ability to form all differentiated cell types in the body including the placental and extraembryonic membrane cells. It could from a whole organism eg a zygote and first few generations of Blastomeres - form whole
what cell

A

totipotent

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12
Q

where does fertilisation occur

A

ampullary region of the uterine tube ( oviduct)

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13
Q

Phase 1 - penetration of the corona radiata
Phase 2 - penetration of the zona pellucida
Phase 3 - fusion of the oocyte and sperm cell membranes

are the 3 phases of what

A

fertilisation

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14
Q

what is capacitation

A

a sperm conditioning process within the female reproductive tract ( uterine tube) in prep for fertilisation in the ovum. Involves epithelial interactions between the sperm and the mucosal surface of the uterine tube. Only capacitated sperm can pass through the corona cells and undergo the acrosome reaction

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15
Q

what is the acrosome reaction

A

sperm with zona pellucida of oocyte - release of enzymes to penetrate cona pellucida

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16
Q

when the sperm makes contact with the plasma membrane of the oocyte this leads to release of lysosomal enzymes from the cortical granules in the plasma membrane doing what

A

makes it impenetrable for the rsperm - protection of polyspermy

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17
Q

principle goal of fertilisation

A

restore diploid

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18
Q

how could male infertility result

A

quantity or quality of sperm ejaculated

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19
Q

what is cleavage

A

repeated mitotic division of the zygote resulting in increased number of cells
daughter cells generated termed blastomeres
Zygote - morula

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20
Q

Bilaminar embryonic germ disc

A

epiblast and hypoblast(primitive endoderm) evolved from emrbyoblast

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21
Q

what is the embryonic germ disc

A

cluster of embryonic cells from blastocyst

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22
Q

where is the primitive streak found and what does it start

A

caudal end of epiblast
gastrulation
Defines all major body axes of the developing embryo - cranial - caudal axis , medial lateerla axis and left and right axis and dorsal and ventral axis is all established as a results of formation of primitive streak

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23
Q

what is gastrulation

A

process of epiblast cells movement through primitive streak transforming bilaminar germ disc into the trilaminar germ disc - then 3 primary germ layers
ectoderm ( epiblast )
mesoderm ( grey cells)
endoderm ( hypoblast)

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24
Q

when does gastrulation commence

A

15ht day with formation of primitive streak

25
Q

what is a congential malformation due to error of gastrulation

A

caudal dysplasia e.g. sirenomelia - legs fused together
dextrocardia - heart on right instead of left
situs inversus - major visceral organs are reversed or mirrored from their normal positions

26
Q

organogenesis

A

formation of the primary germ layers and major organs

27
Q

this layer gives rise to organs and structure that maintain contact with outside world
forms the neuroectoderm which forms the neural tube and neural crest cells and pituitary
sensory epithelium for the ear
epidermis of the skin
enamel of teeth
oral and anal canal epithelium
what layer?

A

derivatives of the ectodermal layer

28
Q

what 3 parts make up the mesoderm germ layer

A

paraxial
interrmediate
lateral plate

29
Q

what part of the mesoderm layer forms
somitomeres - in head called neuromeres
and then somites that are either side of the neural tube

A

paraxial

30
Q

can the age of the embryo be accurately determined by counting the somites at specific periodicity

A

yes

31
Q

what part of the mesoderm layer contributes to formation of structures of urogenital system inducing primordial germ cell gametes and gonads

A

intermediate mesoderm

32
Q

what part of the mesoderm layer splits into parietal and visceral

A

lateral plate mesoderm

33
Q

which part of the lateral plate mesoderm lines the cavity walls and forms dermis of skin in body wall and connective tissue and costal cartilage and pericardial membrane

A

parietal

34
Q

what part of the lateral plate mesoderm forms the gut wall with the endoderm and serous membranes surrounding organs and forms
BLOOD CELLS ADN BLOOD VESSELS

A

visceral

35
Q

what germ layer
is the main epithelial lining of the GI and pharynxc
respiratory tract, urinary bladder , urethra and tympanic membrane as well as auditory tube
parenchyma of thyroid and paraT liver and pancreas

A

endoderm germ layer

36
Q

what are the walls of the GIT formed from

A

smooth muscle and the connective tissue derived from mesoderm

37
Q

morphogenesis

A

form shaping process of the embryo - changes in cell shape size position number migration and adhesitivtiy

interference with diff tissuegrowth in E resuls in dysmorphogenisis and formation of birth defects

responses due to influence of genetic variation and environmental factros during devleometn - considered a normal

38
Q

those individuals who develop in close range of abstract norm both in form and function are said to have developed normally - what word describes this

A

normogenesis

39
Q

those individuals who develop outside the range are considered to develop abnormally - what word describes this

A

dysmorphogenesis

40
Q

what is a malformation

A

primary morphologic defects in an organ or body part e.g. neural tube due to close of neural folds
syndactly - failure of digits fully separated
caused by teratogens or genetic factors

41
Q

deformation

A

2nd morpjoligc defects imposed upon on organ or body part due to mechanical forces over a prolonged period of time
e.g. clubfeet - compression of amniotic cavity as a result of insufficient amniotic fluid

42
Q

what is a syndrome

A

when dysmorphognesis occurs as a pattern of well characterised multiple primary malformations in a predictable fashion in 1 or more due to a specific underlying angle or common cause

43
Q 
what problem causes these symptoms 
flat face 
small nose 
reduced muscle tone 
upwards slant to eyes 
enlarged tongue that stick out 
deep single palmar crease
hyper flexibility of joints
A

Downs syndrome

44
Q 
thin upper lip 
brain damage 
smooth philtrum 
short palpebral fissure length 
symtpks of what
A

fetal alcohol syndrome

45
Q

teratogen

A

factor or agent that causes a brith defect or congenital malformation

46
Q

factor that determine capacity of teratogen to produce BD

A

genotype concept and maternal genome
development stage at time of exposure
dose and duration of exposure

47
Q

pathogensis

A

abnormally development of a process

48
Q

when do errors of gastrulation occur

A

3rd week - epibalstic cells are sensitive

49
Q

a high dose of alcohol kills midline germ disc causing a deficiency of craniofacial structures what is this Called

A

holoprosencephaly - eyes close and cleft lip

50
Q

caudal dysplasia

A

mesodermal insufficiency which forms lower limns ad urogenital system and lumbosacral vertebrae

51
Q

situs inversus

A

transportation of viscera in thorax and abdomen

52
Q

sacrococcygeal teratomas

A

remnants of primitive streak persist in that region to form tumours

53
Q

in maternal serum screening wha protein is detected

A

alpha- feto protein - produced by the fatal liver - levels increase during pregnancy

need to be combined with more tests due to the fact that high false positive rate

54
Q

in a neural tube defect what is high that should be normal during gestation

A

maternal serum AFP

55
Q

in Down syndrome what hormones are high and low

A

HCG and INhbin A increased and estriol down

56
Q

nuchal translucency test

A

thickness of fluid at the neck - feotus with downs or other heart defects accumulate fluid in back of the neck during 1st trimester

57
Q

fetal echocardiogrpahy measure what

A

fetal HR and HB

58
Q

amniocentesis

A

analysis of amniotic fluid aspirated from the amniotic cavity 14 -16 weeks of gestation

59
Q

chronic villus sampling

A

analysts chronic tissue sample

Endocrine and Reproductive system (21 decks)

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