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FHMP > FHMP 027 CAL: the origins of body form and cell differentiation > Flashcards

FHMP 027 CAL: the origins of body form and cell differentiation Flashcards

1
Q

In humans how many chromosomes are found in the second polar body from oogenesis?

A
  • 23
  • haploid
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2
Q

what is a Graafian follicle?

A
  • a mature ovarian follicle composed of somatic cells surrounding a single oocyte
  • also known as tertiary, preovulatory and antral follicles
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3
Q

what are granulosa cells of the ovary and what do they form during pregancy?

A
  • cells in your ovary which produce oestrogen progesterone
  • they form the corpus luteum (luteal body)
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4
Q

what do granulosa cells become if there is no implantation?

A
  • corpus albicans (white body)
  • a connective tissue scar on the ovary that stays for a few months after the corpus leuteum degenerates
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5
Q

how long after ovulation is the human egg capable of being fertilised?

A
  • 24 hours
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6
Q
  • how long can sperm remain active in the female reproductive tract
A
  • up to 5 days
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7
Q

what is a zygote?

A
  • once the sperm has fertilised an egg
  • earliest stages of embryogenesis
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8
Q

what prevents the fertilised egg from implanting in the fallopian tubes?

A
  • zona pellucida
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9
Q

how many cells are present when the embryo undergoes compaction?

A
  • 12-16 cells
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10
Q

what proportion of human blastocyts fail to implant causing a spontaneous abortion?

A
  • 1/3
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11
Q

what tissue layers are found in the bilaminar disc?

A
  • epiblast and hypoblast
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12
Q

what tissue layers are found in the trilaminar disc?

A
  • ectoderm, mesoderm, endoderm
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13
Q

what structure does the prechordal plate become?

A
  • buccopharyngeal membrane
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14
Q

what process gives rise to the first blood vessels to form in the embryo?

A
  • vasculogenesis
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15
Q

where do the first blood cells form in the embryo?

A
  • formed by the extraembryonic mesoderm lining the yolk sac
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16
Q

in the embryo, where do you find the vitelline blood vessels?

A
  • yolk sac
  • vitelline arteries branch from the dorsal aorta
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17
Q

what happens to change primary stem villi into secondary stem villi?

A
  • primary villi are composed only of trophoblast
  • mesoderm grows into the core forming secondary villi and branches of the umbilical artery and umbilical vein grows into the mesoderm to form tertiary villi
18
Q

what endodermal structure is formed by the head fold?

A
  • endoderm is initially a flat simple epithelium forming the embryonic surface of the yolk sac
  • it is turned into a tube by the process of ventral folding
  • first embryonic tissue pushes in from the rostral end to form the head fold and then the foregut
19
Q

what is the vitelline duct?

A
  • tube joining the midgut to the yolk sac formed during embryonic folding
20
Q

what are the first segmented structures to appear in the human embryo?

A
  • somites
  • during 4th week of development
21
Q

how many somites are present on the 28th day of development

A
  • 30-32 pairs
22
Q

why are somites useful in staging an embryo?

A
  • because they form at a steady rate and are clearly visible through thr surface of the embryo
23
Q

what is preformation?

A
  • in the 17th and 18th century people believed humans were fully formed already in the head of the sperm
24
Q

what is epigenesis?

A
  • where tissues and organs form gradually and the complexity of the embryo increases with time
25
Q

what does totipotent mean?

A
  • forms all embryonic and extraembryonic cell types
26
Q

what does pluripotent mean?

A
  • forms all embryonic cell types
27
Q

what does multipotent mean?

A
  • forms multiple cell types
28
Q

what does tri or bi potent mean?

A
  • form 3 or 2 different cell types
29
Q

what does unipotent mean?

A
  • forms only 1 cell type
30
Q

what are the 3 states of cell commitment?

A
  • specification
  • determination
  • differentiation
31
Q

what is specification?

A
  • cells receive instructions on what they are to become but they do not become fully committed
  • their fate can be changed if move to a new environment
32
Q

what is determination?

A
  • cells become committed to their cell type fate
  • cannot be changed
33
Q

what is differentiation?

A
  • cells acquire those characteristics that distinguish them for their cell type
34
Q

what are the 3 mechanisms of cell commitment?

A
  • localised determinants
  • embryonic induction
  • morphogen gradients
35
Q

what is localised determinants?

A
  • in the 1800s it was suggested that cell fates may be specified by localised determinants, laid down in the cytoplasm of the egg during oogenesis
  • each major cell type has its own determinant
  • so only cells with a muscle determinant will become muscle
  • however, this was found not to be true using sea urchin embryos which showed if you split the embryo early, all larvae will grow normally and contain all cell types
  • called regulative development
36
Q

what is embryonic induction?

A
  • the process whereby a cell’s fate is changed by signals from an adjacent group of cells
  • it requires 2 types of cells: a signaling cell and a responding cell
  • competence = the ability of a cell to respond to a signal
37
Q

what are morphogen gradients?

A
  • a mechanism by which the emission of a signal from one part of an embryo can determine the location, differentiation and fate of many surrounding cells
  • e.g. hedgehog genes
38
Q

what are induced pluripotent cells?

A
  • adult cells that are reprogrammed to take on a different cell types
39
Q

what are epigenetic control mechanisms?

A
  • gene transcription is regulated through epigenetic mechanism which affect chromatic structure , including modifications of both DNA and associated core histones, methylation of DNA in gene promoters is associated with gene silencing while methylation of core histones is associated with both gene activation and silencing
40
Q

whats the difference between transcribe genes and non-transcribed genes?

A
  • transcribed genes = contain histone modifications that create loose chromatin that is accessible to transcription factors
    -non-transcribed genes = may have highly methylated DNA and alternative histone modification to create compact chromatin which in inaccessible to transcription factors

FHMP (18 decks)

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