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psio 120 > developement and ageing > Flashcards

developement and ageing Flashcards

1
Q

Fertilisation

A

the union of haploid genetic material to form a single diploid nucleus

  • peristaltic contraction and wave-like motion of cilia transport the oocyte down the uterine tube towards the uterus.
  • sperm swim up the female reproductive tract into the uterine tube by the flagella tails
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2
Q

capacitation of sperm

A

the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg.

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3
Q

capacitation of ejaculated sperm

A
  • leak from the vagina
  • destroyed by the acidity
  • fail to pass through the cervix
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4
Q

why does sperm require capacitation in the oviduct?

A
  • normally inactive
  • lower membrane fluidity via loss of cholesterol
  • protein and carbohydratesremovals = allows interaction with ovum membrane
    -altered membrane potential - allows ca2+ entry for acrosomal entry
    -
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5
Q

how does sperm migrate through the reproductive tract

A

chemotaxis

can only pass through cervical mucous at late follicular stage

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6
Q

For fertilisation to occur?

A
  • sperm must penetrate approaching oocyte
  • penetrate corona radiata
  • cross zona pellucida
  • cross oocyte membrane
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7
Q

Acrosomal reaction

A

release of digestive enzymes = allows sperm to cross zp and for sperms nucleus to enter oocyte.

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8
Q

cortisol reaction

A

prevents polyspermy = rapid activation of cortical granules to release hydrolytic enzymes, preventing further sperm entry

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9
Q

zygote

A
  • from fertilisation to the end of the second week
  • cell division creates a blastocyst that migrates along the oviduct to the uterus
  • implantation
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10
Q

embryo

A
  • weeks 3-8
  • all principal adults organs, body cavities, limbs and facial development begins
  • period of organogenesis (formation of organs)
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11
Q

foetus

A
  • weeks 9 to birth
  • placenta becomes fully functional
  • major period of growth
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12
Q

formation of zygote

A
  • sperm must penetrate the outer layers of the oocyte
  • when sperm bind to zona pellucida acrosome contents are released (acrosomal reaction)
  • sperm fuses with secondary oocyte
    cortical reaction - granules release chemicals to change ZP preventing other sperm from entering
    oocyte complexes meiosis (expulsion of polar body).
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13
Q

events of fertilisation

A
  1. oocyte at ovulation
  2. fertilisation and oocyte activation
  3. pronucleus formation begins
  4. spindle formation and cleavage preparation
  5. amphimixis occurs and cleavage begins
  6. cytokenesis begins
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14
Q

early rapid mitotic cell division of a zygote

A

cleavage

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15
Q

morula

A

successive cleavages produce solid mass of cells
- as the number of morula increases, it moves from the site of fertilisation down the uterine tube towards the uterus and enters the uterine cavity.

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16
Q

Blastocyst

A

morula develops into a blastocyst

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17
Q

At the end of the zygote

A
  • embryonic disc has formed
  • yolk sac and chorion are seen
  • implantation is complete
  • lacunae have started forming in the endometrium
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18
Q

Embyro

A
  • weeks 3-8
  • major period of organeogenesis
  • sexual differentiation initiated
  • placenta fully developed
  • cell proliferation, differentiation, migration and programmed cell death
19
Q

What happens at a week 3?

A
  • allontois begins to forms (from yolk sac, grows towards all of blastocyst)
  • chrorion formation
    mesoderm surrounds blastocyst
  • starts too see cellular differentiation
  • gastrulation occurs (folding of embyronic cells)
20
Q

ectoderm

A

bran, spinal chord, hair, nails

21
Q

mesoderm

A

intermediate layer

22
Q

endoderm

A

epithelial lining

23
Q

What is the allantois

A

extends into umbilical stalk and forms part of urinary bladder

24
Q

Amnion

A
  • thin membrane which surrounds the embyro
  • fills with fluid - filtrate of maternal of maternal blood and foetal urine
  • shock development, temperature regulation, prevents adhesions
25
Q

yolk sac

A
  • transfer nutrients to the embryo - needed before the placenta and the umbilical cord have formed.
  • site of early blood protection
  • develops into gonadal stem cells which migrate into embryo
26
Q

Chorion

A
  • develops into placenta
  • secretes hcg
  • will develop to contain blood vessels
  • blood vessels anastomose with umical cord vessels
27
Q

Allontois

A
  • participates in gas exchange and waste removal early in pregnancy
28
Q

How does embryo sexual differentiates?

A
  • all embryos starts female
  • initially have Mullerian ducts and wolferian ducts
  • At 10 weeks (females) wolfian ducts degenerates (begins oogenesis)
  • At week 8 in males - sky gene activates.
    The release of anti-mullerian hormone initiates degeneration of Mullerian ducts.
    Release of DHT = development of male reproductive structures
29
Q

Foetus stage

A
  • week 9 to birth
  • major period of growth
  • teratogens harms the development
30
Q

change in chorion in hormone

A
  • from day 8 until 4 months secretes hcg
  • hcg maintains corpus luteum
  • corpus luteum produces progesterone and oestrogen, preventing menstruation and ovulation
  • progesterone suppresses myometrium contractions
31
Q

change in hormone production in the placenta?

A
  • by 4 months produces progesterone and oestrogen, corpus luteum is no longer necessary
  • becomes a major endocrine organ
32
Q

maternal changes during pregnancy?

A
  • weight gain
  • increase heart rate
  • increase blood volume
  • increase cardiac output
  • increased ventilation
  • GI tract compressed causing heartburn and constipation
33
Q

Paturition (labour)

A

Labour begins when progesterone’s inhibition is overcome by an increase in oestrogen levels

  • progesterone inhibits uterine interaction
  • progesterone secretion plateaus
  • late in pregnancy = placenta produces large amounts of oestrogen
  • oestrogen overcome progesterone and labour begins
34
Q

positive feedback during labour

A
  • uterine contractions force the foetal head into cervix
  • stretch receptors send nerve impulses to the hypothalamus causing the release of oxytocin
  • oxytocin = more contractions producing more stretch of cervix
35
Q

stages of birth

A
  1. Dilation
  2. Expulsion
  3. Placental stage
36
Q

post-partum period

A

the period following delivery of the baby and the placenta

  • reproductive organs return to normal state
  • uterus decreases in size
  • uterine discharge of blood for 2-4 weeks
37
Q

Milk let down reflex

A

milk production stimulated by prolactin, release in response to oxytocin and inhibition of production by progesterone.

38
Q

role of oxytocin

A

causes release of milk into mammary glands

39
Q

stages of life

A
  • neonatal
  • infancy
  • childhood
  • adolescence
  • adulthood
  • senescence
40
Q

senescence

A

decline in function in most systems

41
Q

menopause

A

loss of menstrual cycle - exhausted follicle supply and loss of oestrogen production

42
Q

andropause

A

reduced testestrone

43
Q

programed ageing

A

cell has a limited amount of divisions.

  • telomeres shorten to prevent chromosomal damage
  • once telomeres are ‘used’ genetic material is degraded
  • telomeres repairs telomeres in young
44
Q

non-programmed ageing

A
  • cells and DNA are damaged overtime

due to cells divisions and environmental factors e.g. UV damage

psio 120 (9 decks)

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