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1 SUGER > reproduction > Flashcards

reproduction Flashcards

1
Q

what gene on the Y chromosome determines the male sex?

A

SRY gene - means testes develop

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2
Q

what are the 3 stages of gametogenesis?

A
  1. mitosis
  2. meiosis 1
  3. meiosis 2
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3
Q

what happens in the mitosis stage of gametogenesis?

A

proliferation of the primordial germ cells

each mitotic division produces 2 genetically identical daughter cells

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4
Q

what happens just before meioses 1?

A

interphase

- homologous chromosome pairs are duplicated

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5
Q

what happens in the meiosis 1 stage of gametogenesis?

A
  • separates the homologous chromosome pairs in the diploid

- producing 2 haploids

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6
Q

what happens in the meiosis 2 stage of gametogenesis?

A
  • Sister chromatids separated

- produces 4 haploids

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7
Q

how in genetic variation introduced into gametes?

A
  • cross over in prophase 1

- independent assortment

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8
Q

where does spermatogenesis happen?

A

testes (seminiferous tubules)

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9
Q

what is the name of the germ cell that undergoes spermatogenesis?

and oogenesis?

A

spermatogonium (a spermatogonia)

oogonia ( an oogonium)

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10
Q

what does mitosis of a spermatogonia/oogonia produce?

A

a primary spermatocyte

a primary oocyte

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11
Q

what does meiosis 1 of a primary spermatocyte/oocyte produce?

A

secondary spermatocytes/oocytes

2 haploids

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12
Q

what does meiosis 2 of a secondary spermatocyte produce?

A

4 spermatids, these then differentiate into sperm

fertilised oocyte

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13
Q

what is the blood testses barrier?

A

Sertoli cells forming a ring around circumference of tubule stopping movement into lumen

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14
Q

what is the purpose of the blood testes barrier?

A
  • retains luminal fluid

- proper conditions for germ cell development

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15
Q

what are the 2 compartments of the blood testes barrier?

A

basal (BM to tight junctions of Sertoli cells)

central (tight junctions to lumen)

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16
Q

what stage of spermatogenesis happens in the basal compartment?

A

differentiate into primary spermatocytes

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17
Q

what stage of spermatogenesis happens in the central compartment?

A

meiosis 1 and 2

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18
Q

what gonadotrophin stimulates Sertoli cells?

A

FSH

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19
Q

what gonadotrophin stimulates Leydig cells?

A

LH

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20
Q

what do sertoli cells do in the HPG axis?

A

FSH stimulates Sertoli cells to release inhibit and initiate spermatogenesis

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21
Q

what do Leydig cells do in the HPG axis?

A

LH stimulates Leydig cells to secrete testosterone.

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22
Q

what are the local and general affects of testosterone (HPG axis)

A

local : diffuses into Sertoli cells and stimulates spermatogenesis

general: reproductive tract

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23
Q

what hormones of the HPG axis increase during puberty?

A

GnRH,GHRH, FSH, LH,GH

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24
Q

physical changes for males in puberty

A
  • 9-14
  • testicular enlargement
  • facial hair growth
  • spermatogenesis begins
  • growth spurt
  • body odour
  • mood changes
  • acne
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25
Q

physical changes for females in puberty

A
  • 8-14
  • menarche (2.5 yrs into puberty)
  • growth spurt
  • hair growth (pubic an axillary)
  • breast enlargement
  • body odour and mood changes
  • acne
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26
Q

what is menopause? when does it happen?

A

The cessation of menstruation, when the ovaries STOP releasing eggs because of a reduction in circulating oestrogen

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27
Q

when does menopause happen?

A

usually occurring between 48-52 years,

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28
Q

give 3 short term signs of menopause?

A

hot flushes
shorter menstruation cycle
skin dryness

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29
Q

give 3 long term symptoms of menopause?

A

vagina dryness
hair loss
general aches and pains

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30
Q

what can menopause put women more at risk of developing ?

A

Osteoporosis

oestrogen is essential for bone density

drops

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31
Q

menstrual cycle can be split into 2 phases of equal length, seperated by ovulation:

A

follicular - development of mature follicle and secondary oocyte

luteal - post ovulation and death of corpus callosum

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32
Q

what does FSH do in the female HPG axis? (4)

A
  • binds ot granulosa cells
    -stimulates follicle growth
    -permit the conversion of androgens (from theca cells) to oestrogens
    stimulate inhibin secretion
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33
Q

what does LH do in the female HPG axis?

A

acts on theca cells

stimulates production and secretion of androgens

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34
Q

how does moderate oestrogen levels affect HPG axis?

A

negative feedback

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35
Q

how does high oestrogen levels affect HPG axis?

A

positive effect

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36
Q

how does progesterone + oestrogen present affect HPG axis?

A

negative feedback

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37
Q

what does inhibin do?

A

secreted by granulosa cells

selectively inhibits ant.pituitiary release of FSH

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38
Q

how many follicles mature during the follicular phase of menstrual cycle (day 1-13)?

A

only 1 dominant follicle reaches maturity

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39
Q

what is the impact of the LH surge on granulosa cells?

A
  • increases inhibin so stops FSH production

- Granulosa cells become luteinised and express receptors for LH.

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40
Q

when does ovulation happen in menstrual cycle?

A

day 14

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41
Q

what triggers ovulation?

A

LH surge causes dominant follicle to rupture and release mature oocyte

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42
Q

what does it mean if cells have been luteinised?

A

proliferation ceases, terminal differentiation, produces high levels of progesterone

eg. follicle post rupture

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43
Q

how is the cycle stalled after ovulation?

A
  • the follicle remains luteinised after the LH surge
  • therefore it is now secreting oestrogen + progesterone
  • this causes negative feedback on the HPG axis.
  • cycle is stalled in anticipation of fertilisation
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44
Q

what is the corpus luteum?

A

tissue of the collapsed mature follicle after ovulation

becomes glandular and secretes oestrogen, progesterone and inhibin

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45
Q

what happens in the luteal phase of menstrual cycle?

A

day 14-28

  • corpus luteum secretes steroids to create conditions for fertilisation
  • if no fertilisation by day 28, it regresses
  • hormones fall and HPG resets
  • menstruation occurs
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46
Q

what happens to the corpus leteum if fertilisation occurs?

A
  • it doesn’t regress, its maintained
  • due to placental HcG
  • it produces progesterone and oestrogen for first 2 months of pregnancy
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47
Q

what are the 2 layers of the uterus?

A

myometrium - smooth muscle, external

endometrium - internal

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48
Q

3 layers of the endometrium:

A
  1. stratum compactum
  2. stratum spongiosum
  3. stratum basalis
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49
Q

what are the 3 phases of the uterine cycle?

A
  1. menses
  2. proliferative
  3. secretory
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50
Q

what happens in menses?

A
  • the endometrium degenerates
  • corpus luteum brakes down
  • there’s menstrual flow when the spinal arteries rupture
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51
Q

what happens in proliferative phase of uterine cycle?

A

alongside follicular phase

OESTROGEN:

  • endometrium thickens
  • increased growth and mobility of myometrium
  • thin alkaline cervical mucous
  • renews glandular structures
  • initiates fallopian tibe formation
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52
Q

what happens in secretory phase of uterine cycle?

A

alongside the luteal phase

PROGESTRONE

  • endometrium thickens to glandular form
  • reduction of mobility of myometrium
  • thick acidic cervical mucous
  • increases spiral arteries
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53
Q

how is the egg transported to site of fertilisation?

A
  1. after ovulation, emerges on surface of ovary
  2. fimbriae move towards it
  3. fimbrae cilia sweep egg into fallopian tube
  4. fallopian cilia beat it close to uterus
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54
Q

in what window must fertilisation happen?

A

5 days before to 1 day after ovulation’

55
Q

what factors help the transport of sperm from vagina (during intercourse) to Fallopian tube

A
  • flagella + ejaculate pressure propels sperm through external OS of Cervix
  • mitochondria supply energy needed for long trip
  • cervical muscus is watery
56
Q

what final adaptions do the sperm undertake when in the Fallopian tubes? what is this process called?

A

capacitation

  • stronger tail
  • develops acrosomal enzymes in membrane which allows it to fuse with egg
57
Q

where does fusion of the egg and sperm commonly take place?

A

in the ampulla of the Fallopian tube

58
Q

how does sperm fertilise the egg?

A
  1. binds to glycoprotein receptors on the zona pellucida surface
  2. acrosomal enzymes digest a path through to egg plasma membrane
  3. sperm head bases into cytosol of egg
59
Q

what is a fertilised egg called? with 23 pairs of chromosomes?>

60
Q

how does the egg prevent polyspermy?

A
  • egg membrane potential changes after one sperm has fused with it
  • releases enzymes that inactivate sperm receptors on zona pellucida (cortical reaction)
61
Q

what process occurs 4-7 hours post fusion?

A

meiosis 2 resumes

  • forms a polar body which. degernates
  • and a fertilised zygote with 23 chromosomes from egg, 23 from sperm
62
Q

day 2-3 post fertilisation : what happens during CLEAVAGE?

A
  • zygote remains in Fallopian tubes
  • due to smooth muscle contractions stimulated by oestrogen at the junctions between tube and uterus
  • cell divisions occur (not cell growth) to increase numbers
  • these cells are totipotent
63
Q

what does totipotent mean?

A

stem cells that could develop into an entire individual

64
Q

day 4 post fertilisation : what happens during COMPACTION?

A

cells flatten and tight junctions form

65
Q

day 5 post fertilisation : what happens during COMPACTION?

A

fertilised egg is now a rapidly dividing ball of cells known as a BLASTOCYST
- cells begin to differentiate

66
Q

what are the layers of the blastocysts?

A
  • central fluid filled cavity
  • inner cell mass
  • the trophoblasts ( outer cell layer)
67
Q

day 6 post fertilisation : what happens during EXPANSION?

A
  • diameter of blastocyst increases because cavity expands

- the zona pellucida layer thins

68
Q

day 6+ post fertilisation : what happens during HATCHING?

A

embryo hatches from the zona pellucida

69
Q

when does implantation of the blastocyst happen>

A

21st day of cycle

70
Q

what happens during APPOSITION implantation stage?

A

hatched blastocyst orientates and synchs with endometrium

71
Q

what happens during ATTACHEMENT implantation stage?

A
  • endometrial epithelial cells & trophoblastic cells attach

- via links called Integrins

72
Q

what happens during DIFFERENTIATION implantation stage?

A

trophoblast (outer part of blastocyst) develops 2 layers

  • cytotrophoblast (inner)
  • syncytiotrophoblast (outer)
73
Q

what is the significance of the syncytiotrophoblast layer of the trophoblast?

A

will be involved with placenta, has proteolytic enzymes

74
Q

what happens during INVASION implantation stage?

A

enzymatic degradation of the basal lamina

75
Q

what happens during DECIDUAL implantation stage?

A

stroma cells adjacent to blatstocyst differentiate

76
Q

what happens during MATERNAL RECOGNITION implantation stage?

A
  • secretion of interleukin-2

- prevents antigenic rejection of embryo

77
Q

how does the early embryo (just after implantation) get metabolic fuel and raw materials?

A

provided by endometrial epithelial cells

78
Q

what structure supplies metabolic fuel and raw materials to the embryo AFTER a few weeks?

79
Q

from what does the placenta develop?

A

from the outer cell layer of the primary trophoblastic cell mass (TCM)

= the chorion

TCM invades endometrium
via chorion villi projecting

80
Q

what are the placental sinuses?

A

pools of maternal blood that surround the villus of the chorion

81
Q

what does the umbilical vein transport?

A

oxygenated blood from mother

into placenta and liver of foetus

82
Q

what do the 2 umbilical arteries transport?

A

deoxygenated blood from foetus to placenta and back to mother via umbilical cord

83
Q

how is blood transported from the liver to the heart of the foetus?

A

the ductus venous shunts blood from umbilical vein at level of liver, into the IVC, which carries the oxygenated blood to heart

84
Q

what blood does the fetal IVC pass into the heart?

oxygenated/deoxygenated?

A

mixed

partially oxygenated (from mother) 
partially deoxygenated (from fetal circulation)
85
Q

what are the 3 routes blood can take in the fetal heart, from the RA?

A
  1. normal,
    RA → RV→ pulmonary artery→ lungs → …
  2. bypass lungs,
    RA → RV → pulmonary artery → through the ductus arteriosus → aorta
  3. bypass lungs
    RA → through patent foramen Ovale → LA → LV → aorta
86
Q

do fetal and maternal blood ever mix?

87
Q

what is the maternal part of the placenta called?

A

the decidua

  • uterine lining that forms maternal part of placenta,
  • it underlies the chorion
88
Q

give 2 examples of how the placenta has a metabolic role ?

A
  • it provides nutrients and energy

- it synthesises glycogen, cholesterol, fatty acids

89
Q

give 7 examples of what the placenta transports?

A
  • O2 and CO2
  • water
  • amino acids
  • maternal antibodies
  • waster products eg. urea
  • drugs
  • steroid hormones
90
Q

at what stage after implantation is the placenta fully established?

A
  • 5 weeks after
    • fetal heart is pumping blood
    • nutrient and waste mechanism is functioning
91
Q

what is the amniotic cavity?

A
  • space between inner cell mass (embryo) and outer layer of trophoblast cells (chorion)
  • forms as placenta develops
  • foetus floats in it
92
Q

what is the amnion?

A

ie. amniotic sac

= epithelial layer lining the amntioic cavity

  • fuses with chorion to form 1 combined membrane surrounds the foetus

contains amniotic fluid

93
Q

what is the role of amniotic fluid?

A

buffers mechanical disturbances and temperature variances

94
Q

what structure produces almost all of the oestrogen and progesterone for the first 2 months of pregnancy?

A

the corpus luteum

95
Q

which hormones gradually increase throughout pregnancy?

A

oestrogen and progesterone plasma concentrations

96
Q

what is the effect of oestrogen during pregnancy? (4)

A
  • stimulates uterine muscles to grow
  • regulates progesterone
  • prepares breasts for feeding
  • synthesis oxycontin receptors
97
Q

what is the effect of progesterone during pregnancy? (2)

A
  • inhibits uterine contractility - so foetus isn’t expelled prematurely
  • increases thickness of uterine lining - to prevent miscarriage
98
Q

what is hCG and what cells produce it?

A

human chorionic gonadotropin

produced by implanted trophoblast cells

99
Q

what are the roles of hCG?

A
  • pregnancy test
  • prevents degeneration of corpus luteum
  • stimulates it to produce o+p
100
Q

when is hCG secretion at its peak ?

A

80 days after last mentsruation

101
Q

when is hCG secretion at its lowest?

A

after peak (day 80) it decreases and is at lowest by end of 3rd month of pregnancy

102
Q

what happens once hCG is at A very low concentration (end of 3 months)

A
  • corpus luteum degenerates

- trophoblast cells of the placenta take over role of secreting oestrogen and progesterone

103
Q

how does the placenta (trophoblast cells) synthesise progesterone?

A
  • contains specific enzymes that do so
104
Q

how does the placenta (trophoblast cells) synthesise oestrogen?

A
  • maternal ovaries + adrenal medulla + fetal adnreal medulla
  • supply cells with androgens (precursors)
105
Q

why are their no menstrual cycles during pregnancy?

A
  • high concentrations of progesterone + oestrogen secreted by corpus luteum, and then placenta
  • mean constantly low levels of gonadotropins (LH and FSH)
106
Q

where is prolactin produced?

A

anterior pituitary gland

107
Q

what is the role of prolactin?

A
  • prevents ovulation

- helps milk production

108
Q

when are prolactin levels high?

A

end of pregnancy

109
Q

where is Relaxin produced?

A

ovary + placenta

highest in early pregnancy

110
Q

what is the role of Relaxin?

A

limits uterine activity

softens cervix - cervial ripening

111
Q

where is oxycontin produced?

A

posterior pituitary

112
Q

what is the role of oxycontin?

A
  • stimulates uterine contractions during labour
  • triggers caring reproductive behaviours
  • its used as a dug to induce labour
113
Q

what are prostaglandins?

A

hormones produced by uterine tissues to initiate labour

eg. PGF2a

enhances actions of oxytocin

114
Q

physiological changes during pregnancy: adrenal cortex

A

increase secretion of aldosterone and cortisol

115
Q

physiological changes during pregnancy: kidneys

A 
increased secretion of: 
- renin
erythropoietin 
- 1,25-dihydroxyvitamin D
-retention of water and salt
116
Q

physiological changes during pregnancy: posterior pituitary gland

A

increased section of Vasopressin/antidiuretic hormone (ADH)

117
Q

physiological changes during pregnancy: blood volume

118
Q

physiological changes during pregnancy: bone turnover

A

increased because more PTH and vitamin D

119
Q

physiological changes during pregnancy: respiration

A

hyperventilation occurs due to increased progesterone

increased alveolar ventilation

120
Q

physiological changes during pregnancy: GI

A

increased acid reflux and gastroparesis (delayed emptying)

121
Q

physiological changes during pregnancy: skin

A
  • linea nigra (dark central abdominal line)
  • striae gravidarum (stretch marks in lumbar/lower abdomen regions)
  • darkened areolar on breasts
122
Q

what is parturition

A

‘birth process’ = last few weeks of pregnancy + delivery (intra-uterine to extra-uterine life)

123
Q

changes to smooth muscle during parturition :

A

rising oestrogen stimulates smooth muscle cells to synthesise CONNEXINS

these proteins form gap junctions

helps to coordinate contractions

124
Q

what is the term for the growth and remodelling of cervix prior to labour?

making the cervix soft and flexible

A

cervical ripening

125
Q

when does cervical ripening happen? what hormone stimulates it?

A

last 3 months of pregnancy, due to rising oestrogen and decreasing progesterone

126
Q

what hormones mediate the actions of the enzymes that break down the collagen fibres of the cervix to make it softer/flexible during cervial ripening?

A

enzymes actions mediated by oestrogen, placental prostaglandins and relaxin

127
Q

what initiates labour?

A

increased PGFa → increased oxytocin

+ pressure on cervix

128
Q

what are the 3 main steps of labour?

A
  1. amniotic sac raptures
  2. uterine contractions
  3. cervix dilation (widest = 10sm)
129
Q

what are the 3 actual phases of labour?

A
  1. latent pahse
  2. actions phase
  3. post partum phase
130
Q

what happens in the latent phase of labour?

A

8 hours of minor cervical dilation

131
Q

what happens in the action phase of labour?

A
  • organised uterine contractions and cervical dilations
  • full dilation results in foetal expulsion
  • then placental expulsion
132
Q

what happens in the post partum phase of labour?

A

extra-uterine life

133
Q

how do contraceptives work?/

A

contain oestrogen and progesterone

these hormones inhibit anterior pituitary gland from releasing LH and FSH (gonadotrpoins)

therefore ovulation cannot happen

1 SUGER (9 decks)

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