endocrine control of the reproductive system Flashcards

1
Q

what are the 2 main structures responsible for hormonal regulation

A
  • hypothalamus
  • anterior pituitary gland
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2
Q

what is the function of the hypothalamus

A
  • controls pituitary hormone release
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3
Q

what 2 hormones released by the hypothalamus are related to reproduction

A
  • gondaotropin releasing hormone (GnRH)
  • prolactin inhibiting hormone (PIH/Dopamine)
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4
Q

what are the 3 main functions of the pituitary gland in terms of reproduction

A
  1. stimulates production of oestrogen, progesterone in females
  2. controls ovulation and pregnancy
  3. controls testosterone production and spermatogenesis
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5
Q

what are 3 hormones released by the pituitary gland

A
  • follicle stimulating hormone (FSH)
  • Luteinizing hormone (LH)
  • Prolactin (PRL)
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6
Q

describe the process of the hypothalamic pituitary axis

A
  • hypothalamus secretes GnRH
  • this stimulates the anterior pituitary gland to release LH/FSH
  • this then effects the gonads causing the testis to produce testosterone and the ovaries to produce oestrogen and progestogen
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7
Q

what is Kisspeptin

A

a group of hypothalamic peptides that are essential for normal human fertility

e.g Kisspeptin —> GnRH —> LH/FSH —–> Gonads

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8
Q

describe how female puberty starts

A
  • begins with gradual increase in pulsatile GnRH secretion by hypothalamus
  • release of LH/FSH (Kisspeptin)
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9
Q

at what age range does female puberty begin

A

11-16

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10
Q

the first few cycles of female puberty are anovulatory, what does this mean

A
  • not ovulating/releasing an egg
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11
Q

what is thelarche

A

beginning of breast development

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12
Q

describe starting of puberty in boys

A

from ages of 13, increased production of GnRH

  • causing testosterone level changes
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13
Q

what is spermatogonia

A

undifferentiated male germ cell

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14
Q

what happens to spermatogonia at puberty

A

undergoes mitosis

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15
Q

what does it mean when a mammalian embryo, the gonad is bipotential

A

can from ovary or testis

  • the undifferentiated gonand consists of precursor cell types that can follow either the female or male pathway
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16
Q

what are the 4 phases of the menstural cycle

A
  1. menstural phase
  2. follicular phase
  3. ovulation phase
  4. luteal phase
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17
Q

what are the 3 phases of the ovarian cycle

A
  1. follicular phase
  2. ovulation
    3, luteal phase
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18
Q

what happens during each phase of the ovarian cycle

A

follicular phase= follicule grows

ovulation - follicle released

luteal phase - corpus luteum forms then degenerates

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19
Q

at what stage of the ovarial cycle is FSH/LH levels hgihest

A

Just prior to ovulation (day 14)

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20
Q

at what stage of the ovarian cycle is progesterone levels highest

A

luteal phase (around 21 days)

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21
Q

what arteries supply the vaginal, uterus and ovaries

A

vagina = vaginal artery

uterus = uterine artery

ovary = ovarian artery

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22
Q

egg does not become fertilized, the lining of the uterus (endometrium) is shed during menstruation, describe the variation in thickness of endometrium over the menstural cycle

A
  • menstural phase / follicular phase = very thin endometrium
  • proliferative phase / ovulation = growing endometrium
  • secretory pro gestational phase / luteal phase = endometrium thickness at a maximum
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23
Q

what is the function of FSH

A

triggers the growth of eggs in the ovaries and gets the eggs ready for ovulation.

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24
Q

what is function of LH

A

LH stimulates steroid release from the ovaries, ovulation, and the release of progesterone after ovulation by the corpus luteum

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25
Q

what is the function of progesterone and where’s it made/released

A

to prepare the endometrium (lining of your uterus) for a fertilized egg to implant and grow

  • corpus luteum in ovary
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26
Q

what is function of oestrogen and where is it made

A

produced in your ovaries and helps your body develop pubic hair, breasts, and a regular menstrual cycle (periods).

-stimulate growth of organs important for reproduction
- stim bone growth
- increase body metabolic rate
- increase fat deposition in subcutaneous tissue
- softening and better vascularisation of skin etc

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27
Q

describe why during the ovulation phase there is LH/FSH surge and decline in oestrogen

A
  • after follicle phase/ follicle growth, collagenase (enzyme) digests the follicle wall
  • the follicle ruptures = ovulation (egg released)
  • as a result, oestrogen levels drop to prevent further ovulation (only one egg at a time)
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28
Q

what happens during the luteal phase

A
  • ruptured follicle transforms to corpus luteum through luteinization
  • yellow comes from cholesterol (precursor of steroid hormones)
  • corpus luteum secretes progesterone, which is dominant hormone of 2nd half of cycle
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29
Q

what is the process called of follicle turning into corpus luteum

A

lutenization

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30
Q

what is the 2 roles of progesterone

A
  1. inhibits FSH and LH so no further follicle development in ovulation and current cycle
  2. prepares uterus for pregnancy should fertilisation occur
31
Q

what happens to the corpus luteum is theres no fertilization also known as menstural phase

A

(menstural phase)

  1. CL degenerates randomly
  2. progesterone levels fall
  3. uterus loses endocrine support
  4. mensturation
  5. FSH and LH work on follicles again
32
Q

what is the role of the corpus luteum if there is fertilization

A
  • maintains uterine lining until placenta takes over as a main producer of progesterone at 3 months
33
Q

what maintains the corpus luteum during fertilisation

A

hCG from chorium

34
Q

endometrial cycle =

  • proliferative phase
  • secretory phase
  • menstural phase

what happens at each of there

A

poliferative phase = oestrogen goes down, growth of endometrium etc

secretory phase = rise in progesterone, growth of endometrium, softens connective tissue in prep for implantation

menstural phase = CL degeneration, progesterone and oestrogen drops, bleeding etc

35
Q

what are 3 ways oral contraceptives work

A
  1. utilise natural hormonal cycle to prevent ovulation
  2. altering mucus in cervix to prevent sperm movement
  3. changing endometrium so implantation is impossible
36
Q

how can progesterone work as contraceptive

A

progesterone prevents FSH but promotes coined production of thick vervical movement and inhibits endometrial development

37
Q

how can oestrogen work as contraceptive

A

prevent ovum maturation by inhibiting LH surge

38
Q

negatives of oral contraceptives

A
  • x3 increase in thromboembolism
  • cardiovascular disease in smoking women
  • increase susceptibility to certain cancer e. breast
39
Q

pros of oral contracepts

A
  • reduce indigents of endometrial and ovarian cancers
  • decrease risk of ectopic pregnancy
  • reduced heaviness of menstural bleeding
40
Q

what age would menopause hit

A

40-50

41
Q

what causes menopasue

A

no more follicle supply

42
Q

how are hormones affected during menopause

A
  • decreased production of oestrogen
  • FSH production increases
43
Q

what happens as a result of lack of oestrogen during menopause

A

physiological changes e.g hot flushes, irritability, fatigue, anxiety

44
Q

what are the sertoli and leydig cells in the male reproductive system

A
  • Sertoli cells are normally located in the male reproductive glands (the testes). They feed sperm cells.
  • The Leydig cells, also located in the testes, release testosterone
45
Q

describe the hormonal control of male reproductive system

A
  • hypothalamus releases GnRH
  • this stimulates the anterior pituitary gland to release FSH/LH
  • FSH triggers Sertoli cells to under go spermatogenesis
  • LH triggers leydig cells to release testosterone
46
Q

how does growth hormone affect males

A

controls metabolic function of testis

47
Q

how does luteinising hormone affect males

A

stimulates leydig cells to produce testosterone

48
Q

how does follicle stimulating hormone affect males

A

stimulates Sertoli cells to help with transition of spermatids to stem (spermatogenesis)

48
Q

how does testosterone affect males

A

secreted by leydig cells, growth and division of germinal cells

49
Q

what is testosterone responsible for

A

male foetus development
descent of testes
adult male primary and secondary body characteristics

50
Q

how does oestrogen affect males

A

formed from testosterone by Sertoli cells after FSH stimulation

51
Q

what 2 other androgens are secreted by interstitial cells of leydig besides testosterone

A
  • dihydrotestosterone (DHT)
  • androstenedione
52
Q

where does testosterone that isnt converted to androstenedione or DHT gone

A

excreted in liver bile or urine

53
Q

note there are numerous leydig cells in new born males, none in childhood, then numerous after pubety

also when tumours develop, large amount of testosterone is secreted

A
54
Q

what event does the parasympathetic and sympathetic pathway cause in the penis

A

parasympathetic = erection

sympathetic = ejaculation

55
Q

what are the components of seminal vesicle fluid

A
  • fructose
  • citric acid
  • prostaglandins
  • fibrinogen
56
Q

what are the components of prostate gland fluid

A
  • calcium
  • citrate ion
  • phosphate ion
  • clotting enzyme
  • slightly alkaline
  • profibrinolysin
57
Q

what percentage of semen is made from vas deferens, seminal vesicles and prostate gland fluids?

A

10% fluid = vas deferens
60% fluid = seminal vesicles
30% fluid from prostate gland

58
Q

what is the pH of semen

A

pH 7.5

59
Q

what component of the seminal vesicle fluid reacts with the female cervical mucus to make it more receptive for sperm movement

A

prostaglandins, a group of lipids with hormone-like actions

60
Q

what is capicitation

A

biochemical process occurring in the female reproductive tract, which enables sperm to fertilize an ovum

61
Q

describe capitation process

A
  1. uterine and Fallopian tubes fluid wash away male inhibitory factors
  2. membrane of sperm becomes more permeable to Ca2+ changing the activity of the flagellum
  3. Ca2+ causes changes to cellular membrane of the acrosome and allows release of acrosome enzymes (help penetrate egg coat)
62
Q

why do male inhibitory factors need to be washed away by uterine and fallopian fluids

A

they contain large amounts of cholesterol coating acrosome and preventing release of sperm ezymes

63
Q
A
64
Q

what is low sperm count also known as

A

oligozoospermia

65
Q

what are some causes of low sperm count

A
  • hormone imbalance
  • diet
  • undescended testis
  • structural issues
  • genital infections
  • exposure to chemicals
    etc
66
Q

3 causes of spermatogenesis sterility

A
  1. inflammation of testis resulting from mumps
  2. embryonic abnormalities
  3. excessive temps of testes degenerates spermatogonia
67
Q

what is the role of FSH and LH during the follicular phase

A
  • stimulate oocyte development and follicle growth
68
Q

what is the role of LH during the luteal phase

A
  • stimulates development and maintenance of corpus luteum
69
Q

during the ovulating phase, what secretes oestrogen

A

the follicle that has been ruptured

70
Q

what 2 hormones does the corpus luteum secrete during the luteal phase and what do either of them do

A
  • oestrogen , thickens endometrium
  • progesterone, increases number of blood vessels adds secretory glands in the endometrium
71
Q

ovarian cycle/ mestruration - day 0

follicular phase - day 7

ovulation - day 14

luteal phase - day 21

new follicular phase - day 28/0

A
72
Q

exogenous testosterone administration can have NEGATIVE effects on male fertility due to its NEGATIVE feedback on production of LH and FSH from the anterior pituitary gland, all of which are needed for SPERMATOGENESUS

A
73
Q
A