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3- Reproduction > Hormones and Regulation > Flashcards

Hormones and Regulation Flashcards

1
Q

Puberty

A

Developmental changes a child undergoes to become sexually mature and physiologically ready for reproduction

Females:8-14
Males: 10-16

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2
Q

Control of puberty and reproductive system

A

Hormones of Hypothalamic-Pituitary-Gonodal Axis

Hypothalamus releases GnRH in pulsatile manner.
stimulates release of FSH and LH from anterior pituitary gland

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3
Q

Role of FSH and LH

A

Act on gonads to stimulate synthesis and release of sex steroid hormones nd support gametogenesis

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4
Q

Rise in FSH

A

Increase in oestrogen synthesis and oogenesis in females and onset of sperm production in males

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5
Q

Rise in LH

A

Stimulates an increase in production of progesterone in females and an increase in testosterone production in males

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6
Q

Physical Changes during puberty - Females

A

Thelarche
- Breast development

Pubarche

  • Growth of hir in pubic area
  • mediated by testosterone

Menarche

  • First menstrual period
  • Arises due to increase in FSH and LH
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7
Q

Physical Changes during puberty- males

A

Genital Changes

  • Increase in testicular size
  • Growth of scrotal skin
  • Growth of panic

Pubarche

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8
Q

Growth spurt

A

Product of complex interaction between gonadal sex steroids (estradiol/ testosterone), GH and insulin-like growth factor (IGF-1)

GH levels rise in puberty due to increase in sex steroids and their positive effect on pulsatile release of GH from anterior pituitary gland
RIse in GH causes a rise an anabolic hormone IGF-1, csauses somatic growth via its metabolic actions

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9
Q

Precocious puberty

A

appearance of secondary sexual characteristics before

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10
Q

Causes/ types of precocious puberty

A

Iatrogenic
- result of exposure to exogenous oestrogen

True/ complete
- early maturation of HPG axis resulting in high level of GnRH, FSH and LH. My be due to CNS lesions near or in posterior hypothalamus, CNS neoplasms, harmatomas, primary hypothyroidism

Incomplete
- increased level of oestrogen in girls and androgens in boy that are independent of GnRH

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11
Q

Delayed/ absent puberty

A

Absence of secondary sexual characteristics by age of 13 in girls or 16 in boys

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12
Q

Causes of delayed/absent puberty

A

Hypogonadotrophic hypogonadism

Hypergonaadotropic hypogonadism

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13
Q

Conditions associated with delayed/ absent puberty

A

Turner’s Syndrome (45 XO)
Klinefelter’s Syndrome (47 XXY)
Androgen Insensitivity syndrome
Kallmann Syndrome

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14
Q

Normal duration of menstrual cycle

A

21-35 days

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15
Q

regulation of menstrual cycle

A

Hypothalamus, anterior pituitary and ovaries

GnRH from hypothalamus stimulates LH and FSH release from anterior pituitary gland.

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16
Q

Role of LH and FSH in menstrual cycle

A

Gonadotrophins that act primarily on the ovaries.

FSH: binds to granuloma cells to stimulate follicle growth, permit conversion of androgens (from theca cells) to oestrogen and stimulate inhibit secretion

LH: acts on theca cells to stimulate production and secretion of androgens.

17
Q

Feedback systems controlling menstrual cycler

A

Moderate oestrogen levels exert negative feedback on HPG axis.

High oestrogen levels (in absence of progesterone) positively feedback on HPG axis.

Oestrogen in presence of oestrogen exerts negative feedback on HPG axis.

Inhibin selectively inhibits FSH at anterior pituitary.

18
Q

Ovarian cycle

A

Follicular Phase
Ovulation
Luteal Phase

19
Q

Follicular Phase

A

Beginning of new cycle.
Follicles begin to develop independently of Gonadotropins.
Increase in FSH and LH
Stimulate follicle growth and oestrogen production

Rise of oestrogen- negative feedback reduces FSH levels.
Only one follicle can survive

Follicular oestrogen becomes high enough to potentiate +ve feedback at HPG- increasing GnRH and Gonadotropins

LH levels increase.

Granulosa cells luteinised and become receptors for LH

20
Q

What do non-dominant follicles form

A

Polar bodies

21
Q

Ovulation

A

In response to LH surge, follicle ruptures and mature oocyte is assisted to Fallopian tube by fimbria.
Remains viable for fertilisation for ~24 hours.
Following ovulation, follicle remains luteinised, secreting oestrogen and progesterone,
Reverts to -ve feedback on HPG axis.
Negative feedback + Inhibin ->stalls cycle in anticipation of fertilisation

22
Q

what tissue forms in ovary at site of rupture follicle following ovulation
+ what is its role

A

corpus luteeum,

Produces oestrgoens, progesterone and Inhibin to maintain conditions for fertilisation and implantation

23
Q

Luteal phase

A

Formation of corpus lute. At end of cycle in absence of fertilisation, corpus luteum spontaneously regresses after 14 days.
Significant fall in hormones, relieving negative feedbackl, resetting HPG axis

24
Q

Fertilisation

A

If fertilisation occurs, syncytiotrophoblast of embryo produces HcG exerting luteinising effect -> maintaining corpus luteum.
Supported by placental HcG and produces hormones to support pregnancy.

25
Q

Uterine cycle phases

A

proliferative
secretory
menses

26
Q

Proliferative phase

A

Runs alongside follicular phase.
Prepares reproductive tract for fertilisation and implantation.

Oestrogen inhibits fallopian tube formation, thickening of endometrium, increased growth and motility of myometrium and production of thick alkaline cervical mucous.

27
Q

Secretory phase

A

Runs alongside luteal phase

Progesterone stimulates

  • further thickening of endometrium into glandular secretory form.
  • thickening of myometrium -reduction of motility of myometrium
  • thick acidic cervical mucus production
  • changes in mammary tissue
  • other metabolic changes
28
Q

Menses

A

Marks beginning of new menstrual cycle.
Occurs in absence of fertilisation once corpus luteum has broken down and internal lining of uterus is shed

menstrual bleeding usually lasts 2-7 days with 10-80ml blood loss

29
Q

Dysmenorrhoea

A

Painful periods

30
Q

Endometriosis

A

Growth of endometrial tissue outside of the uterus

31
Q

menopause

A

end of female reproductive life.
physiological process which begins as perimenopause at ~45 and progresses until final menopause’s and end of fertility

Menopause is defined when a women has had amenorrhoea for 12 months.

32
Q

early menopause

A

before 45 years

33
Q

perimenopausal

A

women progressing towards menopause

34
Q

hormone changes during menopause

A

reduction of circulating oestrogen
- reduced sensitivity of ovary to circulating gondaotropins

Increase in anovulatory cycles

Significant increase in FSH and lH

  • low levels of circulating oestrogen
  • decrease in developing follicle reduces amount of Inhibin release
35
Q

vasomotor changes during menopause

A

hot flushes

associated with peripheral vasodilation and transient rise in body temperature.

Pulsatile LH relese influences central temperature control

36
Q

urogenital changes during menopause

A

decrease in oestrogen
- marled atrophy of vagina and thinning of myometrium.
can result in dyspareunia

Bladder and urethra can also atrophy. Lead to symptoms of urinary incontinence and increase in UTIs

37
Q

bone density in menopause

A

oestrogen protects bone mass and density through reducing activity of osteoclasts.
Drop in oestrogen causes increase in bone resorption.

results in acceleration of age-related loss of bone density and increased frequency in fractures.

38
Q

ischaemic heart disease and menopause

A

oestrogen offers protective effect against her disease.

Oestrogen reduces levels of LDL cholesterol whilst raising HDL cholesterol.

3- Reproduction (15 decks)

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