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Reproduction (Semester 4) > 4.2: Puberty and Menopause > Flashcards

4.2: Puberty and Menopause Flashcards

1
Q

When are the primary sexual characteristics developed?

What are these?

A

Before birth:

  • these are associated with reproduction
  • ducts, external genitalia, ovaries, uterus, testis
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2
Q

What 3 things do puberty cause

A

Puberty:

  • Secondary sexual characteristic development
  • Gamete production
  • Behavioural changes necessary for reproduction
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3
Q

When do secondary sexual characteristics develop

What are these?

A

Develop at puberty

  • these are things like underarm hair, breasts, pubic hair, and facial hair
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4
Q

What is the name for the specific sequencing of events that occurs at puberty?

Which gender begins and ends puberty earlier?

A

The Tanner staging

there is variable age of onset between individuals but girls tend to begin and end puberty before boys

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5
Q

What controls puberty?

A

Controlled by activation of HPG axis due to increased hormone levels and gamete production

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6
Q

What are the 5 stages of the ‘Tanner staging’?

A

1) Hormone release but no physical changes
2) First physical changes:

  • girls develop breast buds
  • boys undergo testes and scrotum enlargement

3) Growth spurt, continued physical changes

  • girls develop fat around hips
  • boys have voice cracks and nocturnal ejaculations (but still NOT fertile until stage 4)

4) Key functional events: girls

  • girls have first period
  • boys begin spermatogenesis (now fertile)

5) Adult physical appearance and function:

  • girls have regular periods/ovulation
  • boys have facial hair and musculature
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7
Q

What is the age of puberty onset in females?

List the 6 stages of Tanner that occur

A

Ages 8-13 years

1) breast bud (thelarche)
2) pubic hair growth begins (adrenarche)
3) growth spurt
4) onset of menstrual cycles (menarche)
5) continued pubic hair to that of an adult
6) continued breast growth to that of an adult

Note: there is overlap between all stages

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8
Q

What hormones trigger breast and female genital development in females?

What hormones trigger pubic and axillary development in females?

A

Breast and genital development: influenced by gonadal oestrogens

Pubic and axillary hair: development is controlled by androgens from the adrenals

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9
Q

At what tanner stage of breast development is the FIRST pubertal sign observed in females?

What is this?

A

Stage 2 of breast development

When the breast bud is palpable under areola

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10
Q

Describe the five stages of breast development

A

1) no glandular breast tissue palpable
2) breast bud palpable under areola (1st pubertal sign in females)
3) breast tissue palpable outside areola; no areolar development
4) areola elevated above contour of the breast, forming “double scoop” appearance
5) areolar mound recedes into single breast contour with areolar hyperpigmentation, papillae development and nipple protrusion

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11
Q

What is the age of puberty onset in males?

List the 6 stages of Tanner that occur

A

Age: 9-14

1) genital development begins, testes before penis
2) pubic hair growth
3) growth spurt
4) spermatogenesis begins
5) adult genitalia formed
6) pubic hair that of an adult

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12
Q

What hormone controls development of genitalia, body hair and deepening of voice?

At what tanner stage is the FIRST pubertal sign observed in males?

A

Controlled by testicular androgens

Stage 2 of male penis development: 4-8 ml (or 2.5-3.3
cm long)

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13
Q

What are the Tanner stages for male penis and scrotal development?

A

1) testicular volume < 4 ml OR long axis < 2.5 cm
2) testicular volume of 4-8 ml OR 2.5-3.3 cm long
3) testicular volume 9-12 ml OR 3.4 - 4cm long
4) testicular volume 15-20 ml OR 4.1-4.5 cm long
5) testicular volume > 20 ml OR > 4.5 cm long

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14
Q

What are the 5 Tanner stages for male and female pubic hair development?

A

1) no hair
2) downy hair
3) scant terminal hair
4) terminal hair filling the entire triangle overlying the pubic region
5) terminal hair extending beyond the inguinal crease onto the thigh

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15
Q

What cell type is responsible for growth and what terminates it in both sexes?

A

chondrocyte proliferation at the ends of long bone are responsible for growth

In both sexes oestrogen terminates growth by fusion of the epiphyseal growth plates in long bones

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16
Q

Why are males generally taller than females?

A

Female growth spurts occur earlier and are shorter (partly because they have more estrogen which stimulates fusion at the epiphyseal plate)

Men are taller as their growth spurt occurs later, is longer and occurs at a slightly higher growth rate

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17
Q

Can most parts of the reproductive system work before the normal age of puberty and why?

A

Most parts of the reproductive system CAN work before puberty but don’t.

This is because hormone levels are low- specifically due to low GnRH secretion

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18
Q

What is precocious puberty and what causes it, include an example?

How might you treat this?

A

Precocious puberty is early puberty due to earlier activation of GnRH secretion.

This can be caused by multiple influences such as weight

Delay by giving GnRH inhibtors

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19
Q

What causes delayed puberty?

How may you treat this?

A

Most of the time children simply develop later than their peers

BUT delayed puberty can sometimes be caused by

  • chronic or genetic disorders
  • hormonal disorders
  • radiation or chemotherapy
  • eating disorders or excessive exercise
  • tumors
  • certain infections

Can be treated with exogenous pulsed infusions of GnRH

20
Q

In terms of the HPG axis, what initiates the onset of puberty?

A

The anterior pituitary responds to stimulation by GnRH long before puberty normally occurs BUT GnRH secretion is low

Puberty occurs when the brain initiates “pulsatile” GnRH secretions once the hypothalamic mechanisms ‘mature’ under other influences

21
Q

List 3 signals that influence GnRH neurons to increase secretion

A

1) other neurones
* KISS 1 neuron is a key player: releases the Kisspeptin neuropeptide
2) Environmental effects such as body weight
* Influence KISS 1 neurones or GnRH neurones directly
3) ‘feedback’ from gonadal hormones
* Gonadal steroids

22
Q

What is the MAIN factor that stimulates the hypothalamus to steadily increase GnRH secretions once matured?

How does it do this?

A

Various factors influence timing of puberty but the the MAIN determining factor is body weight.

The plasma concentration of leptin (released from adipocytes) stimulates the Kisspeptin neuron to signal the hypothalamus to increase GnRH secretion by indicating the initial body weight

23
Q

What is the critical weight for menarche in girls?

What may happen if weight falls significantly below this and give an example of when this may be the case

A

Critical weight for menarche in girls is 47kg

If body weight falls significantly below this reproductive cycles cease

  • e.g. anorexia, some athletes
24
Q

What is the critical weight for growth spurt in boys vs girls?

A

Critical weight for growth spurt in boys is 55kg

Critical weight for growth spurt in girls is 30kg (remember females tend to begin earlier than males)

25
Q

The general trend over the past 150 years has showed an earlier onset of menarche in women, give 3 reasons why this may be the case?

A

1) Improved diets etc.
2) Improved health/reduced disease
3) possible input of exogenous hormones e.g. in food

26
Q

How does melatonin affect puberty and what influences it?

What specific type of tumour can cause the opposite effect and why?

A

Melatonin is released in response to darkness and stimulates the Kisspectin neuron to increase GnRH ➞ stimulates puberty

In prepubertal years we have a higher sensitivity to light, so if overexposed to light (eg. TV, sunlight), it may result in decreased melatonin production, decreased GnRH and thus delayed pubery

A pineal tumour (type of brain tumor) can initiate early puberty (precosious puberty) because the pineal gland makes melatonin

27
Q

The timing of puberty is also very influenced by the brain, list 3 signals that promote maturation of the central mechanisms in the brain

What do mutations in these genes cause?

A

1) Kisspeptin neuropeptide signalling
2) Glutamate signalling
3) GABA downregulation

Mutations in genes for these proteins/receptors impact puberty onset.

28
Q

Genetic factors may also influence puberty timing, give two genetic predispositions to undergoing an earlier puberty?

A

1) african american girls undergo puberty earlier than caucasians
2) If mothers went through puberty later, daughters are likely to also

29
Q

At what age is ‘precocious puberty’ defined as in boys vs girls?

In which gender is it more common in and in which gender is it more likely to be pathological?

List 3 potential causes

A
  • Boys: classified as signs of puberty before age of 9
  • Girls: classified as igns of puberty before age of 8

More commonly occurs in girls but more likley to be pathological in boys

Cause: often unknown but can be due to:

1) neurological issues ➞ effect central maturation signalling (eg. pineal tumours, meningitis)
2) Uncontrolled gonadotrophin or steroid secretion (hormone secreting tumours of pituitary/gonads)
3) Genetics

30
Q

How might you treat precocious puberty?

A

Blocking gonadotrophin release from the pituitary

31
Q

Give one sign of delayed puberty in boys vs girls

Which gender is it more common in?

List 3 possible causes

A
  • Boys: no sign of testicular development by age 14
  • Girls: no sign of breast development by age 13 OR breast present but NO menarche by age 15

More common in boys

Cause unknown but could be:

1) Linked to malnutrition and chronic illness
2) Issues with gonads, thyroid or pituitary glands
3) Genetic conditions e.g. androgen insensitivity, Klinefelters syndrome

32
Q

How might you treat delayed puberty?

A 
Depending on the cause, could be treated by pulsatile
GnRH infusions (exogenous)
33
Q

What happens on a hormonal level prior to puberty?

Compare levels and timings of these hormones in males vs females

A

Onset of puberty a/w a rise in pulsatile GnRH secretion (Initially at night), followed by a steady rise in FSH & LH secretion

Girls: plasma levels of FSH and LH rise gradually from about 7 years to reach adult levels at/soon after menarche. Oestrogen levels rise steadily, until at the beginning of menstrual cycles (fluctuations in this following menarche are associated with the ovarian cycle)

Boys: FSH and LH levels rise later, to reach adult levels around 16 years of age, this is a/w a steady rise in testosterone levels

In both sexes weak androgens are secreted from adrenal cortex

34
Q

How can we test puberty progress if there are concerns regarding delay/potential signs in young children

A

Test hormone levels (particularly GnRH, FSH and LH)

35
Q

List the hormones involved in the following developmental landmarks of puberty in both sexes:

a) pubic and axillary hair
b) genital development
c) breast development in females
d) gamete development
e) growth spurt
f) larynx and laryngeal muscle development in males

A

a) adrenal androgens in females, androgens in males
b) testosterone (males), oestrogen (females)
c) oestrogen
d) FSH, LH and gonadal steroids in both sexes
e) GH and steroids in both sexes, oestrogen closes the epiphyses (earlier in girls)
f) Testosterone

36
Q

At what age does pre-menopause usually begin?

What 4 changes happen to the menstrual cycle during this stage

What can be measured as a marker of this?

A

typically begins around age 40:

1) Follicular phase shortens, ovulation early or absent
2) Less oestrogen secreted
3) LH & FSH levels rise due to reduced feedback, FSH more so
4) Reduced fertility

Hormone levels can be used as a marker

37
Q

What is the average age that menopause occurs and what marks the start of menopause?

Give 3 possible causes for this to occur?

A

Average age is around 49-50years (but varies) marked by ceasing of the menstrual cycle

Cause not clear but could be due to:

  • follicle supply exhausted- not completely
  • Insufficient oestrogen levels for positive feedback
  • ovaries no longer able to respond to gonadotrophins
38
Q

What are the hormonal changes that occur to the menstrual cycle during menopause and why?

A

1) ostrogen levels fall dramatically: because they are no longer being produced by ovarian follicles as the follicle supply is near exhausted
2) FSH & LH levels rise (FSH dramatically): because there is no negative feedback via gonadal steroids and inhibin hence the HPG axis is broken

39
Q

Name four common symptoms experienced as a result of menopause

A

1) Hot flushes due to vascular changes
2) Irritability, depression, tension, anxiety
3) Reduction in size of uterus and breasts
4) Increased bone catabolism due to decreased oestrogen leading to brittle bones (osteoporosis)

40
Q

What are the effects of the menopause on vascular changes and what symptom does this result in women feeling?

A

There are transient rises in skin temperature and flushing

Results in “hot flushes”

Relieved by oestrogen treatment

41
Q

What are the effects of menopause on reproductive tissues and why?

A

Reproductive tissues are oestrogen sensitive tissues and hence decreased oestrogen has the following effects:

  1. uterus (regression of endometrium +shrinkage of myometrium)
  2. thinning of cervix
  3. vaginal rugae lost
  4. Involution of some breast tissue
  5. changes in skin
  6. changes in bladder
42
Q

What are the effects of menopause on bone mass?

What can this lead to and how can it be treated?

A

Less oestrogen increases osteoclast activity leading to increased reabsorption relative to production (oestrogen normally inhibits osteoclasts)

This can lead to type 2 osteoporosis and a greater risk of fractures later in life

Can be limited by oestrogen therapy

43
Q

What defines post menopause?

A

No periods for 12 consecutive months

44
Q

What is HRT and what is it’s purpose?

How is its administered?

A

Hormone replacement therapy:

  • relieves symptoms of menopause which can improve well-being
  • can limit osteoporosis

Oestrogen is given orally or topically by patch or gel

Note: No longer recommended for first line protection and not advised for cardioprotection

45
Q

What defines the end of reproductive life in males and how does this compare to females?

What specifically happens in males?

A

There is NO obvious ‘event’ equivalent to menopause in females

Instead there is a gradual decline in semen volume, sperm motility and quantity throughout adult life in males.

BUT sperm production is continuous throughout life (hence new fathers in 60s & 70s is not uncommon)

With age there are other factors that may reduce chance of conception in males during later life… Eg. erectile dysfunction

Reproduction (Semester 4) (20 decks)

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