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Flashcards in 3.1 Deck (55):
1

What is puberty?

Sexual maturation and growth completed resulting in ability to reproduce.

2

What happens in puberty?

Accelerated somatic growth
Maturation of primary sexual characteristic
Appearance of secondary sexual characteristics
Menstruation and spermatogenesis

3

What the thelarche?

Development of the breast

4

What is menarche?

First menstrual period.
Equivalent in males is first nocturnal erection and first ejaculation.

5

What is adrenarche

Onset of an increase in secretion of androgens and pubic hair growth.

6

When does puberty occur for males and females?

Males: 9-14 years
Females: 8-13 years

7

What is the first sign of puberty in males? Why?

Increase in testicle size due to FSH induced increase in seminiferous tubules. TEsticular volume up to 4ml

8

Describe the changes in male puberty.

Genital development - testicle enlargement
Adrenarche - pubic hair growth.
Spermatogenesis begins
Growth spurt (10cm/year)
Genitalia adult
Pubic hair adult

9

When does the growth spurt in males start? How fast is it?

About 12 months after the first signs of puberty.
10cm/year

10

Describe the female process of puberty.
What age does each occur at?

Thelarche - breast bud 8-11
Adrenarche - pubic hair growth 11-12
Grwoth spurt (9cm/year) 10-14
Menarche - onset of menstrual cycles 11-15
Pubic hair adult
Breast adult

11

What is the first sign of puberty in females?

Brest bud appearance - thelarche

12

Why are men on average taller than women?
What are the growth spurt rates? What ends the growth spurt?

Growth spurt is longer and slightly faster. Men = 10cm/year. Women = 9cm/year.
Epiphyseal fusion

13

How is pubertal development classified in girls and boys?

Tanner standard:
Girls: breasts, pubic hair, axillary hair, menarche.
Boys: Testicular volume, penis enlargement, pubic hair, axillary hair, spermarche.

14

How does growth change in puberty compared to before?

Growth velocity is 2-3 times greater than prepubertal.

15

WhatHow do hormones control puberty?

GnRH secretion is too low for reproductive function before puberty.
Gradual activation of GnRH increases frequency and amplitude of LH pulses.
Gonadogrophins stimulate secretion of sexual steroids leading to sexual maturation.
Extragonadal hormonal changes lead to somatic growth.

16

A rise in what hormones is associated with the beginning of puberty?

GnRH, FSH, LH
Initiated by brain

17

Describe the puberty hormonal changes in males.

Hypothalamus releases GnRH
LH and FSH release increases.
Spermatogenesis and androgen secretion.
Adrenals secrete androgens.
Androgens initiate growth of sex accessory structures (prostate) and male secondary sexual characteristics.
GH secretion increases
Sertoli secrete some oestrogen
TSH secretes increases:
Promotes tissue growth and increases metabolic rate.
Retention of minerals for growth.

18

Describe puberty hormonal changes in females.

Oestrogen induces secondary sexual characteristics:
Pelvis growth, subcutaneous fat
Growth of internal repro organs and external genitalia.
Androgen release by adrenal glands increases:
Growth of pubic hair
Lowering of voice
Growth of bone
Increased sebaceous gland secretion.

19

What initiates the first ovarian cycle?

LH surge
Usually insufficient to cause ovulation.

20

Describe the hormonal changes in the pre-follicular phase.

Corpus luteum absent
Follicles only partly developed
Secrete very little steroid or inhibin
O and P low
Little inhibition at hypothalamus or pituitary
FSH levels rise

21

Describe the hormonal changes at the mid-follicular phase.

Oestrogen levels rise
Inhibin levels rise.
Selective inhibition of FSH
No new follicles can develop.
Oestrogen exerts positive feedback at hypothalamus and pituitary
LH levels rise.

22

Describe the hormonal changes in ovulation

LH surge preceded by rise in oestrogen

23

Describe the hormonal changes post ovulation

Corpus luteum forms spontaneously
Begins to secrete oestrogen and progesterone.
Maintains suppression of FSH - no new follicles.
LH is also suppressed as positive feedback of oestrogen is inhibited by progesterone.

24

Describe the start of the new cycle.

Death of corpus luteum --> Corpus albicans
Leads to rapid fall in steroid levels
Stimulates menses
Relieves inhibition on FSH - follicular development.

25

How is adrenarche controlled?

Depends on androgen in both sexes
Testosterone in boys
From adrenal in girls.

26

What is the critical weight for menarche? What happens if body weight falls below this?

47kg
Reproductive cycle ceases.

27

Why has puberty got earlier through the generations? Evidence for this?

Earlier puberty due to improved nutrition, living conditions and healthcare.
Evidence:
Obese girls go through menarche early.
Malnutrition associated with delayed menarche.
Primary amenorrhoea common in lean female athletes.
Body fat set point is very noticeable in girls with fluctuating body weight.

28

When does the growth spurt start (Weight) in boys and girls?

30 kg in girls
55kg in boys

29

What does the growth spurt depend on?

GH and steroids in both sexes.

30

What causes growth spurt to end earlier in girls

Oestrogen closes epiphyses earlier.
Oestrogen is needed to initiate growth spurt but once levels reach a certain point, it causes epiphyseal fusion.

31

How is thelarche controlled?

Dependent on oestrogens.

32

How is genital development controlled in boys?

Testosterone

33

What is precocious puberty?

Onset of puberty 2SD before average age.
Before 8 in girls and before 9 in boys

34

What can precocious puberty be caused by?

Uncontrolled gonadotrophin/steroid secretion (gonadotrophin dependent)
Neurological causes (gonadotrophin independent)

35

Give some causes of gonadotrophin dependent precocious puberty.

Hormone secreting tumours
Gliomas, astrocytomas, hCG secreting germ cell tumours
CNS trauma or injury
Congenital disorders - hydrocephalus
Hamartoma of hypothalamus.
Exogenous exposure - therapeutic/accidnetal

36

Give some causes of gonadotrophin independent precocious puberty.

Inappropriate GnRH secretion caused by:
Pineal tumours
Meningitis.

37

How can meningitis cause precocious puberty?

Inflammation leading to early increase in GnRH release from hypothalamus, independent of HPG axis

38

What is precocious pseudo puberty? Cause? Consequence?

Appearance of secondary sexual characteristic early.
Due to increased production of female or male hormones independently of HPG axis.
Congenital adrenal hyperplasia --> androgens
Gonad matures without GnRH stimulation.
Levels of testosterone and oestrogen are elevated.

39

How to delay precocious puberty?

Testosterone inhibitor/GnRH anologues(competitive inhibitor)

40

What are the effects of precocious puberty on growth and stature?

Early growth spurt initially can cause tall stature but rapid bone maturation and sealing of epiphyses can cause linear growth to cease early, resulting in short adult stature.

41

What is bone age?

Accelerated growth is earliest sign of precocious puberty.
Can be determined with hand-wrist films and compared with standards for chronological age.

42

What is delayed puberty?

Initial changes are not present by
13 years in girls
14 years in boys

Pubertal development is inappropriate:
Interval between first signs and menarche of completion of male genital growth > 5 years

43

How can puberty be assessed?

Height, weight, genitals, body hair, bone age

44

What are causes of delayed puberty?

Hypergonadotrophic hypogonadism (Gonad failure)
Turner's 45, XO

Congenital hypogonadotrophic hypogonadism (gonad deficiency)
Hypothalmic pituitary lesions\Rare gene mutations inactivating FSH and LH

45

How does Turner's present?

Short stature
Gonadal dysgenesis
Skeletal abnormalities
Cardiac and kidney malfunction
Dysmorphic face
No mental/cognitive defect

46

How can delayed puberty present in girls? What is this due to if LH/FSH levels are normal?
LH/FSH high?
LH FSH low?

Primary amenhorrhoea - Failure to menstruate by 16 years

LH/FSH normal:
Imperforate hymen
Cervical stenosis

LH/FSH high
Ovaries are not responding to gonadotrophins

LH/FSH low
Hypothalmic/pituitary tumours

47

What is pre-menopause?

> 40 years?
Changes in menstrual cycle:
Follicular phase shortens
Ovulation early or absent
- Less oestrogen secreted
- Less negative feedback so LH and FSH levels rise
- FSH rises more due to loss of inhibit
- GnRH rises
- Reduced feedback --> reduced fertility

48

What is the menopause?

Cessation of the menstrual cycle.
49-51
Females run out of follicles
Oestrogen levels fall dramatically
Less negative feedback so FSH and LH rise
FSH dramatically due to no selective inhibition

49

What are the effects of menopause?

Hot flushes due to vascular changes
Uterus:
- Regression of endometrium
- Shrinkage of myometrium
Thinning of cervix
Vaginal rugae lost
Involution of breast tissue
Changes in skin
Reduction in bladder tone
Bone changes

50

What are the bone changes in menopause? How are they limited?

Reduction in bone mass by 2.5% per year for several years.
Reduced oestrogen enhances osteoclast ability to absorb bone.
Can lead to osteoporosis:
Increased risk of fracture.
Height/posture change.
Limited by bisphosphonates oestrogen therapy and calcium.

51

How do you treat hot flushes in post menopause?

Oestrogen therapy.

52

Describe HRT

Relieves symptoms of menopause
Can improve well-being
Oestrogen given orally or topically by patch or gel.
Usually a mix of oestrogen and progesterone.
Not advised for cardio protection

53

Give advantages of HRT

Can limit osteoporosis
Lowers risk of colon cancer
Lowers risk of vision loss and macular degeneration.

54

Give disadvantages of HRT

Increased risk of ovarian cancer
Endometrial cancer
Breast cancer
Thromboembolism
Stroke
BP

55

Why are oestrogen only preparations only given to women who have had hysterectomies?

Oestrogen causes endometrial hyperplasia in womb leading to cancer.
Progesterone inhibits this.