Physiology of Puberty Flashcards
(49 cards)
1
Q
Puberty:
A
- stage of physical maturation in
which an individual becomes
physiologically capable of pro-
creation - transition from childhood to
reproductive maturity
2
Q
Onset of Puberty:
A
- 8-13 in girls
- 9-14 in boys
3
Q
Physical changes in puberty:
A
- growth spurt
- secondary sex characteristics:
pubic & axillary hair, breasts, male
voice changes - menarche/spermatogenesis
4
Q
What are growth spurts?
A
short periods of time when child experiences quick physical growth in height and weight
5
Q
Growth Spurt: Signs:
A
- increased appetite: child’s
nutritional needs increase before
and during growth spurt - increase in bone and muscle
growth - increase in amount of fat stored in
the body
6
Q
Chronological Order of Puberty: Girls:
A
- growth spurt
- thelarche: breast development
- pubarche: pubic hair
- adrenarche: axillary hair
- menarche: menstruation
*not always true
7
Q
Chronological Order of Puberty: Boys:
A
- testicular enlargement
- penile length increases
- pubic hair
- growth spurt
- axillary and facial hair
- deep voice
8
Q
Which scale is used to describe the onset and progression of pubertal changes?
A
The Tanner Stages
9
Q
Tanner Stages: Difference between how girls and boys are rated?
A
- boys are rated for genital
development and pubic hair
growth - girls are rated for breast
development and pubic hair
growth
10
Q
Tanner Stages: Girl’s Breast Development:
A
insert slide
11
Q
Tanner Stages of Male External Genitalia:
A
insert slide
12
Q
Tanner Stages: Pubic Hair Growth:
A
13
Q
What is minipuberty?
A
- HPG axis is active in utero
- and first six months in boys
- first 2 years in girls
- **quiescent until the onset of
puberty
14
Q
HPG Axis:
A
- at onset of puberty
- hypothalamus starts to produce
pulsatile secretion of
gonadotrophin-releasing hormone
(GnRH) - stimulates the pulsatile release of
FSH and LH from the anterior
pituitary
insert diagram
15
Q
Role of Hormones in HPG Axis:
A
insert diagram
16
Q
Role of Testosterone in Puberty:
A
- increased muscle mass
- penile growth
- deepened voice
- pubic hair growth
17
Q
Role of LH in Puberty:
A
- stimulates testosterone production
- from interstitial cells of testes
18
Q
Role of FSH in Puberty:
A
- stimulates testicular growth
- enhances production of an
androgen-binding protein - by Sertoli cells, which are a
component of the testicular tubule
necessary for sustaining sperm cell
maturation
19
Q
Puberty: Extra-Gonadal Hormonal Changes:
A
- increased adrenal steroid
(androgen) from adrenal cortex - involved in secondary sexual
characteristics and growth of sex
accessory structures eg prostate - increased GH secretion from
anterior pituitary increases
elevation of insulin like growth
factor -> increased growth - increased TSH secretion from
anterior pituitary in both sexes - increases metabolic rate and
promotes tissue growth
20
Q
What categories of factors affect the timing of puberty?
A
- genetic
- environmental
- neuroendocrine
21
Q
What environmental factors can affect the timing of puberty?
A
- nutritional status
- chronic illness
- migration
- frequent infectious disease
- pollution
22
Q
Timing of Puberty: Neuroendocrine Factors:
A
- neuroregulation of puberty vis
neuropetides: kisspeptin,
neurokinin B and dynorphin A - at onset of puberty, stimulatory
drive of neurokinin B increases - results in kisspeptin production
- which regulates GnRH hormones
23
Q
Precocious Puberty: Ages:
A
- girls: <8yrs
- boys: <9 yrs
24
Q
Delayed Puberty: Ages:
A
- girls: >13 yrs
- boys: >14 yrs
25
Precocious Puberty:
- early/premature puberty
- presence of true pubertal features
at a young and inappropriate age
- either central/true precocious
puberty or peripheral/pseudo-
precocious puberty
26
Central/True Precocious Puberty:
- overview (3)
- causes (4)
- gonadotrophin dependent
- under 8 in girls, under 8 in boys
- premature activation of HPG axis
Causes:
- brain tumours
- raised intracranial pressure
- CNS malformation
- mutations of the kisspeptin
receptor hence dysregulation of
GnRH neurones
27
Central Precocious Puberty: Characteristics:
- secondary sexual characteristics
develop too early but not true
puberty
- premature thelarche
- premature adrenarche/pubarche
28
Peripheral Precocious Puberty:
- overview
- causes
- gonadotrophin independent
- girls <8yrs, boys <9yrs
Causes:
- ingestion of sex steroids
- hormone-producing tumours
(ovaries/testes)
- adrenal gland abnormalities ->
congenital adrenal hyperplasia
causing overproduction of sex
hormones
29
Precocious Puberty: Management:
- goals of managing precocious
puberty are to treat the underlying
cause and block
production/response of excess
hormones
- refer to endocrinologist to prevent
complications
- baseline measurement of
hormones: LH, FSH, Testosterone,
GnRH
- follow up
30
Precocious Puberty: Treatment:
- GnRH agonists halt the physical
progress of puberty
- produce initial increase in sex
hormones
- continued non-pulsatile
stimulation
- LH and FSG synthesis inhibited
- oestrogen and testosterone levels
decline
- GnRH antagonist blocks the
gonadotrophin receptors in the
pituitary
- inhibit LH and FSH release directly
- lacks the initial surge typical of
GnRH agonists
- treatment helps in very young
children with central precocious
puberty
31
Delayed/Late Puberty: Overview:
- more common in boys than girls
- most are not pathological
- family history common
- girls: >13yrs
- boys: >14yrs
32
Delayed Puberty: Causes:
- chronic illness: kidney
disease***search
- malnutrition -> eating
disorder/coeliac disease
- problem with ovaries, testes,
thyroid, pituitary
- genetic conditions: Turner
Syndrome, Klinefelter Syndrome
33
Delayed Puberty: Peripheral Defects:
- hypergonadotrophic
hypogonadism or primary
hypogonadism
- disorder of abnormal gonadal
function with decreased
testosterone in males and
oestradiol in females -> delayed
sexual development
34
Peripheral Defects: Hypergonadotrophic hypogonadism/primary hypogonadism: Causes:
- turner's syndrome
- post-malignancy
chemo/radiotherapy
- surgery can cause gonadal failure
- polyglandular autoimmune
syndromes
35
Turner Syndrome:
- female only genetic disorder
- 1 in every 1 in 2000 babies
- only one normal X sex
chromosome not two
- 45X (45 chromosomes instead of
46)
- primary and secondary female sex
characteristics are not fully
developed
- short stature, webbed neck, widely
spaced nipples, shield like thorax
36
Turner Syndrome: Treatment:
- growth and sex hormone
substitution
37
Turner Syndrome:
insert diagram
38
Delayed Puberty: Central Defects:
- congenital hypogonadotrophic
hypogonadism
- due to a problem with the pituitary
gland or hypothalamus
- decreased LH and FSH
- hence gonad will not be able to
produce sex hormones
Causes:
- hypothalamic lesions can lead to
low GnRH
- rare genetic mutations inactivating
FSH/LH or their receptors
39
Delayed Puberty: Central Defects: Diagnosis:
- low gonadotrophin levels
- poor response to stimulation with
GnRH stimulation test
**test checks how well the
pituitary gland works
- imaging can help
40
Delayed Puberty: Treatment Overview:
- treat underlying cause
- use meds short term to increase
hormone levels and trigger the
start of puberty
- hormone replacement therapy
41
Klinefelter Syndrome:
- mostly boys and men
- normal puberty and find out only
in adulthood..delayed puberty is
possible
- 47XXY
- karyotype shows extra
chromosome
- learning difficulties
Teenagers:
- taller than expected
- long limbs
- broad hips
- poor muscle tone and slow muscle
growth
- reduced facial and body hair
- hair grows later than usual
- small penis and testicles
42
Klinefelter Syndrome:
insert diagram
43
Klinefelter Syndrome: Treatment:
Testosterone Replacement Therapy
44
General Investigation for Children with Pubertal Issues:
- Bloods: LH, FSH, thyroid and
growth hormones -> provide
current situation not future
- Thyroid stimulates production of
growth factors and GH production
- physical examination will inform
about puberty status
- children within the normal range
for height and development are
not likely to have a medical
problem
- hand x-ray to determine likely
adult height
- ultrasound or MRI to check for
tumours
45
In terms of chronological order of puberty in boys, what is the first change?
- pubic hair
- axillary hair
- breast development
- testicular enlargement
testicular enlargement
46
"Papilla is elevated above the level of the chest wall."
As per Tanner stages of girls breast development:
- stage 1
- stage 2
- stage 3
- stage 4
Stage 1
47
Early or Precocious puberty in girls occur in ages less than:
- 8
- 9
- 10
- 11
8 years old
48
What is the chromosome number in Turner Syndrome?
- 46XY
- 45Y
- 45X
- 47XXY
- 45X
49
What chromosome number in Klinefelter Syndrome?
- 46XY
- 45Y
- 45X
- 47XXY
- 47XXY
