Hormone regulation of puberty Flashcards
1
Q
what physiological function is not needed for living
A
reproduction
2
Q
what causes sexual differentiation
A
two groups of steroid hormones
- androgens
- oestrogens
3
Q
two groups of steroid hormones that control sexual differentiaions
A
- androgens
- oestrogens
4
Q
what type of hormones are androgens and oestrogens
A
steroid hormones
5
Q
where are androgens synthesised
A
mainly in the testes & adrenal glands
6
Q
where are androgens released
A
mainly testes & adrenal glands
7
Q
primary biological androgen
A
testosterone
8
Q
male reproductive hormones
A
androgens
9
Q
what can androgens be converted to
A
oestrogens
10
Q
what are upstream of oestoens
A
androgens
11
Q
what is the female equivalent of androgens
A
oestrogens
12
Q
female reproductive hormones
A
oestrogens
13
Q
primary biological oestrogen
A
oestradiol
14
Q
where are oestrogens synthesised
A
ovaries or smal amounts in testes
15
Q
where are oestrogens released
A
ovaries or smal amounts in testes
16
Q
male and females are the ____ in early development
A
same
17
Q
mullerian duct
A
female
18
Q
wolffian duct
A
male
19
Q
male duct
A
wolffian duct
20
Q
female duct
A
mullerian duct
21
Q
what comprises the mullerian duct
A
fallopian tuve, uterus and cervix
22
Q
what comprises the wolffian duct
A
epididymis, vas deferens & seminal vesicles
23
Q
common gonadal primordian
A
ovaries and testes
24
Q
two embryonic duct systems
A
mullerian and wolffian
25
common external primordium
cliterus, vuvla and penis, scrotum
26
female phenotype
XX
27
male phenotype
XY
28
what is different about the Y chromosome
shorter then the rest
29
what signals to primordial gonads to develop testes
sry gene in Y chromosome
30
where is the sry gene
Y chromosome
31
what does the sry gene do
signals to the primordial gonads to develop testes
32
what causes the 1st sexual differentiation
sry gene , not a hormone
33
what do the testes produce in development
- testosterone to stimulate male genitalia deelopment and support Wolffian duct
- AMH which inhibits the Mullarin duct development
34
what does testosterone do in development
stimulates male genitalie development and supports the Wolffian duct
35
what stimulates male genitalie development and supports the Wolffian duct
testosterone
36
what does AMH do in development
inhibits the mullerian duct development
37
what inhibits the mullerian duct development
AMH
38
AMH
anti-mullerian hormone
39
do males or female follow the default pathway
females - they have no sry gene
40
what is the default pathway of gender development
primordial gonads develop to ovaries
| no AMH or testosterone is produced so mullerian duct and female genitalie develops
41
what occurs in the absence of sry gene
default pathway of female sexual differentiation
42
the absence of AMH allows for
development of Mullerian duct
43
ovaries produce AMH
false
44
what is the end point of puberty
the production of viable gametes
45
female gametes
ooctyes
46
male gametes
sperm
47
orderly sequence of physiological, anatomical & psychological landmarks
puberty
48
when does puberty occur
different ages for different individuals
49
pubertal changes
- adolescent growth spurt
- sex specific increases in growth rate
- changs in body comp
- development of mature reproductive function
50
what are better studies of puberty
longitudinal, because puberty timing is so variable making cross sectional studies poor
- cross sectional studies suggest that testes grow slowly over 10 years
- longitudinal studies correctly show they grow rapidly, but at different ages
51
The Tanner scale
staging of puberty using sclae of 1-5 based on physical development of external primary and secondary sex characteristics such as breasts development, genitalia development & pubic hair
52
two main events that cause increase in circulatig reproductive hormones and subsequent pubertal hormones
- adrenarche
| - increased HPG axis function
53
adrenarche
increased secretion of androgens from the adrenal gland
54
increased HPG axis function in puberty
increased HPG axis results in increased hormone secretion from the ovaries and testes
55
early stage of sexual maturation
adrenarche
56
where are androgens sectreted from
zona reticularis in the adrenal cortex
57
what does adrenarche cause
release of weak androgens in circulation
58
weak androgens
DHEA, DHEA sulphate, androstenedione
59
what effect do weak androgens have
directly & indirectly stimulate pubic changes
60
what does adrenarche not do
activate reproductive potential
61
adrogens relased from the adrenal effect which hair follices
pubic and axilla hair growth
62
axilla
armpit
63
what requires low levels of androgens for hair growth
axilla and pubic follicles
64
adrogens relased from the testes effect which hair follices
facial hair
65
what requires high levels of androgens for hair growth
facial hair
66
why doe beards only grow on men
they require high levels of androgens which only release from testes
67
what is the state of the HPG axis in children
inactive
68
when is the HPG axis inactive
childhood
69
switching on of the HPG axis =
puberty
70
the ovaries and testes are all capable of functioning prior to puberty. What signal do they await
signal from the hypothalamus
71
when will you have low steroid levels, low GnRH, low FSH and low LH
pre-puberty
72
precocious puberty
when puberty begins too early
73
causes of precocious puberty
inappropriate release of GnRH from the hypothalamus, usually a tumour. This triggers puberty earlier than intended
74
how does the hypothalamus trigger puberty
release of GnRH
75
GnRH
gonadatropin-releasing hormone
76
what triggers release of GnRH by the hypothalamus
kisspeptin
77
what are kisspeptins
peptides that encode the kiss-1 gene
range of AA lengths
collectively endogenous ligands for GPR54
78
Hypogonadotropic hypogonadism
impaired pubertal maturation and subsequent lack of reproductive function caused by problems wih kisspeptin or GPR54 knockout
79
GPR54
g-protein coupled receptor that binds to activate kisspeptin
80
what triggers kisspeptin release
not yet known
81
what does GnRH stimulate
release of LH and FSH to circulation
82
where are LH and FSH released from
anterior pituitary
83
action of LH in males
stimulates testosterone production in testes
84
action of LH in females
controls reproductive cycle & ovulation
| stimulates oestrogen
85
what stimulates testosterone production in testes
LH
86
what controls reproductive cycle & ovulation
| stimulates oestrogen
LH
87
FSH in males
stimulates growth and maturation of testes and spermatogenesis
88
FSH in femaes
stimulates growth and maturation of ovarian follicles
89
what stimulates growth and maturation of ovarian follicles
FSH
90
what stimulates growth and maturation of testes and spermatogenesis
FSH
91
LH levels prepuberty
low levels. not an immediate switch on
92
LH levels mid puberty
night-time increase in LH only
93
LH levels late puberty
regualr pulses of LH throughout day and night
94
what is testis volume directly linked to
testosterone levels
95
what causes increased testosterone release
testes growth
96
what does increased levels of tesosterone drive
secondary sexual characteristics such as facial hair and voice breaking
97
secondary sexual characteristics of males
facial hair and voice breaking
98
menarche
first period
99
what causes irregular cycles post menarche
- anovulation
- missing luteal phase
- variable oestrogen levels from developing cycles
100
when do cycles become regular
can take several years post menarch before ovulatory cycles become regular
101
adolescent growth spurt
- spike in height during adolsence
102
growth spurts
- rapid gain as baby
- spike drops
- adolescent spike = final growth spurt
103
what seperates growth plates
cartilage
104
what does cartilage do
grow new bone
105
when is there no more cartilage layers and what does this mean
end of puberty = no more growth
106
eunochoid gigantism occurs when
abscence of gonadal steroids. deficiency of oestrogn receptor
107
eunochoid gigantism
no growth spurt at adolesnce but also no epiphyseal fusion so growth can continue throughout adult hood
108
rare form of gigantism
eunochoid gigantism
109
cause of common form of gigantism
excess GH
110
feautres of eunochoid gigantism
underdeveloped sexual organs and lackof pubertal development
111
why is oestrogen crucuial in growth
it stimulates growth rate but the amount is critical
low oestrogen - growth
high ostrogen - fusion (good)
112
high levels of oestrogen cause what for a growth spurt
fusion
113
low levels of oestrogen cause what for a growth spurt
continued growth & osteoporisis
114
what causes sex specific changes in bone growth
hormonal activation of certain genes caused by different mechanisms to growth spurt
115
male changes in growth spurt
high levels of teststerone compared to oestradiol causes growth of the jaw, wideing of shouders & changes in shape of skull to give wider eyebrows
116
what causes growth of the jaw, wideing of shouders & changes in shape of skull to give wider eyebrows
high levels of teststerone compared to oestradiol
117
female changes in growth spurt
high oestradiol levels relative to testosterone causes widening and flattening of pelvis in preparation for child birth
118
what causes widening and flattening of pelvis in preparation for child birth
high oestradiol levels relative to testosterone
119
sexual dimorphism
differnces between sexes of the same species
120
what causes pubertal changes in body composition
hormonal changes in tissue development
121
males body composition changes
higher levels of testosterone causes marked increase in muscle mass giving greater strenghth
122
what causes marked increase in muscle mass giving greater strenghth for males
higher levels of testosterone
123
female body composition changes
higher levels of oestradiol results in increase in body fat
124
what results in increase in body fat for females
higher levels of oestradiol
125
3 phenotypic sexual dimorphism
bone growth
body composition
vocal pitch
126
what effects vocal pitch
androgens
127
how is vocal pitch changed
androgens stimulate growth of the larynx and thicking and lengthening of vocal chords
128
what stimulates growth of the larynx and thicking and lengthening of vocal chords
androgens
129
what are the sex differences in change in vocal pitch
males have greater levels of androgens so their voices will deepen more thant females
