Sex hormones Flashcards
1
Q
What is the definition of puberty?
A
Maturation of reproductive organs; production of sex steroids (Oestradiol/Testosterone); development of secondary sexual characteristics and attaining the capability to reproduce
2
Q
What is thelarche?
A
Onset of breast development
3
Q
What is Gonadrche?
A
Activation of gonads by HPG axis
4
Q
What is menarche?
A
The first occurrence of menstural cycles
5
Q
What is adrenarche?
A
Adrenal androgen productiion
6
Q
When does adrenarche occur in comparison to Gonadrche?
A
onset 2 years before Gonadrche
7
Q
What is pubarche?
A
Onset of pubic hair development
8
Q
What are the main effects of oestradiol?
A
Breast development, hair growth (Pubic & axillary), sweat gland composition, skin oiliness/acne
Changes to external genitalia
9
Q
What is the first strage of thelarche?
A
Elevation of papilla
10
Q
What is stage 3 thelarche?
A
Further enlargement of breast and papilla, separation of their contours
11
Q
What is stage 5 of thelarche?
A
Adult: Mature breast, projection of papilla only as areola conforms to breast contour
12
Q
What are the main effect of testosterone?
A
Deepening of voice
Hair growth, pubic, axillary & facial
Sweat gland composition, skin oiliness and acne
Changes to externa genitalia
13
Q
For which gender is the age of onset earlier?
A
Females
14
Q
What is the age of onset for females?
A
8-13 years
15
Q
What is the age of onset for boys?
A
9-14 years
16
Q
Which stage occurs first in females? Adrenarche or menarche?
A
Adrenarche
17
Q
What is the first sign for females?
A
Thelarche
18
Q
What is the latest female pubertal sign?
A
Menarche
19
Q
What is the age of onset of puberty for males?
A
9-14 years
20
Q
What is the average testicular size for prepubertal males?
A
4 mls
21
Q
What is adult size of testicular volume?
A
15mls
22
Q
Which molecule is an adrenal androgen which increases with age?
A
DHEA
23
Q
Which gonadotrophs are released during gonadrche?
A
FSH & LH
24
Q
Which neurones are associated with the hypothalamus and control pulsatility?
A
Kisspeptin neurones
25
What is the role performed by kisspeptin neurones?
Regulate the pulsatile secretion of Gonadotrophin-releasing hormone (GnRH) from parvocellular hypothalamic neurones into the primary capillary plexus within the median eminence
26
Which circulation do hypothalamic hormones circulate within?
Hypophyseal-pituitary circulation
27
Which hormones are released upon GnRH stimulation?
LH & FSH
28
Which cells secrete LH and FSH?
Gonadotrophs
29
Where are gondatrophs situated?
Anterior pituitary gland
30
Which organs are stimulated by the action of LH & FSH?
Testes and ovaries
31
When is there an increase in GnRH pulsatility?
During Gonadrche there is an increased nocturnal GnRH pulsatility, towards a new equilibrium steady rate during adulthood
32
What happens to the HPG axis during childhood?
There is quiescence
33
What is mini puberty?
Stimulates the early development and maturation of sex-organs --> Increased risk of Mal-descent of the testes & micro-penises
34
What is the consequences of mini-puberty?
Mal-descent of testes and micro-penises
35
What is the consequence of a continuous non-pulsatile administration of GnRH?
Causes decreased LH/FSH secretion
36
Delayed onset of puberty is more common with which gender?
Males
37
What term describes an early onset of puberty?
Precocious
38
What is the precocious age of onset for females?
<8 years
39
What is the average delayed age of onset for males?
14 years
40
When does menarche occur after thelarche?
2.3 years, immediately after peak height velocity
41
What is the mean age for menarche?
12.7 years (Range 10.7-16.1 years)
42
What is amenorrhoea?
Absence of periods
43
What is the definition of primary amenorrhoea?
Later than 16 years is regraded as abnormal, delayed menstrual cycle onset
44
What is secondary amenorrhoea?
Common for irregular/anovulatory periods for initial 18 months. Periods begin, however cease for 3-6 months
45
What is the average number of annual periods with patients experiencing secondary amenorrhoea?
3
46
What is oligo-menorrhoea?
Irregular or infrequent periods > 35 day cycles (4-9 cycles annually)
47
How long is a standard menstrual cycle?
28 day cycle
48
What is the first phase of the menstrual cycle?
Follicular phase
49
Which hormone rises during the follicular phase?
FSH
50
What is the average number of follicles that grow during the follicular phase?
2-3 follicles
51
What hormones are produced by the follicular phase?
Inhibin and E2
52
What effect is exerted by inhibin and E2 on FSH secretion?
Negative feedback effect on FSH secretion on the hypothalamus and on the anterior pituitary gland
53
What happens to non-dormant follicles during the follicular phase?
They undergo atresia
54
What term is used to describe a dominant follicle?
Graafian follicle
55
What happens to the E2 concentration during the follicular phase?
E2 concentration continues to increase, positive feedback switch exerted by E2
56
What effect is exerted by a positive feedback switch by E2?
Induces luteinising hormone surge
57
What happens due to the induction of LH?
Stimulates ovulation, secretion of the mature secondary oocyte from the Graafian follicle
58
What is the term used to describe the remnant follicle upon ovulation of secondary oocyte?
Corpus luteum
59
What phase follows the follicular phase?
Luteal phase
60
Which hormone develops the corpus luteum?
LH
61
Which hormone is released from the corpus luteum?
Progesterone
62
Which hormone maintains the endometrium lining?
Progesterone
63
What test can be conducted to identify ovulation?
Progesterone level test for mid-luteal phase
64
What effect does progesterone have?
Maintains endometrium lining
65
What effect does decreased progesterone have on FSH?
Reduced negative feedback, stimulates FSH levels, oestradiol is secreted
66
Why does the corpus luteum degrade?
Due to absent HCG stimulation
67
The reduction of progesterone results in what?
Shedding of the endometrium lining - mensural cycle occurs
68
What hormone is tested in pregnancy tests?
Beta HCG
69
Which receptors are activated by beta HCG?
LH and FSH receptors - continues to support the corpus luteum - secretes progesterone
70
Which hormonal receptor is stimulated by elevated progesterone levels?
TSH receptor --> Thyrotoxicosis
71
What happens to pulsatility due to progesterone release?
Negative feedback, therefore decrease pulsatile effect of GnRH
72
What is hypogonadism?
Is concerned with decreased oestrogen and testosterone concentrations within and females respectively --> Associated with reduced gonadal function (Trauma to organs, infections (Mumps))
73
What is primary hypogonadism in males?
Reduction in testosterone (low E2) secretion from testes, and reduced oestrogen secretion from ovaries. Subsequent reduction in gonad-hormones result in reduced exertion of negative feedback onto the gonadotrophs -- increased lH/FSH
74
Describe the LH/FSH levels for patients with primary hypogonadism?
LH/FSH levels are elevated
75
During menopause which hormones are at lower concentrations?
E2, oestrogen and inhibin
76
During menopause which hormones are elevated?
FSH and LH
77
What are the common causes of primary hypogonadism in males?
Infection
Trauma
Cancer of testes
78
What is secondary hypogonadism?
Due to hypothalamic and pituitary disorders -> Reduced secretion of FSH & LH from anterior pituitary gonadotrophs
79
How can a pituitary adenoma lead to secondary hypogonadism?
Elevated production of prolactin, exerts negative inhibition on kisspeptin causing downstream inhibition and pulsatility on GnRH -> Reduced gonadotrophin release --> Low e2 and testosterone, oestrogen
80
What is menopause?
Oestradiol deficiency
81
What are 7 main consequences of menopause?
Skin dryness; hair thinning
Hot flushes; sweating; sleep disturbances
Mood disturbance
Osteoporosis: Decreased bone mineral density (BMD); E2 stimulates osteoblasts.
Sexual dysfunction: Vaginal dryness, decreased libido
Weight gain
Amenorrhoea: No periods for 1 year+; cessation of fertility; climacteric: Irregular periods in the years approaching menopause.
82
What are the treatments for menopause?
Oestrogen replacement --> Hormone replacement therapy
83
How can hyperplasia cancer be reduced during hormonal therapy?
Oestrogen stimulates the endometrium; combination of progesterone facilitates endometrium maintenance Preventing the risk of endometrial hyperplasia/cancer.
84
What is the median age for menopause?
51 years
85
When does gametogenesis occur?
Occurs at puberty (gonadrche)
86
How long is the spermatogonia pool lifespan?
Poo available for subsequent spermatogenic cycles throughout life generating continuous fertility
87
What meiotic phase are primary oocytes within primordial follicles halted in?
Prophase 1
88
What happens to primordial follicles?
Undergo atresia
89
Which hormone is secreted by Sertoli cells within ovaries can be used to test ovarian reserve?
Anti-Mullerian hormone (AMH)
90
What happens during pre-menopause?
Premature ovarian failure (POF), conception can happen in 20%
91
How is premenopausal diagnosed?
Elevated FSH > 2,5iU/L
92
What are the 3 main causes of pre-menopause?
Autoimmune
Genetic :Fragile X syndrome, Turner's
Cancer therapy: Radio/chemo therapy
93
What does the free testosterone hypothesis suggest?
Sex-hormone binding globulin is reduced and becomes unavailable , thus reducing free testosterone availability
94
Which plasma protein is bioactive testosterone bound to?
Albumin
95
When is testosterone levels high during the day?
During the morning
96
When should testosterone levels be measured?
before 11am
97
What pattern is exhibited by testosterone?
Diurnal rhythm
98
What are the main symptoms of testosterone deficiency?
Symptoms of deficiency: Sexual dysfunction (Reduced libido); erectile dysfunction (loss of early morning erections); hair growth (frequency of shaving); energy levels; mood disturbances, body composition (Increased fat, reduced muscle mass, gynaecomastia (breast enlargement in males)); spermatogenesis (high levels of intratesticular testosterone required); bone health (Conversion to oestrogen).
99
Which enzyme converts testosterone into 17B-estradiol?
Aromatase
100
Which enzyme converts androstenedione to oestrogen?
Aromatase
101
Which enzyme converts testosterone into DHT?
5-alpha-reductase
