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BRS ENDOCRINOLOGY > 1a Sex Hormones > Flashcards

1a Sex Hormones Flashcards

1
Q

What are the four hallmarks of puberty?

A
  1. Development of secondary Sexual Characteristics
  2. Maturation of Reproduction Organs
  3. Obtaining ability to reproduce
  4. Production of sex-steroid hormones
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2
Q

What are the two main sex steroid hormone?

A

Oestradiol and Testosterone

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3
Q

What is meant by thelarche?

A

The onset of breast development

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4
Q

When is meant by menarche?

A

The onset of menstruation

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5
Q

What is meant by Pubarche?

A

The onset of pubic hair development

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6
Q

what scale is used to meant Breast development in females?

A

tanner scale

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7
Q

What is gonadarche?

A

The onset of the activation of the gonads by the HPG axis

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8
Q

What is meant by spermarche?

A

The onset of spermatogenesis

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9
Q

When does adrenarche occur?

A

Starts around 2 years before gonadarche

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10
Q

What is adrenarche?

A

onset of adrenal androgen production

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11
Q

What is the first sign of puberty in males?

A

Increases in testicular volume

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12
Q

What is the first sign of puberty in women?

A

Thelarche

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13
Q

What is often used to see what the testicular volume should be at each stage of life?

A

Prader- Orchidometer

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14
Q

What hormone leads to the development of secondary sexual characteristics in females?

A

Oestradiol

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15
Q

What are the secondary sexual characteristics in females?

A

Breast Development
Hair growth (pubic and axillary)
Changes to sweat gland composition (skin becomes more oily and acne develops)
Changes to external genitalia

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16
Q

What hormone results in the development of secondary sexual characteristics in males?

A

testosterone

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17
Q

What are the secondary sexual characteristics of boys?

A

Increase in testicular volume
Pubic then Facial and Axillary hair development
Voice deepening

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18
Q

At what age does adrenarche occur in females?

A

6-9 Years Old

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19
Q

At what age does adrenarche occur in men?

A

7-10 years

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20
Q

What is the late sign of puberty in girls?

A

Menarche

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21
Q

At what age does puberty typically occur at in females and males?

A

Females - 8-13 Years
Male - 9-14 Years

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22
Q

What is an adult testicular volume?

A

> 15mLs

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23
Q

What is the average early pre-pubertal testicular volume?

A

Less than 4mLs

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24
Q

What are the adrenal androgens?

A

DHEA
Androstenedione
Testosterone

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25
Q

How do the levels of FSH and LH change as girls and boys progress through the Tanner stages of development?

A

The serum levels of FSH and LH Increase

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26
Q

What is GnRH?

A

Gonadotrophin Releasing Hormone

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27
Q

What term is used to describe the secretion of GnRH?

A

Pulsatile - comes in waves

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28
Q

Why must GnRH secretion be pulsatile?

A

The continuous pulsatile administration of GnRH causes decreased LH/FSH secretion

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29
Q

What changes occur during mini-puberty?

A

Testicular descent out the stomach
Penile length increases
Sertoli cell maturation

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30
Q

When does the HPG axis undergo quiescence?

A

During childhood, before the onset of puberty

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31
Q

During puberty, what happens to the GnRH pulsatility?

A

There is increased nocturnal GnRH pulsatility

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32
Q

Describe how the HPG axis works?

A

Kisspeptin neurones associated with the hypothalamus regulate the pulsatile secretion of GnRH from parvocellular hypothalamic neurones into the primary capillary plexus within median eminence → Entering into the portal-hypophyseal pituitary circulation

GnRH stimulates the release of LH and FSH from gonadotrophs within the HPG. These hormones stimulate the ovaries and testes

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33
Q

What hormone is needed to maintain the corpus luteum?

A

hCG - human chorionic gonadotrophin

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34
Q

How does hCG provide support for pregnancy?

A

hCG maintains progesterone levels, which acts to maintain the endometrium lining, providing support for pregnancy

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35
Q

How many years after thelarche does menarche occur

A

2.3 years

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36
Q

What is meany by precocious puberty?

A

Early puberty (<8 years)

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37
Q

What is meant by primary amenorrhoea?

A

When you never had a period before

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38
Q

What is meant by secondary amenorrhoea?

A

When you start menses but stop for 3-6 months

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39
Q

What is the most common cause of secondary amenorrhea in women?

A

Pregnancy

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40
Q

Is precocious puberty more common in males or females?

A

Females

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41
Q

What is meant by delayed puberty?

A

When puberty starts after 14 years of age

42
Q

Is delayed puberty more common in males of females?

A

Males

43
Q

What is oligo-menorrhoea?

A

Irregular or infrequent periods >35 day cycle OR 4-9 cycles in total per year.

44
Q

What is used as evidence of ovulation?

A

Mid-luteal D21 Progesterone

45
Q

What happens in pregnancy that is different to a normal Menstrual cycle?

A

Beta hCG secretion → Activates FSH and LH receptors → Continues to support the corpus luteum → Secretion of progesterone

46
Q

Outline the Menstrual cycle

A
  1. FSH rises
  2. 2-3 follicle are stimulated
  3. Makes E2 (oestradiol) and inhibin B
  4. These reduce FSH
  5. Therefore, those follicles which are highly FSH dependant die, and the dominant grafian follicle which is less reliant on FSH emerges
  6. E2 levels continue to rise, which causes a switch from negative feedback to positive feedback, leading to an LH surge
  7. Causes ovulation - egg released from follicle
47
Q

What causes the swap from negative feedback to positive feedback during the follicular phase of the menstrual cycle?

A

High Oestradiol levels (E2) - causes a surge in LH levels

48
Q

How does the corpus luteum form?

A

the remainder of the follicle after ovulation has occured forms the corpus luteum

49
Q

What hormone is needed for the development of the Corpus Luteum?

A

LH

50
Q

What hormone does the Corpus Luteum secrete?

A

Progesterone

51
Q

if implantation does not occur, how does the corpus luteum degrade?

A

absent HCG stimulation → Shedding of endometrium lining → Menstrual cycle restarts

52
Q

What is meant by atresia?

A

When the FSH dependant follicles die

53
Q

Why is it essential thet GnRH is pulsatile?

A

Otherwise the receptors would become less sensitive

54
Q

Why is the pulsatility of GnRH higher during the follicular phase of pregnancy, compared with the luteal phase?

A

Progesterone which is secreted during the luteal phase negatively inhibits GnRH

55
Q

What can be used as a surrogate marker for GnRH levels?

A

Serum LH

56
Q

Why can GnRH levels not be measured directly?

A

GnRH is only released into local circulation; the hypo-physeal portal system

57
Q

What is primary hypogonadism?

A

When you have low E2/Testosterone due to a problem with the hormone-secreting gland eg testes of ovaries

58
Q

What is secondary hypogonadism?

A

When you have low E2/testosterone due to a problem with the hypothalamus or pituitary gland

59
Q

What is secondary hypogonadism sometimes referred to as?

A

Hypogonadotrophic Hypogonadism

60
Q

What happens to LH and FSH levels during primary hypogonadism?

A

They are high due to no negative feedback as the ovaries and testes are not producing E2/testosterone

61
Q

what can cause primary hypogonadism in males?

A

Infection, trauma and cancer of the testes

62
Q

What is the most common cause of primary hypogonadism in women?

A

Menopause - ovaries stop producging E2/inhibin, meaning FSH is higher

63
Q

A rise in which hormone can cause secondary hypogonadism?

A

Prolactin

64
Q

What happens to FSH/L levels during secondary hypogonadism?

A

They are normal / low

65
Q

What does LH stimulate the secretion of?

A

Sex steroids

66
Q

What are the symptoms of Menopause

A

Skin dryness/Hair thinning

Hot flushes/Sweating/sleep disturbance

Mood disturbance

Osteoporosis

Sexual dysfunction

Weight gain

Amenorrhoea

Cessation of fertility

Climacteric - Irregular periods in years close to Menopause

67
Q

What is menopause hormone therapy?

A

When oestrogen is given to the patient to stimulate the endometrium to grow

68
Q

What is added to the treatment of menopause if the endometrium is still intact?

A

Progesterone - prevents the risk of endometrial hyperplasia (increased thickness) or cancer

69
Q

Why does menopause result in osteoporosis?

A

Decreased bone mineral density as E2 stimulates osteoblasts

70
Q

When is gametogenesis initiated in males?

A

Puberty (gonadarche) → spermatogonia undergo differentiation and self-renewal

71
Q

How many mature sperm are produced per second?

A

1500

72
Q

Outline the lifespan of the an oocyte from before birth till puberty

A

Multiplication of Oogonia to ~ 6 million/ovary which form primary oocytes in the ovarian (primordial) follicles → Halted in prophase I

Proportion of primordial follicles undergo atresia → 2 million/ovary → 0.5 million/ovary at puberty

73
Q

Which cells secrete anti-mullerian hormone?

A

Granulosa cells in the ovaries

74
Q

What is AMH?

A

Anti-Mullerian Hormone

75
Q

What is AMH used for?

A

An Ovarian reserve marker - shows you how many eggs a patient may have left

76
Q

What is meant by premature ovarian insufficiency?

A

Early menopause

77
Q

how do you diagnose Premature Ovarian Insufficiency?

A

High FSH levels - two tests, done at least 4 weeks apart

78
Q

What happens to AMH levels at menopause?

A

The are very low

79
Q

What are the causes of Premature Ovarian Insufficiency?

A

Autoimmune causes eg Graves Disease
Genetic Influences
Cancer Therapy - radiotherapy / cancer treatment in the past

80
Q

What is the “male menopause” sometimes called?

A

Andropause

81
Q

What occurs in andropause?

A

Decrease in sexual satisfaction or a decline in a feeling of general wellbeing with low levels of testosterone in older men

82
Q

Roughly how much testosterone is ‘free’?

A

2% of testosterone

83
Q

What is most of the testosterone bound to?

A

Sex-Hormone Binding Globin (SHBG)

84
Q

Why is some testosterone still bioavailable?

A

38% is bound to Albumin weakly

85
Q

Why is there a male menopause?

A

Total testosterone is unchanged but SHBG is increased, meaning there is less “free” / bioavailable testosterone

86
Q

Why do morning erections occur?

A

testosterone release is diurnal, meaning it is higher in the morning and decreases thorughout the day

87
Q

What can reduce testosterone levels?

A

Glucose

88
Q

Why must testosterone be measured before 11am and when the patient is fasting?

A

Glucose levels can reduce testosterone levels

89
Q

What are the symptoms of testosterone deficiency?

A

Sexual dysfunction - Reduced libido

Erectile dysfunctions > Loss of early morning erections

Hair growth - Frequency of shaving?

Energy levels - General wellbeing, Fatigue

Mood disturbance

Body composition changes - Increased fat + reduced muscle mass

Gynaecomastia (breast enlargement in men)

Spermatogenesis - High levels of intertesticular testosterone needed

Bone health - Testosterone sometimes converted to oestrogen when present; lack thereof can lead to osteoporosis

90
Q

What enzyme converts testosterone to oestrogen?

A

Aromatase enzyme

91
Q

Where can aromatase enzyme be found?

A

Adipose
Adrenal Glands
Ovaries (Granulosa)
testes (Sertoli)
Brain
Bone
Skin

92
Q

What does aromatase convert Androstenedione into?

A

Oestrone

93
Q

What does aromatase convert Testosterone into?

A

17B-Oestradiol

94
Q

What factors cause increased activity of aromatase?

A

Age

Obesity

Insulin

Gonadotrophins

Alcohol

95
Q

What inhibits aromatase?

A

Tamoxifen
Anostrazole
(Treats Breast Cancer)

96
Q

What can aromatase inhibitors such as anostrazole be used to treat?

A

Breast Cancer

97
Q

Where can you find the enzyme 5-alpha-reductase?

A

Testes (seminal vesicle, epididymis)

Prostate

Turning Skin to Scalp

Liver

98
Q

What does 5-alpha-reductase do

A

Converts Testosterone into Di-Hydro-Testosterone

99
Q

What is the difference between testosterone and dihydrotestosterone (DHT)?

A

Dihydrotestosterone is a more potent ligand for the androgen receptor

100
Q

What does DHT have a role in?

A

DHT has a role in pubic and facial hair growth, prostate and male pattern baldness

101
Q

What can 5-alpha-reductase inhibitors such as finasteride be used to treat?

A

Prostate cancer

102
Q

What inhibits 5-alpha-reductase?

A

Finasteride

BRS ENDOCRINOLOGY (20 decks)

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