1a Sex Hormones Flashcards
What are the four hallmarks of puberty?
- Development of secondary Sexual Characteristics
- Maturation of Reproduction Organs
- Obtaining ability to reproduce
- Production of sex-steroid hormones
What are the two main sex steroid hormone?
Oestradiol and Testosterone
What is meant by thelarche?
The onset of breast development
When is meant by menarche?
The onset of menstruation
What is meant by Pubarche?
The onset of pubic hair development
what scale is used to meant Breast development in femals?
tanner scale
What is gonadarche?
The onset of the activation of the gonads by the HPG axis
What is meant by spermarche?
The onset of spermatogenesis
When does adrenarche occur?
Starts around 2 years before gonadarche
What is adrenarche?
onset of adrenal androgen production
What is the first sign of puberty in males?
Increases in testicular volume
What is the first sign of puberty in women?
Thelarche
What is often used to see what the testicular volume should be at each stage of life?
Prader- Orchidometer
What hormone leads to the development of secondary sexual characteristics in females?
Oestradiol
What are the secondary sexual characteristics in females?
Breast Development
Hair growth (pubic and axillary)
Changes to sweat gland composition (skin becomes more oily and acne develops)
Changes to external genitalia
What hormone results in the development of secondary sexual characteristics in males?
testosterone
What are the secondary sexual characteristics of boys?
Increase in testicular volume
Pubic then Facial and Axillary hair development
Voice deepening
At what age does adrenarche occur in females?
6-9 Years Old
At what age does adrenarche occur in men?
7-10 years
What is the late sign of puberty in girls?
Menarche
At what age does puberty typically occur at in females and males?
Females - 8-13 Years
Male - 9-14 Years
What is an adult testicular volume?
> 15mLs
What is the average early pre-pubertal testicular volume?
Less than 4mLs
What are the adrenal androgens?
DHEA
DHEAs
Testosterone
How do the levels of FSH and LH change as girls and boys progress through the Tanner stages of development?
The serum levels of FSH and LH Increase
What is GnRH?
Gonadotrophin Releasing Hormone
What term is used to describe th secretion of GnRH?
Pulsatile - comes in waves
Why must GnRH secretion be pulsatile?
The continuous pulsatile administration of GnRH causes decreased LH/FSH secretion
What changes occur during mini-puberty?
Testicular descent out the stomach
Penile length increases
Sertoli cell maturation
When does the HPG axis undergo quiescence?
During childhood, before the onset of puberty
During puberty, what happens to the GnRH pulsatility?
There is increased nocturnal GnRH pulsatility
Describe how the HPG axis works?
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
What hormone is needed to maintain the corpus luteum?
hCG - human chorionic gonadotrophin
How does hCG provide support for pregnancy?
hCG maintains progesterone levels, which acts to maintain the endometrium lining, providing support for pregnancy
How many years after thelarche does menarche occur
2.3 years
What is meany by precocious puberty?
Early puberty (<8 years)
What i meant by primary amenhorrhoea?
When you never had a period before
What is meant by secondary amenorrhoea?
When you start menses but stop for 3-6 months
What is the most common cause of secondary amenorrhea in women?
Pregnancy`
Is precocious puberty more common in males or females?
Females