Session 3 Flashcards
When are Primary sexual characteristics established?
Before birth
How is the tissue composition different in a non lactating breast?
There is more specialised fat than mammary gland
Between what age is puberty in girls?
8-13
Between what age is puberty in boys?
9-14
What is the first step in female puberty?
Bread bud development (Thelarche)
What is Adrenarche?
Pubic hair growth
What is Menarche?
Onset of menstrual cycles
What is the sequence of puberty in girls?
Thelarche Adrenarche Growth spurt (Short) Menarche Pubic hair adult Breasts adult
What is the first step in male puberty?
Genitalia development begins
What is the sequence of puberty in males?
Genitalia development begins Adenarche Spermatogenesis begins Growth spurt (Longer) Genitalia adult Pubic hair adult
What ends the growth spurt in both sexes?
Epiphyseal fusion
Why doesn’t the reproductive system work before puberty?
Has the capacity to, but hormone levels are too low due to low levels of GnRH secretion from the Hypothalamus
What is the onset of puberty associated with?
Steady rise in FSH & LH secretion due to a rise in GnRH secretion
What does the level of pubic and axillary hair depend on?
Androgens in both sexes (Come from Adrenals in girls, Testosterone in boys)
What does breast development depend on?
Oestrogens
How can males develop breast tissue?
Testosterone can be converted to oestrogen causing some breast tissue to develop (Gynecomastea)
What is the growth spurt dependent on?
GH
Steroids
Oestrogen closes the epiphyses earlier in girls
What may be the cause of the timing of puberty?
A decreased sensitivity to the negative feedback by steroids
Maturation of central mechanisms within the brain
Pineal tumours
What is the average critical weight for Menarche?
47 kg
May be signalled to the hypothalamus via leptins
What does the Pineal gland secrete?
Melatonin (Due to changes in length of light, secreted when darkness)
What is Precocious puberty?
Signs of puberty before the age of 8
What are the causes of Precocious puberty?
Most unknown
Can be due to Pineal tumours
Can be due to Meningitis
Can be due to uncontrolled gonadotrophin or steroid secretion (Hormone secreting tumours)
How can Meningitis cause Precocious puberty?
Inflammation causes stimulation of the central maturation centre
What makes up the climacteric?
Pre menopause
Menopause
Post menopause
What are some of the characteristics of Pre menopause?
Typically from age 40 Changes in the menstrual cycle Follicular phase shortens so ovulation early or absent Less oestrogen secreted LH & FSH rise Reduced fertility
What are some of the characteristics of Menopause?
Cessation of menstrual cycles Average ago 49-50 No more follicles left to develop Oestrogen levels fall dramatically FSH & LH levels rise (Esepcially FSH) No inhibin
What are some of the effects of the Menopause?
Vascular changes - Hot flushes - due to falling levels of Oestrogen in the blood Regression of the endometrium Shrinking of the myometrium Thinning of the cervix Breast tissue reduction Vaginal rugae lost
What effect does the Menopause have on bone?
The density reduces as the protective mechanism of Oestrogen is lost. Risk of Osteoporosis increases
How can the symptoms of the menopause be relieved?
Hormone replacement therapy - Oestrogen can be given orally or topically
Should give progesterone in females with uterus as prevents an increased risk of cancer
How does the reproductive life of males end?
Insidious, no obvious event
Sperm production gradually declines until the system stops in late 70s/80s.
Testosterone levels drop
