What age is average for menarche in females?
13yrs old<br></br><br></br>Usually no egg present (anovulatory)
What is a sign of male puberty?
First ejaculation (often nocturnal)<br></br><br></br>Usually only seminal plasma with no spermatozoa
Define gonadarche:
Changes dependent on steroid hormones from gonads
Define adrenarche:
Changes dependent on steroid hormones from adrenal gland
What age do girls hit peak growth velocity?<br></br>What age do boys hit peak growth velocity?
Girls = 12 yrs<br></br>Boys = 14yrs
What explains the height difference between men and women?
Boys are older and taller at point of take off.<br></br><br></br>Amount grown during growth sprout is actually the same in males and females
Complete the blank:<br></br><br></br>Adult men have _____ times more lean body mass than women.<br></br><br></br>Adult women have _____ times more body fat than men.
Adult men have 1.5 times more lean body mass than women.<br></br><br></br>Adult women have 2 times more body fat than men.
How long after menarche do females experience their first ovulation?
Ranges from months → 2 years
When is adult stature reached in females?
15
When is adult stature reached in males?
17
What do testicular androgens cause in males?
1) Development of genitalia<br></br>2) Body hair<br></br>3) Enlargement of larynx and laryngeal muscles
What do ovarian oestrogens cause in females?
Development of breast and genitalia
What do ovarian and adrenal androgens cause in females?
Pubic + auxillary hair
When do testes descend from abdomen?
7-8th month in utero
What hormones control descent of testes?
1) Mullerian inhibitory substance (MIS)<br></br>2) Testosterone
What directs the pull of testes?
Gubernaculum
When does spermatogenesis begin?
9 yrs
When is mature spermatozoa produced?
14-15yrs
How many ovaries are present at birth?
500,000
How many ovaries are present at puberty?
83,000
What are cryptorchid testes?<br></br><br></br>What is the treatment?
Testes that fail to descend at birth (3-4% of males)<br></br><br></br>0.8% fail to descend by 1 yr<br></br>0.3% fail to descend by 9yrs (commencement of spermatogenesis)<br></br><br></br>Treatment = surgery or Gonadotrophins/GnRH
How much cooler do the testes need to be compared to the body for spermatogenesis?
3.1 degrees
What are the daily patterns of hormone changes seen during puberty in females?
1) Fluctuations<br></br>2) ↑ amplitude (at night then always)
How often do hormonal pulses need to be for puberty to occur?
1-3 hours
What is the first endocrine change to occur in puberty?
<b>Dehydroepianosterone</b>
Where are the following released from in females?<br></br>Oestradiol<br></br>Oestrone<br></br>Androgens
Oestradiol: follicles in ovary<br></br>Oestrone: body fat<br></br>Androgens: adrenal gland
What is the source of oestrogens in males?
Steroli cells
What causes acne?
Androgens → ↑ sebum → clogged glands → acne
What is the effect of growth hormone during puberty?
1) Increases bone and tissue growth (along with androgens)<br></br>2) Roles in protein synthesis and glucose homeostasis
What is the effect of thyroid hormone during puberty?
↑ metabolic rate
What is onset of puberty associated with
<b>GnRH pulsing</b><br></br><br></br>(other components of system = <b>Neurokinin B</b> + <b>Kisspeptin</b>)
What weight does puberty start for girls?
47Kg
What weight does puberty start for boys?
55Kg
What hormone may play a role in explaining the nutritional cause for pubertal increase in GnRH?
Leptin
What is the effect of Melatonin and pineal secretions on puberty?
Inhibit reproductive function
Comment on blind/deaf childrens puberty age:
Usually earlier (?sensory deprivation → quicker puberty?)
Effect of pullutants on puberty?
Xenoestrogens (plastic industry) → earlier puberty<br></br><br></br>Other pullutants delay male puberty
Effect of climate/altitude?
↑ altitude → delayed puberty
Effect of genetics on puberty?
Black girls hit puberty before white girls