puberty & HPG

Question 1

define puberty

Answer 1

A stage of human development when sexual maturation and growth are completed and result in ability to reproduce

Question 2

what determines onset of puberty?

Answer 2

Switching on the HPG axis via hormones!

Question 3

at what stage is the reproductive system active?

Answer 3

at puberty

Question 4

what things occur during puberty

Answer 4

–Maturation of primary sexual characteristics (gonads and genitals)

– Appearance of secondary sexual characteristics (pubic and axillary hair, female breast development, male voice changes,…)

– Menstruation and spermatogenesis begin

Question 5

environmental influences in puberty?

Answer 5

pineal tumors can influence puberty in humans!

Question 6

In girls, what is the weight set point for puberty, what happens if it falls below this?

Answer 6

critical weight 47 kg

falls below> puberty comes late

Question 7

why does weight effect puberty?

Answer 7

Body weight (Leptins may be involved in signalling )

Leptins tied to adipose tissue, they signal the presence of fat in the body!

they interact w/ the hypothalamus and effect the release of GnRH.

Question 8

what hormones do BOTH males and females have before puberty?

Answer 8

testosterone and estrogen,

levels stay fairly constant until puberty!

Question 9

Normal age of puberty in females? males?

Answer 9

9-13 yrs

10-14 years

Question 10

in males and femlaes, pubic hair growth is a response to which hormones?

Answer 10

TESTOSTERONE!

Question 11

although we females have testosterone, what keeps their levels lower in our body?

Answer 11

we have testosterone binding proteins!

TBP

Question 12

functions of aromatase enzmye?

what inhibits it?

Answer 12

enzyme found in fatty tissue,

converts testosterone into excess estrogen

ZINC

Question 13

functions of estrogen in the growth spurt phase?

Answer 13

• important in mainting bone mass
• closing the epiphyseal plate

Question 14

Appearance of secondary sexual characteristics – girls

Answer 14

• 9-13 years
– Breast bud (thelarche)

– Pubic hair growth (T)

• begins (adrenarche)
– Growth spurt
– Onset of menstrual

• cycles (menarche) –

Pubic hair adult –

Breasts adul

Question 15

Appearance of secondary sexual characteristics -boys (testosterone anabolic androgenic steroid

Question 16

how can we access kids thats r goign through puberty?

and acess what stage theyre in?

Answer 16

TANNER SCALE

Question 17

Genital development in boys depends on?

Answer 17

testosterone

Question 18

the growth spurt is later in males or females?

Answer 18

later in boys!

Question 19

why does somatic growth end earlier in women?

Answer 19

cuz of estrogen>>closes epiphyseal plates earlier

Question 20

Somatic (body) growth, what does it depend on?

diff btw boys and girls

at what age ta8reeeban do girls stop growing?

Answer 20

boys r later, but rapid, and plates r slower to close!

girls>>16

boys>>18, 19

thats why guys faj2a y6ooloon!

Question 21

describe girl/ boy growth pattern from 8-18 yrs

how does it end? in who does it end firsT?

Answer 21

Earlier and shorter in women

Ended in both sexes by epiphyseal fusion

Oestrogen>> closes epiphyses earlier in girls

Question 22

Normal Pubertal development

Answer 22

Question 23

just for extra: why do men get acne?

Answer 23

testosterone causes increased secretion of the body’s sebaceous glands, escpecially those on the face!

Question 24

what is responsible for switching this axis on?!

Answer 24

GnRH

Question 25

what gene codes for the GnRH? what happens if this is blocked?

Answer 25

**GnRH -1 gene** ## Footnote Lack of gonadotrophin synthesis and secretion and reproductive development occurs if GnRH is blocked

Question 26

how can we treat prepubertal primates?

Answer 26

by giving GnRH gradually

Question 27

what r the characterisitcs of the hypothalamic releasing hormones?

Answer 27

Question 28

describe the HPG axis

Question 29

what structure in the anterioir pituitary makes LH & FSH?

Answer 29

Gonadotrophs which r cells

Question 30

what role does leptin and photoperoid have on the HPG axis?

Answer 30

they interact w/ the hypothalamus and effect the release of GnRH.

Question 31

funcitons of lepitin pattern of release?

Answer 31

Signals information about energy stores to CNS pulsatile!\> associated with variation in LH *Leptin can regulate GnRH levels, and its secretion may, in turn, be influenced by gonadal steroids but appears to be independent of LH control*

Question 32

GnRH path in activating the HPG timing of release? intensity of release affected by? its path from hypothalamus to pituitary

Answer 32

**its is pulsatile** **Every 1-3 hrs** Intensity of GnRH stimulus is affected by * Frequency of release * Intensity of release GnRh neurons at the median eminence in hypothalamus secrete it \> hypophyseal portal sys \> anterior pit\> bind to gonadotropes\> FSH & LH secreted

Question 33

what **time** of the day does the intital pulsitility of LH happen in males?

Answer 33

switches on in **sleep** ***pic just showing that pulsitility of LH mimics GnRH*** ***(LH is GNrH's puppy)***

Question 34

Precocious puberty?

Answer 34

development of puberty at an **EARLIER AGE** ## Footnote *maybe due to pineal tumor*

Question 35

name other axis's of the hypothalamic-pituitary

Answer 35

– Thyroid (hypothalamic–pituitary–thyroid axis HPT) – Adrenal (hypothalamic–pituitary–adrenal axis HPA) – reproductive glands (hypothalamic–pituitary–gonadal axis HPG)

Question 36

HPG axis in the Male

Answer 36

**L**H stimulates **L**eydig cells in testis *(diggin at the _surface_)* *the past their digging test lol\>\> and realeased **TESTosterone*** F**S**H stimulates **s**ertoli cells to release ABP, which keeps the concenctrstion of testosterone in spermatogenic cells high\>stimulates spermatogenesis. ***leydig cells r completely independent of the seminerfrous tubules, but the Seminefrous tubules, need the leydig cells to produce testosterone.*** ***add ur pic alaa***

Question 37

testosterone peaks?

Answer 37

**EARLY MORNING** every morning is a new "TEST" for us

Question 38

describe the strucutre of the Seminiferous Tubule cells

Answer 38

btw sertoli cells, theres tight junctions bc it provides the testes blood barrier! prevents bits of sperm from entering our BS! this could causes an atuoimmune response from the bits of sperms floating around chilling in our blood stream!

Question 39

function of Inhibin

Answer 39

secreted by Sertoli, checking levels of spermatogenesis ex: when sperms is so much, it send negative feedback to anterior p. to inhibit release of FSH * otherwise ur testes will explode with sperms*

Question 40

HPG axis in the females which cells respond to FSH? LH?

Answer 40

Granulo**s**a cells respond to F**S**H T**h**eca cells respond to L**H** *granny likes fish*

Question 41

Explain the potential effect that precocious puberty can have on adult stature

Answer 41

Short final stature as precocious puberty can cause rapid skeletal maturation which can cause linear bone growth to cease too early Growth spurt begins and ends earlier and therefore epiphyses close earlier / shorter final stature.

Question 42

Why might precocious puberty be stimulated by intracranial pathology such as meningitis?