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Reproduction > Session 4 - Puberty > Flashcards

Session 4 - Puberty Flashcards

1
Q

what are some important factors influencing the timing of puberty and trigger for reproductive life

A

the pineal gland - disorders of this cause early onset of puberty
body weight - low can stop mensturation
nutrition
leptin

LIGHT

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2
Q

what scale is used to assess the different stages of puberty in make and female

A

the tanner scale

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3
Q

what are primary sexual characteristics

A

external genitalia you are born with ( at birth )

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4
Q

what are secondary sexual characteristics

A

develop after puberty (pubic hair , breast enlargement) etc

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5
Q

when do girls usually start puberty

A

ages 9-13

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6
Q

describe the sequence of events in puberty for girls

A 
thelarche (brest bud development) 
pubic hair (due to testosterone) 
growth spurt (oestrogen level important in fusion of epiphyseal growth plates along with GH) 
menarche (start of menstrual cycle) 
pubic hair which become coarse 
breast development
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7
Q

when do boys usually start male development

A

10 - 14 yrs

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8
Q

describe the puberty stages in relation to male development

A 
genital development (testes)
pubic hair growth (testosterone) 
spermatogenesis 
growth spurt (later in boys, episodes plates slow to close due to lower level of oestrogen) 
genital enlargement 
pubic hair (course)
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9
Q

what is precocious puberty

A

early onset of puberty due to incr in oestrogen levels rising earlier than normal

result in short stature

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10
Q

describe the chemicals and features of somatic growth in both male and female

A

epiphyseal plate fusion occur via oestrogen in BOTH genders (androgens such as testoterone can convert to oestrogen

GH, IGF and sex steroids in both sexes also help

growth spurt occur longer in mean as oestrogen close episode plates in female quicker

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11
Q

what is the hormone that triggers the start of puberty

A

GnRH (gonatropin releasing hormone) produced in hypo

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12
Q

what is thought to stimulate GnRH from hypo

A

leptin

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13
Q

describe how GnRH is secreted and what gland it acts upon and what it releases

A

it is secreted in pulsatile secretions and acts upon the anterior pituitary (paracrine hormonal signalling) to secrete LH and FSJ from gonadotrophs in both female and male

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14
Q

when is GnRH secreted

A

nightime

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15
Q

describe the slow onset of puberty

A

GnRH secretion turn on in night time and brings out phenotypic changes such as breast buds and testes enlargement

onset associates with slow rise of LH and FSH

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16
Q

is precocious puberty normal

A

no but most parts of reproductive system can work before normal age of puberty just don’t because hormone levels are low due to low GnRH secretion

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17
Q

what do LH and FSH act upon and do

A

acts upon gonads and stimulate androgen and oestrogen release that change primary sexual characteristics into secondary ones

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18
Q

what specific cells do FSH and LH act upon in the male

A

FSH stim Sertoli cells to make sperm in semi tubules

LH stim ledig cells to produce testosterone

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19
Q

what specific cells do FSH and LH act upon in the female

A

granulosa cells respond to FSH

Theca cells respond to LH

20
Q

what happens when FSH stimulates gonadal ‘follicles’ (primary oocyte in female , sperm in male)

A

release inhibin which cause neg feedback on FSH only to prevent further gonadal advances

21
Q

list some environmental influences that could influence a new ‘puberty’

A

triggered by changes in day length
pineal gland
secretion of melatonin

22
Q

what is one type of tumour that can affect the timing of puberty

A

pineal

23
Q

what is GnRH - 1 and what is it used for

A

responsible for GnRH and expressed in specific cluster of neurones in hypo

has the ability to induce puberty

24
Q

what is 1 consequence of GnRH being blocked

A

gonadotropin synthesis, secretion etc is stopped

25
Q

what role is GnRH most important for

A

reproductive maturation

26
Q

what connects the hypothalamus to the anterior pituitary

A

superior hypophyseal artery

27
Q

does the AP secrete or produce hormones

A

produces (via glandular cells)

28
Q

what 3 hormones are most significant for reproduction from AP

A

prolactin
FSH
LH

29
Q

what affects the intensity of the GnRH stimulus

A

frequency of release and intensity of release

30
Q

how does GnRH travel to the pituitary

A

hypophyseal portal system

31
Q

describe the difference in LH and FSH abundance in a pre teen and teen

A

in pre teen would not have a lot of FSH and LH to intimate gonadal function but between age of 9-12 it becomes more pulsatile during the night initiating gonadal function and development

32
Q

what chemicals rise as male and females sleep

A

testosterone and LH which could account for early pubertal changes in males

females - oestrogen

33
Q

what affects testosterone secretion and how does it come about

A

LH stimulate leydig cells which produce testosterone from cholesterol

once production starts they remain constant

highest in the morning (circadian rhythm)
environmental stimuli

34
Q

describe the dependant relationship of seminiferous tubules and leydig cells

A

although they function independently ST need them for survival

35
Q

describe the histology of ST cells and the two main components

A

epithelium made of 2 cell types (supporting/Sertoli cells and spermatogenic/germ cells)

36
Q

what is the function of Sertoli cells

A

provide nutrition and hormonal support to germ cell to allow them to grow

37
Q

what are Sertoli cells sensitive to

A 
FSH levels (incr sperm production) 
secreted inhibin display neg feedback on AP FSH to maintain amount of gonadal function
38
Q

why is the blood testes barrier important

A

separates basal and luminal compartments to allow sperm production to develop aside from maturation in case any fragments get into ECM and trigger an immune response

tight jxns allow for communication

39
Q

describe how FSH and LH bring about a target response on ovaries

A

act via Ga adenylate cyclase

target ovarian granulosa cells, theca internal and stim sex hormone production (steroid genesis) and control gamete production

40
Q

describe the effects of oestrogen and progesterone on GnRH

A

female

  • moderate amount of oestrogen reduce GnRH secretion via neg feedback
  • a lot of oestrogen promote GnRH feedback via positive feedback and create LH surge and stim ovulation
41
Q

describe the effects of oestrogen and progesterone on FHS and LH

A

female

  • progesterone incr inhibitory effects of moderate oestrogen
  • prevent positive feedback of high oestrogen so no LH surge
  • oestrogen reduce GnRH per pulse
42
Q

describe the effects of inhibin on FSH and where its secreted from

A

from granulosa cells of corpus leteum

inhibits FSH (same in both genders)

small inhibitory effect on LH

43
Q

describe the processes GH goes through to initiate a growth spurt

A
  • secreted from pit
  • incr TSH
  • incr metabolic rate
  • promote tissue growth
  • incr androgens which retains minerals in body to support muscle and bone growth
  • growth spurt
44
Q

what does leptin help determine

A

if body fit enough to have baby

also signals info about energy stores to CNS

45
Q

what is the role of leptin

A

neuroendocrine fin

  • reproductive dysfunction associated with leptin def
  • leptin can access onset of reproductive fxn

can regulate GnRH levels

46
Q

how is leptin secreted

A

via pulsatile rhythms associated with variations in LH

secretion may be influenced by gonadal steroids but may be independent of LH controversy

Reproduction (3 decks)

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