Puberty and the HPG axis Flashcards

1
Q

what is precocious puberty

A

puberty before the age of 8

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2
Q

why might precocious puberty be stimulated by meningitis

A

as menignitis infers with the pulsating release of GnRH, disrupting the axis

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3
Q

will individuals who have had precocious puberty be taller or shorter and why

A

shorter - as their epiphyseal growth plates will close sooner

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4
Q

what scale is used to asses points of puberty

A

tanner scale

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5
Q

define puberty

A

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

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6
Q

the secretion of what hormone from the pineal gland assists in puberty

A

melatonin

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7
Q

what role does leptin play in puberty

A

leptin determines when the child (particularly girls) have enough adipose tissue to sustain reproductive life

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8
Q

what is the critical weight for girls to enter puberty

A

47kg

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9
Q

what can cause precocious puberty

A

Brain injury, hydrocephalus, meningitis, congenital adrenal hyperplasia, pituitary tumour, pineal tumour

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10
Q

when does puberty begin in girls

A

9-13

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11
Q

what is aromatase

A

an enzyme which converts testosterone into oestrogen

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12
Q

what causes the closure of epiphyseal growth plates

A

oestrogen

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13
Q

when does puberty start in boys

A

10-14

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14
Q

what does HPG stand for

A

hypothalamo-pituitary-gonadal axis

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15
Q

what hormone is released from the hypothalamus in the HPG axis

A

GnRH

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16
Q

what does GnRG stand for

A

gonadotrophin releasing hormone

17
Q

what causes the release of GnRH

A

leptin and photoperiod

18
Q

in what pattern type if GnRH secreted

A

pulsatile pattern

19
Q

where does GnRH go

A

to the anterior pituitary gland to stimulate the release of hormones

20
Q

what hormones are released in response to GnRH

A

luteinising hormone and follicle stimulating hormone

21
Q

how is the HPG axis controlled

A

though positive and negative feedback

22
Q

when do LH secretions increases

A

during sleep

23
Q

in males what does LH do

A

stimulates leading cells to produce testosterone

24
Q

in males what does FSH do

A

stimulates Sertoli cells to help mature sperm cells and release inhibin

25
what does inhibin do
causes a negative feedback loop to FSH
26
why dos Sertoli cells have tight junctions
to prevent sperm from entering the blood stream as they have different antigens so are seen as foreign
27
in females where does LH go
goes to the theca interna cells
28
in females where does FSH go
granulose cells
29
what negative feedback occurs in the female HPG axis
normal oestrogen levels give negative feedback to the hypothalamus inhibin gives negative feedback to FSH
30
what cells in females produce inhibin
granulose cells
31
describe the positive feedback occurring in the female HPG axis
high levels of oestrogen send positive feedback signals to the hypothalamus causing a LH surge