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endocrinology > The gonads > Flashcards

The gonads Flashcards

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1
Q

What do the gonads develop as

A

testes and ovaries

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2
Q

what determines the sex

A

SRY gene on y chromosome makes male characteristics - no SRY gene=ovary develop

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3
Q

in males what cells are the gonads made of and what do they develop into

A

primordial germ cell - spermatogonia
supporting cells - sertoli cells
steroidogenic cells - leydig cells

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4
Q

what are the functions of the gonads

A

gametogenesis - produce gametes - pass on genes

production of steroid hormones - steroidogenesis - steroids important at all aspects of reproduction

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5
Q

male and female gametogenesis

A

spermatogenesis - mature spermatozoa

oogenesis - production of ripe ova

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6
Q

male and female steroidogenesis

A

androgens, small amount oestrogen and progesterone

oestrogen and progesterone, small amount of androgens

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7
Q

describe the activation of sperm cells

A

sperm derivied from stem cells
early in embryo cells proliferate - 6-7million
spermatogonia stay at this level through life
go into quiescence in childhood
spermatogenesis begins at puberty

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8
Q

describe activation of oogonia

A

gametogenesis early in embryo 6-7million
atresia
maximum level 24wks of pregnancy - no more cells produced
2million at birth
400000 puberty
at menopause ovary is depleted

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9
Q

describe the process of spermatogeneis

A

diploid germ cell - multiply and differentiate
spermatogonia - mitotic division at puberty with GnRH, gonadotrophins and testosterone release
(some remain spermatogonia)
diploid primary spermatocytes – meiotic division
secondary spermatocytes – second meiotic division
sermatids
spermatozoa

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10
Q

summarise the production of sperm

A

gametogenesis begins at puberty
pool of spermatogonia remain constantly available for future cycles
produce 200 million sperm daily

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11
Q

describe oogenesis

A

diploid oogenia – mitotic division early in embryogenesis
primary oocytes - have layer around cell, primordial follicle - remain in meiotic arrest in prophase 1 until menstruation
secondary oocytes + polar body – second meiotic division – fertilisation
ovum + polar body

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12
Q

how is a polar body formed

A

one daughter egg cell keep all resources

other is just membrane and chromosome so degrades

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13
Q

summarise the production of female gametes

A

limited number of oogenia

promordial follicles - atrasia

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14
Q

describe the testes

A

coiled seminiferous tubules - - spermatogenesis takes place
move in collecting duct to Rete testes
drained into vas efferentia
through very coiled epididymis, stored there - gain nutrints to mature and develop motility
through vas deferens (surrounded by smooth muscle) to urethra to be expelled

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15
Q

describe seminiferous tissue

A

under connective tissue
spermatogonia along basement membrane
sertoli cells connected at a tight junction - form a blood testes barrier - large molecues can’t enter
spermatogonia enter sertoli cell - network of cytoplasm where they can mature - released into tubule
leydig cells - enzymes for steroidogenesis

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16
Q

describe sertoli cells

A

form seminiferous tubules
synthesis FSH and androgen receptors
produce inhibin, and androgen binding protein as a response to FSH
associated with developing spermatocytes

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17
Q

describe leydig cells

A

lie outside seminiferous tubule
synthesis LH receptor
principle source of testicular androgens - mainly testosterone

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18
Q

connection between sertoli and leydig cells

A

without high conc of testosterone in leydig cells spermatogenesis won’t take place

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19
Q

describe the ovaries

A

follicles contain oocyte and at least 1 layer of cells
there are follicules undergoing atresia
graafian follicle - max size - ready for ovulation
granulosa and thecal cells surround ovum
remnants of last corpus luteum
follicular fluid can be large

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20
Q

steroidogenesis in gonads

A

make progesterones C21
androgens C19
Oestrogens C18

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21
Q

process to make dihydrotestosterone

A 
cholesterol 
pregnenolone 
progesterone 
17-OH progesterone 
androstenedione 
testosterone 
dihdrotestosterone
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22
Q

process to make oestrone

A 
cholesterol 
pregnenolone 
progesterone 
17-OH progesterone 
androstenedione 
oestone
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23
Q

process to make 17B oestradiol

A 
cholesterol 
pregnenolone 
progesterone 
17-OH progesterone 
androstenedione 
testosterone 
17B-oestrodiol
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24
Q

process to make aldosterone

A 
cholesterol 
pregnenolone 
progesterone 
deoxycorticosterone 
corticosterone 
aldosterone
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25
process to make cortisol
``` cholesterol pregnenolone progesterone 17-OH progesterone 11-deoxycortisol cortisol ```
26
summarise the menstrual cycle
28 days begin on first day of menstruation ovulation - important reproductive event
27
what does the menstrual cycle consist of
ovarian cycle | endometrial cycle
28
how are ovarian and endometrial cycle related
follicular phase make 17B-oestrodiol - stimulate proliferative phase in endometrial cycle - lining thicker, add oestrogen and progesterone receptor - stimulate for later stimulation from progsterone luteal phase in ovarian cycle - make progesterone - reduce proliferation and make oestrogen, increase secretory activity of endometrium - suitable for implantation
29
describe the ovarian cycle
pre-antral follicle (gonadotrophin independant) FSH to early antral follicle (antrum is fluid filled sac) bigger and produce oestrogen late antral follicle graafian follicule - mature follicle corpus luteum (granulosa cell proliferate, invaded by BV can make oestrogen and progesterone for 13-14 days
30
describe hormone production during the ovarian cycle
FSH activate aromatase in granulosa cells (only cell with FSH receptor) thecal cells have LH receptor androgen diffuse into granulosa cells synthesis of oestrogen process same in corpus luteum Thecal cells have an LH1 receptor - stimulate steroidogenesis
31
describe the endometrial cycle
proliferative phase: dominant oestrogen thin endometrium thickens, glands grow straight, enlarge coil to survface of endometrium have increased blood supply secretory phase: progesterone dominant and oestrogen. endometrium becomes secretory later is necrotic and sheds. glands - secrete glycogen and mucopolysaccharides, bv relax mucosa engorged with blood. blastocyst arrive in uterus - ideal for egg arrival
32
what happens to uterus if no fertilisation
oestrogen and progesterone decline BV constrict - ischemia - necrotic endometrium stimulate prostoglandins - stimulate underlying myometrium to contract - help shed tissue
33
what is testosterone converted to and where
Di-hydrotestosterone potent in prostate, testes (seminiferous tubules) seminal vesicles, skin, brain and adenohypophysis, gives male phenotype, oil production and baldness this is reduction. 17B-oestradiol in adrenals, testes (Sertoli cells) liver, skin, brain. aromatisation - fats, in obesity causes moobs
34
describe the transport of testosterone
in blood 60% bound to sex hormone binding globulin (SHBG) 38% to albumin only 2% bioactive in seminiferous fluid bound to ABG
35
action of androgen in foetus
needed to make male genitalia and descend from the abdomen | mother's HCG stimulate production of testosterone in utero testosterone needed, with other hormones for foetal growth
36
action of androgens in adults
spermatogenesis takes 4 months? maturation requires high testosterone growth and development male genitalia and secondary sex characteristics muscle and bone growth - lack=osteoporosis male sex behaviour pubertal growth spurt some androgenic effects mediated by conversion to oestrogen in the brain
37
what is oestrogen
any substance (natural/synthetic) that induces mitosis in endometrium
38
main oestrogen
17B-oestrodiol
39
reproductive action of oestrogen
``` stimulate proliferation of endometrium trigger LH surge in ovulation vagina secretions in breast stimulate growth of ductile system decreases sebaceous gland secretion ```
40
non-reproductive effects of oestrogen
-ve and +ve feedback for GnRH stimulates osteoblasts - so don't get osteoporosis metabolism of lipid - female less chance of CVD sexual arousal fluctuates water in menstrual cycle
41
progesterone definition
any substance inducing secretory change in endometrium
42
main progesterone
progesterone
43
main effect of progesterone
stimulates secretory activity in endometrium and cervix so fertilised egg can implant
44
what makes progesterone
corpus luteum
45
lesser effects of progesterone
increase body temp - see if ovulating growth of alveolar system in breast - long progesterone to prime breast competitive inhibition of aldosterone -ve feedback on hypothalamic GnRH
46
describe the hypothalamo-pituitary-testicular axis
Hypothalamic pulse generator GnRH released from hypothalamus in fluctuation every 1 1/2 to 2 hours stimulate coincident pulses of FSH and LH release LH stimulates hormones (androgen production) - Leydig cells - testosterone FSH stimulates Sertoli cells (spermatogenesis) - inhibin inhibin and testosterone inhibit hypothalamus and anterior pituitary gland
47
describe the hypothalamo-pituitary ovarian axis
pulses of GnRH released every 1 1/2 - 2 hours stimulate LH and FSH ovary make oestrogen and progesterone -Ve feedback against GnRH and LH and FSH
48
what is GnRH
gonadotrophin releasing hormone
49
how long is the early follicular phase
1st 5 days after day 1 of bleeding
50
describe the early follicular phase
``` LH and FSH cause follicles to develop 5-10 eggs enlarge Graafian follicles develop grow under FSH regulation make oestradiol and little progesterone little oestrodiol so high LH and FSH - cause follicles to grow ```
51
describe the early mid follicular phase
oestradiol increases - follicular cells grow largest follicle grow and make more oestrogen -e feedback loop to LH and FSH get autocrine +ve feedback loop - more oestrogen=more granulosa cells
52
mid-follicular phase
now LH and FSH turn off because of rising oestradiol (E2) | kills all follicles except Graafian follicle - autonomous - make own oestrogen
53
describe the late follicular phase
Extremely high E2 causes +ve feedback on GnRH and LH secretion - pituitary activated by oestrogen - causes LH surge when E2 has reached threshold (10x higher than normal) 2 population of GnRH neurons +ve feedback require high level oestrogen to kick in cause follicle to open and egg release down follicular tube
54
describe the luteal phase
progesterone prepares the endometrium for implantation corpus luteum make progesterone in 2nd half of cycle/pregnancy - convert endometrium to secretory lining progesterone, oestradiol and inhibin -ve feedback on LH, FSH luteolysis, corpus luteal involutes - menstruation
55
what is amenorrhoea
absence of menstrual cells primary - if never had a period, born without GnRH secondary - women had periods and then stop
56
what is oligomenorrhoea
infrequent cycles, less severe than amenorrhoea,
57
definition of infertility
couple cannot get pregnant after 12 months of unprotected sex
58
causes of infertility
pituitary failure - tumour, pituitary removed, can't produce LH/FSH prolactinoma - make prolactin inhibit LH and FSH, men and women primitive and bad contraception azoospermia - no sperm Testicular failure: mumps - increasing because people not taking the vaccine. Klinefelter syndrome XXY Ovarian failure: turner's XO- short, wide spaced nipples, shield chest polycystic ovarian syndrome (PCOS) - more common than diabetes, too many eggs produced, infrequent periods, hyper-androgenaemia eg increased male pattern hair, acne polycystic ovaries - increased number of enlarging ovarian follicles
59
oestrogen and progesterone affect in luteal phase
inhibit LH and FSH (-ve feedback) | decreases when oestrogen and progesterone decrease
60
effect of 17-OH progesterone
at end of follicular phase | enhance oestrogen's positive feedback effect

endocrinology (12 decks)

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