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Endocrinology > Gonads 2 > Flashcards

Gonads 2 Flashcards

1
Q

What is the difference between primary and secondary amenorrhoea?

A

Primary - never had a period

Secondary - used to have period but then they stopped

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2
Q

Which cells in the testes have receptors for FSH and LH?

A

Sertoli Cells - FSH Leydig Cells - LH

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3
Q

What are the effects of androgens in adults?

A

spermatogenesis growth and development protein and bone anabolism ie muscle/bone growth male sexual behaviour growth spurt

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4
Q

What’s the main progestogen?

A

progesterone

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5
Q
A
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6
Q

How are some of the androgenic effects mediated?

A

conversion to oestrogen

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7
Q

Name the weak androgen that is produced both in the adrenal glands and in the testes.

A

Androstenedione

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8
Q

What is the main oestrogen in pregnancy?

A

Oestriol

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9
Q

How is testosterone and DHT transported in the blood?

A

Mainly bound to sex hormone binding globulin (SHBG) Some of it is bound to albumin A small amount is free and bioactive This is in dynamic equilibrium

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10
Q

If fertilisation occurs, high levels of oestrogen and progesterone is needed. What molecule is produced to mimic LH and stimulate further oestrogen and progesterone production?

A

Human Chorionic Gonadotrophin

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11
Q

Complete sentence…

Rising oestrogen levels has a negative feedback effect on…

A

FSH

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12
Q

Most developing follicles will then undergo atresia and only one follicle remains, the Graffian follicle. What enables this follicle to survive the negative feedback on FSH?

A

The Graffian follicle is no longer FSH-dependent and can survive with it’s own local production of oestrogen. The other cells are FSH-dependent and so undergo atresia when the FSH is removed.

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13
Q

How do these pathways cause negative feedback?

A

Decreases the AMPLITUDE of the GnRH pulses.

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14
Q

Where does the aromatisation of testosterone into oestrogens occur?

A

adrenals, testes, liver, skin and brain

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15
Q

Describe the local positive feedback loop in the ovaries.

A

FSH stimulate aromatase and increase conversion of androgens to 17 beta oestradiol. Oestrogen then leaves the granulosa cell and binds to oestrogen receptors on the SAME granulosa cell and further stimulates production of oestrogen.

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16
Q

What hypothalamic hormone stimulates FSH and LH release from the pituitary gland?

A

Gonadotrophin Releasing Hormone (GnRH)

17
Q

Define progestogen.

A

Any molecule that induces secretory changes in the endometrium

18
Q

Define infertility.

A

Woman - inability to get pregnant

Man - inability to impregnate

may be due to excess prolactin (due to prolactinoma)

19
Q

What are the actions of progestogens?

A

Stimulates secretory activity in the endometrium and cervix Decrease renal NaCl absorption Growth of alveolar system in breast Increase in body temperature Negative feedback reg. on Hypothalamic GnRH

20
Q

Describe spermatogenesis in testes

A

Sertoli cells

Stimulated by FSH, limited by inhibin -ve feedback(direct /indirect)

Sperm maturation also NEEDS testosterone

21
Q

If fertilisation does not occur, what happens?

A

Oestradiol, Progesterone and Inhibin have negative feedback effect on FSH and LH leading to luteolysis and menstruation.

22
Q

Define oestrogen.

A

Any molecule that induces mitosis in the endometrium.

23
Q

What are the actions of oestrogens?

A

Stimulate mitosis in the endometrium Causes LH surge resulting in ovulation Feedback regulation of GnRH Stimulates osteoblasts Behavioural effects Metabolic actions (eg lipids) Increased salt and water reabsorption Increase HDL Stimulates growth of ductile system in the breast Decreases sebaceous gland secretion

24
Q

Describe the negative feedback from the testes to hypothalamo-pituitary axis.

A

Sertoli Cells - produce INHIBIN - negative feedback effect on hypothalamus and pituitary Leydig Cells - produce TESTOSTERONE - negative feedback effect on hypothalamus and pituitary

25
Q

Where does the reduction of testosterone into dihydrotestosterone occur?

A

prostate, testes, seminal vesicles, skin, adenohypophysis and brain

26
Q

What is the main oestrogen in the menstrual cycle?

A

17 beta oestradiol

27
Q

Describe androgen production

A

leydig cells

reduced by testosterone, -ve feedback reduce LH and GnRH

28
Q

What conditions must be in place for the rising oestrogen concentration switch from negative feedback to positive feedback on gonadotrophins(which causes surge in LH)?

A

Absence of progesterone

Oestrogen concentration must be high enough for a minimum of 36 hours

29
Q

What are the effects of androgens in the foetus and in adults?

A

Development of male internal and external genitalia foetal growth

30
Q

How is testosterone and DHT transported in the seminiferous tubules?

A

Bound to androgen binding globulin (ABG)

31
Q

What two reactions can testosterone follow and what do they produce?

A

Testosterone —> Oestrogen (aromatisation - by the action of aromatase) Testosterone —> Dihydrotestosterone (reduction) Dihydrotestosterone is a more potent androgen that binds to the same androgen receptors as testosterone.

32
Q

Draw a diagram showing the hypothalamo-pituitary-ovarian axis

A

Same as hypothalamo-pituitary-testicular but with ovaries

33
Q

What is oligomenorrhoea?

A

infrequent menstrual cycles, may be due to absence of LH surge ( eg due to insignificant oestrogenic effect at the end of follicular phase)

34
Q

Define amenorrhoea and differentiate between primary and secondary

A

Absence of menstrual cycles

Primary - Menstrual cycles NEVER happened to begin with

Secondary - Menstrual cycles did occur but have stooped

35
Q

The oestrogen levels in the luteal phase are as high as the levels that triggered ovulation in the follicular phase so why is there no LH surge in the luteal phase?

A

Presence of progesterone

Endocrinology (15 decks)

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