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DEMS Unit 3 > Intro to Repro system > Flashcards

Intro to Repro system Flashcards

1
Q

3 major categories of sex steroids

A
  1. Progestins
  2. Androgens
  3. Estrogens
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2
Q

Extra-gonadal tissues that secrete various sex steroids

A
  1. Placenta
  2. Dermis
  3. Adrenal glands
  4. Adipose tissue
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3
Q

Which is a glucocorticoid and which is mineralocorticoid?
Cortisol
Aldosterone

A

Cortisol: Glucocorticoid

Aldosterone: mineralocorticoid

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4
Q

How many carbons in:

Cholesterol

A

Cholesterol: 27 C

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5
Q

Gonadal cells (Ie: Leydig cells) cans synthesize cholesterol via which 2 ways?

A
  1. De novo from co-enzyme A

2. Derive cholesterol form LDL in circulation

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6
Q

RLS in steroid synthesis involves which enzyme?

A

20, 22 desmolase (SCC Enzyme) in mitochondria
- this is the first step of converting Cholesterol (27C) to Pregnenolone (21C) in the mitochondria

*pregnenolone is then converted into all other sex steroids

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7
Q

Cholesterol is converted to ______ in the first step of steroid synthesis. ______ is then converted into all other sex steroids.

A

Pregnenolone (21C)

Pregnenolone (21C)

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8
Q

Progestins

  • how many carbons?
  • Which hormones?
  • Can be precursor for production of what?
A

(yellow box)
4 progestins - all 21 Cs

(1) Pregnenolone →
(2) 17a-Hydroxypregnenolone OR!!
(3) Progesterone → which can get converted to
(4) 17a-Hydroxyprogesterone

Can be precursor for aldosterone and cortisol by adrenal glands

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9
Q

How many carbons are in aldosterone and cortisol?

A

21Cs

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10
Q

What are the major circulating progestins in males and females?

A

Females: progesterone

Males:
17a-Hydroxyprogesterone

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11
Q

Good marker for late-onset congenital adrenal hyperplasia

A

17-hydroxy progesterone

discussed in other lecture

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12
Q

Progestins affect almost all tissues in the body, most notably which ones?

A
  • the exact same 3 as Estrogens:
  1. uterus
  2. ovaries
  3. breasts
  • growth and development of the tissues and organs related to ovulation, menses, pregnancy, and lactation.
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13
Q

How many carbons are in androgens? Where does it come from?

What are the major androgens that are synthesized in the human body?

A

19C

Derived from cholesterol via pregnenolone
(same as estrogen)

  1. testosterone
  2. dehydroepiandrosterone (DHEA)
  3. DHEA-S
  4. DHT
  5. Androstenedione

*note that estrogen is 18C

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14
Q

Where is the majority of testosterone produced in males?

A

Males:

  • 95%: Leydig cells in testes
  • 5%: adrenal cortex
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15
Q

Where is the majority of DHEA and DHEA-S produced?

A

Adrenal cortex

- excellent marker of adrenal androgen activity

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16
Q

What is the precursor for ovarian estradiol production by the GRANULOSA CELLS?

A

Androstenedione from the theca cells in the ovaries

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17
Q

Enzyme that converts Testosterone to DHT

A

5 a-Reductase
(mainly in testosterone target cells)

*DHT is 30-50x more active and cannot be converted to estrogens

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18
Q

Do androgens have significant effects on the growth of the reproductive system? What about testosterone?

A

Androgens No

Testosterone yes
- affects almost all tissues in the body

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19
Q

Difference between androgenic and anabolic effects of testosterone

A
  1. Androgenic:
    impacts growth and dev of internal and ext genitalia
    - dev of 2ndary sex char, spermatogenesis, sexual fantasy and libido
    - stuff you know
  2. Anabolic:
    Growth promoting effects on somatic tissues (BONE AND MUSCLE)
20
Q

What are the key feedback inhibitors for:

  1. Hypothalamic-Pituitary-ovarian axis
  2. Hypothalamic-Pituitary-testicular axis
A
  1. Progesterone and estradiol

2. Testosterone

21
Q

How many carbons are in Estrogen? What is it derived from?

A

18C

Cholesterol via pregnenolone
same as androgens
- 2 ex of estrogens: estrone, estradiol

22
Q

How are estrogens produced from pregnenolone? What enzyme is involved in that final conversion?

A 
Cholesterol →
Pregnenolone →
Progestins →
Androgens →
Estrogens (via aromatase)
23
Q

Estrogens:
E1
E2
E3

Names and which one is most potent

A

E1: estrone
E2: estradiol
E3: estriol

*one, two, three OH groups

E2 is most potent, E3 is least

24
Q

Where is estradiol produced in males and females

A

Males:
Seroli cells of testes

Females:
Granulosa cells of ovary

25
Q

Where is estrone (E1) and Estriol (E3) produced?

A

E1: adipose tissue
E3: important placental product

26
Q

Why is pulsatile secretion of GnRH the key to physiologic stimulation of the anterior pituitary?

A

Constant administration of GnRH actually suppresses the pituitary response

27
Q

When do FSH and LH reach their peaks?

A

Shortly before ovulation

28
Q

LH and FSH stimulate the production of which hormones?

Where do they work?

A

Sex steroids
- negative feedback control on hypothalamus and pituitary

Inhibit
- neg feedback control on pituitary

*at midcycle, estradiol also exerts pos feedback mech on pit gland → FSH + LH surge

29
Q

Two imp cells in testis + ovary

A

Testis:

  • Leydig
  • Sertoli

Ovary:

  • Theca
  • Granulosa
  • Male Leydig and female Theca are interstitial cells and are similar
  • Sertoli + granulosa cells are similar
30
Q

Things that Male Leydig and female Theca are interstitial cells and share

A
  • Able to make androgens + progesterone in presence of LH secretion/rcptrs
  • Unable to make estrogens due to absence/lack of aromatase
    (fxn of sertoli and granulosa cells)
31
Q

Things that Male Sertoli and female Granulosa cells have in common

A

Able to make inhibin in presence of FSH receptors

Able to convert androgens into estrogens due to presence of aromatase

32
Q

How does LH stimulate the rate limiting conversion of cholesterol into pregnenolone?

A
  1. Increasing the amt of desmolase

2. Enhancing the affinity of desmolase for cholesterol

33
Q

Spermatogenesis requires which hormones

A 
LH
FSH
Leydig cells
Sertoli cells
Testosterone
34
Q

Sertoli cells are organized into tubular epithelium known as ________. It is supported by the presence of _____ between sertoli cells.

A

Seminiferous tubules

Tight gap jxns

*seminiferous tubules are responsible for maturation of gametes

35
Q

Effects of FSH binding to Sertoli cells

A
  1. Increased production of androgen binding protein
  2. Enhanced conversion of testosterone (from Leydig cells) into estradiol
  3. Production of Inhibin

*sertoli cells are the primary source of inhibin in males

36
Q

The gametes and their surrounding granulosa cells are called ________. The _______ follicle matures each month.

A

Primordial follicles

Dominant follicle

37
Q

Oogenesis and ovulation require which hormones and cells?

A
  1. LH
  2. FSH
  3. Testosterone
  4. Estradiol
  5. Granulosa cells
  6. Theca cells
38
Q

Granulosa cells lack the enzyme which converts progesterone into androgens, well then how the hell do androgens get produced in females?

A

Progesterone from the granulosa cells diffused to the theca cells →
converted to androstenedione
→
theca cells lack aromatase →
androstenedione diffuses back to granulosa cells →
conversion to estradiol

39
Q

LH binds to which cells and FSH binds to which cells?

A

LH binds to Leydig Cells
- L → L

FSH binds to Sertoli cells
- S → S

40
Q

The biological activity of LH and ____ are very similar. So much so, that it is often substituted for LH because it is much more readily available.

A

hCG

*hCG can be used therapeutically to initiate spermatogenesis in azoospermic or oligospermic men

41
Q

FSH leads to the synthesis of _______, which is secreted into the luminal space of the seminiferous tubule, near the developing sperm cells. ________ Helps to keep local testosterone levels high.

A

Androgen Binding protein (ABP)

Androgen Binding protein (ABP)

42
Q

How is FSH involved in converting Testosterone into estradiol in men?

A

It causes the synthesis of Aromatase.

Testosterone diffuses from Leydig cells → Sertoli cells
- In Sertoli cells, aromatase converts T into Estradiol

43
Q

4 things that FSH stimulates Sertoli cells to synthesize

A
  1. Androgen binding proteins (ABP)
  2. Aromatase
  3. Growth factors
  4. Inhibins

*FSH may also increase the fertility potential of sperm!

44
Q

Which one inhibits LH, which one inhibits FSH:

Testosterone vs Inhibin

A

Testosterone inhibits pulsatile release of LH
- by inhibiting pulsatile release of GnRH

Inhibin inhibits FSH secretion
(FSH stimulates Sertoli cells to make inhibin, and inhibin “inhibits” FSH secretion)

45
Q

Two immediate precursors for Testosterone and two hormones that can come from Testosterone

A

Androstenedione or
Androstenediol
→
Testosterone

Testosterone →
Estradiol or DHT

46
Q

All of the DHEA in male plasma originates from where?

A

Adrenal glands

- Can test adrenal fxn using DHEA

DEMS Unit 3 (26 decks)

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