Gonadal Function

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1

hypothalamus, pituitary, and gonads

the three component glands of the reproductive system

2

releases gonadotropin releasing hormone

function of the hypothalamus in reproductive system

3

releases luteinizing hormone, follicle-stimulating hormone, and prolactin among others

pituitary function in reproductive system

4

ovaries and testes

gonads

5

production of sperm and reproductive steroid hormones

2 main functions of testes

6

2 degrees Celsius lower than core body temperature

optimal sperm production temperature

7

seminiferous tubules and interstitium

two units of the testes

8

germ cells and Sertoli cells

the two cell types that lead to sperm production

9

spermatogonia

stem cells that form sperm

10

haploid cells

transform to form mature sperm

11

gonadotrophs

pituitary cells that produce LH and FSH

12

luteinizing hormone

stimulates Leydig cells in interstitium; testosterone is produced

13

follicle-stimulating hormone

stimulates Sertoli cells to produce androgen-binding protein; promotes spermatogenesis

14

glycoproteins

shared alpha unit wiht TSH and hCG; beta subunit confers specificity

15

pregnanolone

rate limiting step in testosterone synthesis

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Acetate -> cholesterol -> pregnanolone -> 17-hydroxypregnanolone -> dehydroepiandrosterone (DHEA) -> androstenedione -> testosterone

testosterone production

17

sex hormone-binding globulin (SHBG)

binds 60% of testosterone

18

albumin

binds 38% of testosterone

19

biologically active free form

2% of testosterone

20

hypergonadotropic hypogonadism

decreased testosterone, increased FSH/LH, and impaired sperm production

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Klinefelter's syndrome

presence of an extra chromosome leading to hypergonadotropic hypogonadism, small testicles, and azoospermia

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47, XXY, 11

karyotype of Klinefelter's syndrome

23

testicular feminization syndrome

most severe form of androgen resistance syndrome; mutations in androgen receptor and impaired androgen actions in target tissues; development of female phenotype

24

hypogonadotropic hypogonadism

decreased testosterone and decreased or inappropriately normal FSH or LH levels

25

Kallmann's syndrome

manifests as hypogonadism during puberty; impaired GnRH secretion; x-linked recessive

26

hyperprolactinemia

drug induced or prolactin-producing tumor; impairment of FSH/LH pulses and amplitude due to disruption of GnRH pulsations

27

Type II diabetes

associated with hypogonadotropic hypogonadism in at least 25-50% of men; insulin action is impt for LH release, affected by insulin resistance

28

Figure 22.1

...

29

progesterone and estrogens

hormones produced by female reproductive system

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ovaries

develop if no Y chromosome; paired organs with dual functions; gamete production and steroid hormone production

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hormones from hypothalamus, pituitary, and ovaries

prepare the uterus for implantation of embryo; uterine lining shed in absence of implantation

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early follicular phase

increased FSH, low LH, estrogen, and progesterone; promotes maturation of the follicle and release of estradiol

33

late follicular phase

estradiol rises rapidly, FSH decreases

34

midcycle/ovulation

LH peaks, estradiol drops

35

luteal phase

LH and FSH decrease, progesterone and estradiol increase; ruptured follicle becomes corpus luteum; produces progesterone 3 days after ovulation; inhibits LH secretion; new follicle develops

36

regression

FSH increases, progesterone and estradiol decrease

37

menstruation

levels constant, FSH increases

38

inhibit FSH secretion

rising estradiol levels-negative feedback

39

promote LH secretion

rising estradiol levels-positive feedback

40

luteinizing hormone

surge in production in response to increasing estradiol; ruptures follicle leading to ovulation; peaks midcycle

41

progesterone

peaks 8-9 days after LH peak

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LH and FSH decrease

estradiol and progesterone increase

43

corpus luteum regression

affect of decreasing FSH

44

decreasing estradiol and progesterone

corpus luteum regression affect

45

estrogen

promotes breast, uterine, and vaginal development

46

progesterone

induces secretory activity of endometrial glands; readies endometrium for implantation

47

androgens (androstendione, testosterone, and DHT)

excess leads to hirsutism, loss of female characteristics, development of male secondary sexual features

48

inhibins A and B

inhibit FSH production

49

activin

enhances FSH secretion and induces steroidogenesis

50

estrogens

18 carbon atoms; develop and maintain female sex organs and secondary sex characteristics; regulate menstrual cycle and maintain pregnancy; bone growth; synthesized from androgens

51

estrodial, estriol, and estrone

3 types of estrogens

52

estradiol

most potent estrogen; secreted almost entirely by the ovaries; 2-3% free (active), 97% bound to SHBG; measured by direct immunoassay; monitors ovarian function

53

estriol

made by fetus and placenta; >90% of known estrogens of pregnancy; promotes uteroplacental blood flow; increases during pregnancy; monitors fetoplacental unit

54

estriol

surges in the last 4-6 weeks

55

estrone

estrogen that occurs after menopause

56

progesterone

21 carbon atoms; prepare uterus for implantation, maintain pregnancy, prepare breasts for lactation, and used by fetus to synthesize cortisol and sex steroid precursors

57

corpus luteum

source of progesterone in non-pregnant women

58

placenta

source of progesterone in pregnant women

59

adrenal cortex and tesets

minor sources for progesterone

60

cholesterol

progesterone synthesized from; precursor for androgens and estrogens

61

corticosteroid-binding globulin (CBG)

binds 90-98% of progesterone

62

prolactin

initiates and maintains lactation; develops breast tissue

63

pituitary gland

source of prolactin

64

pregnancy, nursing, strenuous exercise, and daytime (diurnal variation)

times prolactin is elevated

65

dopamine from the hypothalamus

control for prolactin

66

human chorionic gonadotropin (hCG)

produced by placenta; 2 subunits alpha and beta; maintains progesterone levels in first trimester and aids fetal development

67

...

normal hCG levels

68

...

multiple pregnancy hCG level

69

...

ectopic pregnancy hCG level

70

...

miscarriage hCG level

71

...

trophoblastic disease hCG level

72

amenorrhea

absence of menses

73

oligomenorrhea

infrequent or irregular menstrual bleeding

74

hypogonadotropic hypogonadism

deficiency of FSH and LH; can cause secondary amenorrhea

75

hypergonadotropic hypogonadism

ovarian failure with elevation of FSH concentrations

76

polycystic ovary syndrome

infertility, hirsutism, chronic anovulation, glucose intolerance, hyperlipidemia, dyslipidemia, and hypertension