Reproductive Hormones Flashcards
The Y chromosome secretes
SRY antigen
What does SRY antigen stimulate
Stimulates undifferentiated gonads to develop into testes
Testosterones role in male fetus
Stimulates Wolffian Duct to develop into epididymis, vas deferens, seminal vesicle
Sertoli cells of the testes release
MIH (Mullerian-inhibiting hormone)
What does MIH do in a male fetus?
Inhibits Mullerian duct from developing into female genitalia
In a male fetus, prostate tissue converts testosterone into?
DHT
What does DHT stimulate in a male fetus?
Stimulates development of scrotum, penis, and prostate gland
What happens if SRY antigen is not present?
The undifferentiated gonad develops into ovaries
No MIH or testosterone is produced
If testosterone is not present what happens in the female fetus?
Wolffian duct will not develop
If MIH is not released what happens to the Mullerian duct?
Develops into fallopian tubes, uterus, and vagina
Function of the testes
Primary male sex organs
Production of sperm
Production of testosterone
What two hormones are needed from spermatogenesis?
FSH and testosterone
Where is testosterone synthesized?
Interstitial Cells of Leydig
What are the anabolic effects of testosterone?
Spermatogenesis
Bone and muscle growth
What are the androgenic effects of testosterone?
Development and maintenance of male accessory sex organs
Differentiation of male reproductive tract
Development of secondary sex characteristics
Libido, potency
What happens to testosterone in males are they age? How is this different than estrogen in women?
Slow, constant loss of testosterone over lifespan
Women have significant loss of estrogen after menopause and then it becomes a slow, constant loss
What is the signaling pathway to testosterone’s release?
Hypothalamus releases GnRH
GnRH stimulates anterior pituitary to release FSH and LH
LH stimulates testosterone synthesis and secretion from Leydig cells
FSH stimulates ______________ via the __________ cells of the testes
Spermatogenesis
Sertoli Cells
Sertoli cells release _________ which inhibits ________
Inhibin
FSH
At puberty, the hypothalamus increases/decreases GnHR release
Increases
Increase of GnHR release at puberty causes?
Anterior pituitary gland to release more FSH and LH
If atrophy of the testes occurs during puberty what happens?
Secondary sex characteristics fail to develop
If atrophy of the testes occurs after puberty what happens?
Infertility
Decreased libido, sex drive
Secondary sex characteristics reverse
What can cause testicular atrophy? What else can they cause?
Anabolic steroids
Can also cause sterility
What is the function of the ovaries?
Primary female sex organs
Oogenesis (production of ova)
Synthesize and secrete androgens, estrogens, progesterone
What are the two cell types of the follicles?
Theca cells
Granulosa
What is the function of the follicles?
Synthesize and produce androgens and estrogen
LH stimulates what in the female reproductive system?
Stimulates theca cells to produce androgens
FSH stimulates _____________ in the ____________ cells to convert ______________ into estrogen
Aromatase
Granulosa cells
Androgens
Estrogen is released from ____________ cells and diffuse into the bloodstream or are stored in the _____________ fluid
Granulosa cells
Follicular
____________ deficiency can cause infertility
Aromatase
Some breast cancers are ___________ sensitive meaning estrogen stimulates cancer growth
Estrogen
Treatment of estrogen sensitive cancer may include ___________ inhibitors to inhibit the cancer’s growth
Aromatase
Aromatase inhibitors as treatment for breast cancer is recommended for post-menopausal no pre-menupausal because?
Low estrogen stimulates the pituitary gland to increase LH and stimulate the ovaries to produce more androgens
How does estrogen affect the menstrual cycle?
Accelerates the maturation of the ovarian follicles
Thickens endometrium
Increases uterus contractions
Prepares mucous plug of cervix
How does estrogen affect fertilization?
Prepares sperm to penetrate and fertilize the ovum
Regulates the speed that the ovum travels down the fallopian tube
How does estrogen affect female puberty?
Regulates development and maintenance of female secondary sex characteristics
(narrow shoulders, wide pelvis, wide carrying angle)
Breasts, axillary/pubic hair
How does estrogen affect bone metabolism?
Accelerates epiphyseal plate closure
Positive effect on bone density
Increases calcium retention and osteoblast activity
How does estrogen affect blood chemistry?
increases HDLs, decreases LDLs
Increases coagulation
Increases sodium/water retention
What is the function of progesterone?
Prepare female genitalia for implantation and maturation of fertilized ovum
Maintain pregnancy
What is the target tissue of progesterone?
Uterus
How does progesterone affect the body?
Stimulates growth of uterine muscle
Increases blood supply to endometrium
Decreases uterine muscle activity
Increases basal body temperature
What do high levels of progesterone cause?
Anesthetic effect on CNS
Increases risk of epileptic episodes
Increases basal body temperature
What does a decrease in progesterone cause?
Observed postpartum and luteal phase
Plays role for postpartum depression and PMS
Follicular Phase of menstruation occurs when?
Days 1-14
Early follicular phase
FSH stimulates many follicles to mature and produce estrogen
Mid-follicular phase
A dominant follicle emerges and prepares egg to be released for fertilization
Apoptosis of all other non-dominant follicles
Late-follicular phase
Estrogen positive feedback cycle occurs
Peak levels of estrogen stimulates surge of LH
What day does ovulation occur on?
Day 14
What happens during ovulation?
Surge of LH stimulates release of egg
Follicle becomes corpus luteum
Luteal Phase of menstruation occurs when?
Days 14-28
Early luteal phase
Corpus lutem secretes increasing amount of estrogen, progesterone, and inhibin
Optimize conditions for fertilization
Late luteal phase if fertilization occurs
Fertilized eggs implants into uterus
Corpus luteum secretes hormones to maintain pregnancy until placenta takes over
Inhibin inhibits new cycle from starting
Late luteal phase if fertilization does not occur
Corpus luteum stops secreting hormones
Drop in hormones stimulates new cycle
Hormone levels during Follicular Phase
LH: remains baseline, spikes to signal ovulation
FSH: gradually increases to promote follicle maturation, small peak at ovulation
Estrogen: Peaks just before LH peaks
Progesterone: remains baseline
Hormones levels during Luteal Phase
LH: immediately drops, remains baseline
FHS: immediately drops, remains baseline
Estrogen: quick drop at day 14, starts to increase again (slower/lesser extent)
Progesterone: Begins to increase
Hormone levels during Luteal Phase if no fertilization occurs
Estrogen and progesterone levels drop
If fertilization occurs ______ is secreted by the implanted fertilized egg
hCG
hCG stimulates?
Corpus luteum to continue producing estrogen and progesterone
hCG injection can be used during the luteal phase to?
Promote pregnancy
When does menopause occur?
Ages 45-55
What happens during menopause?
Ovarian tissue gradually ceases to respond to FSH and LH
Decreased estrogen and progesterone during menopause cause?
Atrophy of breast tissue
Thinning of hair
Atrophy of accessory sex organs
Regression of secondary sex characteristics
What risks increase during menopause due to rapid loss of estrogen?
Increased risk of osteoporosis
Increased cardiovascular risk
