Module 3B Flashcards
If a Y chromosome is present what antigen is secreted and what duct is the result of this in fetal sex differentiation?
Y chromosome secretes SRY antigen.
Prostate converts testosterone into DHT
Wolffian duct develops into epididymis, vas deferens, seminale vesicle?
If a Y chromosome is not present the absence of what antigen results production of _______ duct?
If no Y chromosome absence of SRY antigen results in lack of MIH which causes the Mullerian duct to develop, eventually into the fallopian tubes ,uterus, and vagina
Which hormones are produced by the testes?
testosterone
Where is testosterone secreted from?
Interstitial cells of Leydig
What are the anabolic effects of testosterone?
Has direct and synergistic affects on growth (by GH and IGF-1, and protein synth)
What are the androgenic effects of testosterone?
Differentiation of male reproductive tract and brain
Regulates development of male accessory organs
Develops secondary sex characteristics
Libido and potency
What signaling system is used within the testes?
paracrine
Where does regulation of testosterone occur?
testes
What two things do you need to have present for spermatogenesis
FSH, and Testosterone
What is the pathway for testosterone and spermatogenesis
- Hypothalamus
- GnRH
- Anterior pituitary-release of FSH and LH
4a. LH stimulates Leydig cells to produce testosterone
4b. FSH stimulates Sertoli cells of seminiferous tubules to convert FSH and testosterone to sperm which is then stored in the epididymis.
What inhibits Production of sperm?
- Negative feedback of Inhibin which is released when the Sertoli cells of the seminiferous tubules have produced enough sperm, will inhibit either the hypothalamus or the anterior pituitary from making more GnRH or FSH
- Too much testosterone will also negatively feedback to just the anterior pituitary and will prevent LH from being released. (reason behind why steroids shrink your balls)
What is the primary function of the oovaries?
Oogenesis
Production of hormones-Estrogen, progesterone, inhibin
What are the two types of cells within the follicle?
Theca cells, and Granulosa cells
What is the function of estrogen?
Prepare for fertilzation: follicle maturation, thicken uterus, change environment to promote fertilization, contraction of fallopian tube.
Development of female sex characteristics
Bone metabolism
Postive CV profle
CNS-social behavior, sexual response, mood
What are the major functions of progesterone?
Implantation, maturation and pregnancy maintenance
What effect do decreased levels of progesterone have on females?
PMS
What does LH do in the
a. 1st 2 weeks of cycle?
b. Surge at 14 days?
c. Weeks 3 and 4?
a. LH is required to swim ovarial follicles to produce estrogen.
b. LH stims ovulation
c. LH stims corpus luteum to release progesterone
What does FSH do in the 1st 2 weeks of cycle?
FSH stims growth of ovarian follicles and estrogen production.
What are the three phases of the menstrual cycle?
Follicular
Ovulation
Luteal
Describe the follicular phase
Days 1-14:
Endometrium thickens
Approx 20 ovarian follicles mature
One eventually becomes “dominant” follicle and others degenerate (apoptosis)
Describe the ovulation phase
Day 14
Surge of LH leads to ovulation, ovum is released from follicle
Prior to ovulation cervical mucous thins and cervix opens slightly (sperm can enter through uterus)
Describe the luteal phase
Days 14-28
Follicle becomes Corpus Luteum
IF FERTILIZATION OCCURS: corpus luteum produces hormones necessary for pregnancy
IF FERTILIZATION DOESN’T OCCUR: CL eventually degenerates, ischemia of endometrium walls and menses occurs
What is the pathway for production of estrogen?
1 LH stims theca cells to produce androgens FSH sims release of aromatase in granulosa cells
- Aromatase converts androgens to estrogens
- Estrogens released from granulosa cell
- Estrogens diffuse into blood stream or are stored in follicular fluid
What is required to convert androgens to estrogen?
Aromatase
What does the placenta over for once it develops?
The corpus luteum
What hormones are considered Placental hormones?
CRH
hPL (human placental lactogens)
Estrogen and Progesterone (early in pregnancy corpus luteum remainder of pregnancy produced by placenta)
What occurs in menopause?
Gradual increase of time between menstrual cycles due to LSH and FSH receptors becoming less sensitive over time.
