Repro-Physiology Flashcards
What causes erection?
Parasympathetic impulses from S2-S4 cause NOS to form NO which causes smooth muscle relaxation, an efflux of calcium, and vasodilation to promote an erection.
This is maintained until norepinephrine allows calcium back into the cell, resulting in vasoconstriciton and PDE5 breaks down cGMP
What are PDE5 (phosphodiesterase 5) inhibitors that prevent breakdown of cGMP to help maintain an erection?
Sildenafil and Verdenafil FILL the penis
What are some AEs of PDE5 inhibitors?
Headache, flushing, dyspepsia, impaired blue-green color vision, and hypotension
“Hot and Sweaty,” but then Headache, Heartburn, and Hypotension
What stimulates ejaculation in a male?
Sympathetic nervous system via the hypogastric nerve stimulates emission and
the pudendal nerve stimulates ejaculation
Describe spermatogenesis
Spermatogonia are produced in the millions during gestation and line the periphery of seminiferous tubes (46,2N). Starting at puberty, these undergo many mitoses to produce primary spermacytes (46, 4N), which undergo meiosis I to form secondary spermacytes (23,2N), and the meiosis II to form spermatids (23,N). Following spermatogenesis, spermiogenesis causes maturation of spermatids to form mature spermatozoon via the loss of cytoplasmic contents and gain of an acrosomal cap
Full development takes 2 months
What other cells can be found within seminiferous cells?
Sertoli cells, aka nurse cells
What do Sertoli cells secrete?
They secrete:
inhibin which inhibits FSH production from the anterior pituitary
androgen-binding protein (ABP), which helps maintain local levels of testosterone
AMH which causes regression of the mullerian ducts during differentiation
What are the other roles of sertoli cells?
- support spermatogenesis
- form tight junctions to form the blood-testis barrier
- can transform testosterone into estrogen some via aromatase
T or F. Sertoli cells are temperature sensitive
T. There is decreased sperm and inhibin production when temp rises, such as in the case of varicocele and cryptorchidism
What are the roles of Leydig cells?
These are located in the intersitium between seminiferous tubules and secrete testosterone (unaffected by temperature)
What is Cililary dyskinesia and Kartagener syndrome marked by?
impaired sperm motility
Again, testosterone is made by leydig cells. What are the main roles of testosterone?
- differentiation of the male internal genital tract (except the prostate)- epididymis, vas deferens, seminal vesicles
- deepening of the voice at puberty
- libido
- closing of the peiphyseal plates (mainly via estrogen converted from testosterone)
- growth spurt at puberty (penis, seminal vesicles, sperm, muscle, RBCs)
How is DHT made from testosterone?
via 5a-reductase
What are the roles of DHT?
- differentiation of the external genitalia (penis, scrotum) and prostate
- balding and hair growth
- sebaceous gland activity
What are the results of extensive exogenous testosterone use?
Feedback inhibition of the HPG axis (at BOTH the anterior pituitary and the hypothalamus) which decreases sperm production and causes tesicular atrophy and azoospermia
What is azoospermia?
Azoospermia is the medical condition of a man when sperm count is equal or less than 15 million/ml in his semen
What are the main tissue sources of estrogen?
ovaries (via 17B-estradiol production), placenta (estriol), and adipose tissue (via aromatase)
How is estrogen made in adipose tissue?
from testosterone via aromatase
Give an overview of the two-cell production of ovarian estrogen
Pulsatile release of GnRH from the hypothalamus causes pulsatile LH release from the anterior pituitary which stimulates cholesterol (mainly from the liver LDL) mobilization and the action of cholesterol desmolase, which promotes conversion of cholesterol to androstenedione in THECA cells. Androstenedione then diffuses into granulosa cells, where FSH stimulates estrogen production from testosterone
How does estrogen work at a receptor tissue?
It binds to cytoplasmic receptors (alpha and beta) and translocates to the nucleus to induce transcription
What are the main functions of estrogen?
Estogen promotes development of the female genital tract, as well as follicle growth in the ovaries during the follicular phase of the menstrual cycle, and proliferation of the endometrium in the follicular phase
What are the effects of estrogen on cholesterol levels?
increases HDL but lowers LDL
What are the main roles of progesterone?
Progesterone is the major hormone of the luteal phase of the menstrual cycle and is secreted primarily by the corpus luteum. Its main roles include increased vascularization of the endometrium to promote implantation and production of thick cervical mucus, which inhibits sperm entry into the uterus
It also prevents labor by repressing prostaglandin activity (note that prostaglandin activity is also responsbile for the pain of menses)
When is female body temp typically higher during the menstrual cycle? Why?
During the luteal phase because progesterone tends to increase body temp
How does progesterone affect estrogen receptor expressivity?
More progesterone= less estrogen receptors (while more estrogen= more progesterone receptors)
Elevation of progesterone is indicative of _______
ovulation
What are the Tanner stages of sexual development?
I. Childhood
II. Pubic hair appears (pubarche); breast buds form (thelarche)
III. Pubic hair darkens and becomes curly; penis size increases and breasts enlarge
IV. Penis width increases, scrotal skin darkens, development of glans penis, and raise areolae appear
V. Adult, areolae are no longer raises
What is the average menstrual cycle length?
21-35 days, average of 28. The follicular phase is the only part that can vary in length. The luteal phase is always 14 days.
Ovulation + 14 days always= menses
What is oligomenorrhea?
35+ day cycle
What is polymenorrhea?
less than 21 day cycle
What is metorrhagia?
irregular but frequent menses
What is menometrorrhagia?
heavy, irregular menstruation at irregular intervals
Describe the menstrual cycle
Study the deck in repro week 1 on menstrual cycle for STEP
What is Mittelschmerz?
when blood from a ruptured follicle or follicular enlargement causes peritonel irritation that can mimic appendicitis. This occurs MID-cycle
Describe oogenesis
During gestation millions of oogonia (46, 2N) are produced and mitosis produces primary oocytes (46,4N) (many of which regress) that arrest in prophase of meiosis I until puberty. Once puberty begins, meiosis I will complete at ovulation to form a secondary occyte (23,2N) which is then arrested in metaphase of meiosis II until fertilization occurs, at which time a haploid ovum (23,N) is produced (along with a second polar body)
What happens to the secondary oocyte is fertilization doesnt occur?
it will degenerate if fertilization doesnt occur within 1 day
Where does fertilization most commonly occur?
in the ampulla of the fallopian tubes within 1 day of ovulation
NOTE: Gestational age is calculated from the date of the last menstrual period, while embryonic age is calculated from the date of conception
When does implantation occur?
typically within 6 days of fertilization
NOTE: Trophoblasts secrete hCG, which is detectable in blood 1 week after conception, and on home tests in urine within 2 weeks. hCG levels peak at 8-10 weeks og gestation
What disinhibits lacation after labor?
the drop in progesterone allows suckling to produce upregulation of oxytocin and prolactin
Remember, prolactin makes the milk (and prevents reproductive function), and oxytocin helps squeeze the myoepithelial cells in the breast to get it out (aka letdown)
What is the source of hCG?
syncytoptrophoblasts from the placenta
What are the functions of hCG?
maintain the corpus luteum and thus progesterone for the 1st trimester by acting like LH.
In the 2nd-3rd trimesters, the placenta makes its own estriol and progesterone and the corpus luteum regresses.
How does menopause affect hormones?
It causes estrogen to drop as follicles drop in number, causing anovulatory cycles around menopause. The loss of estrogen causes FSH and some LH (and GnRH) levels to skyrocket
Hyperelevated FSH is specific for menopause
What are the symptoms of menopause?
Menopause causes HHAVOC:
Hirsutism
Hot flashes
Atrophy of the Vagina
Osteoporosis
Coronary Artery Disease
Why would menopause cause hirsutism?
The main source of estrogen in menopause becomes peripheral conversion of androgens, which causes increased androgens and thus hirsutism
Menopause before 40 indicates what?
potentially premature ovarian failure
Elevated hCG during pregnancy could suggest what?
multiple gestations, hydatidiform moles, choriocarcinomas, or Down syndrome
Suppressed hCG during pregnancy could suggest what?
ectopic/failing pregnancy
Edward syndrome
Patau Syndrome
Assessment of newborn vital signs following labor via a 10-pt scale evaluated at 1 min and 5 min. Apgar less than 7 requires further evalulation (could develop longterm neurologic damage)
What is a low birth weight defined as?
Less than 2500g caused by prematurity or intrauterine growth restriction (IUGR).
What are some associations of low birth weight?
increased risk of SIDS and overall mortality
May cause impaired thermoregulation and immune function, hypoglycemia, polycythemia, and impaired emotional development
What are the contents of breast milk?
Breast milk is ideal for infants under 6 months old. It contains immunoglobulins (mostly IgA), macrophages, and lymphocytes
How is breast milk advantageous to a newborn?
It reduces infant infections and decreases the risk for development of asthma, allergies, DM, and obesity
How is breast milk advantageous to a mother?
it reduces the risk of breast and ovarian cancer and facilitates mother-child bonding
Exclusively breastfed infants require _______ supplementation
Vit D
