Female reproductive system

OvariesIn the upper pelvic cavityProduce eggs (ova, which is plural for uvum)Has an outer cortex and an inner medullaCortex contains follicles, each with a

potential egg cellFemales are born with about 400 000

follicles…and that is all she will ever have!Only about 400 ever mature to produce an

ovumGenetic defects in children of older mothers

may be due to “older” eggs

Figure 37.7 pg 914

Oviducts (fallopian tubes)Have fimbriae that sweep ovum into oviduct

(sometimes it misses and ends up in abdominal cavity, and sometimes gets fertilized there!)

Unfertilized eggs live only 48 hoursOvum propelled down oviduct by cilia and

muscular contraction of oviductFertilization occurs in oviductTakes 3 – 5 days for it to get to the uterusSometimes it gets stuck in oviduct and

develops there (ectopic pregnancy)

Uterus: lies above urinary bladder

Development of the embryo occurs here

Has a lining (endometrium) which helps form the placenta

Endometrium has 2 layers:Basal and functionalFunctional layer varies in thickness and is shed monthly

Endometrium is shed monthly f no fertilization occurs (menstruation)

CervixMuscular band that separates vagina from

uterusIt is designed to hold the fetus inVaginaReceives penis in copulationLies in folds that can extend (especially

important during birth!!!

External genitaliaVulva:

Labia majoraLabia minora

Clitoris:Analogous to glans penis in males. Also becomes filled with blood and become erect

Brain Break!!!Mom & Dad decided that the only way to pull off a

Sunday afternoon quickie with their ten-year-old son in their small apartment was to send him out on the balcony and order him to report on all the neighborhood activities. The boy began his commentary as his parents put their plan into operation. "There's a car being towed from the parking lot," he said. "An ambulance just drove by. " A few moments passed. "Looks like the Andersons have company," he called out, "Matt's riding a new bike and the Coopers are having sex." Mom and Dad shot up in bed. "How do you know that?" the startled father asked. "Their kid is standing out on the balcony too," his son replied.

Hormonal regulation in females(see pg 916 fig 37.8)

2 cycles:Ovarian cycle

(Follicular phase :days 1 – 13)(Luteal phase: days 15 – 28)

Uterine cycle(Menstruation: days 1 – 5)(Proliferative phase: days 6 – 13)(Secretory phase: days 15 – 28)

Day 14 in both cycles is OVULATION

Hormones involvedGnRh (hypothalamus)FSH or follicle-stimulating hormone(interior

pituitary)LH or lutenizing hormone (anterior pituitary)Estrogen (ovaries)Progesterone (ovaries)

Days 1 - 13GnRH stimulates production of LH and FSHFSH causes follicle to developThe follicle secretes mostly estrogenAs blood estrogen rises, negative feedback

slows the release of FSHTherefor the follicle phase ends (which is

marked by ovulation)The estrogen production causes

endometrium to thicken and become vascular

Days 15 - 28LH secretion more prominent than FSHLH promotes development of corpus luteum

(which secretes progesterone)As blood progesterone level rises, negative

feedback slows the release of LHThis causes corpus luteum to disintegrateAnd therefor the luteal phase ends (marked

by the onset of mensturation)

*NoteBoth FSH and LH are present at all times

in the cycle. They simply rise and fallBoth estrogen and progesterone are

present at all times. Estrogen is the main hormone in the first half of the cycle and progesterone is the main one in the second