CH. 28 Reproductive System Female
Terms in this set (24)
reproductive organs that have job of producing gametes (sex cells)-egg and sperm.. ovaries produce estrogen and progesterone and males produce testosterone.
sex cells that unite to form a new individual. Major task to deplete the number of chromosomes by one half. Sperm and egg have half the normal number of chromosomes- when you have fertilization, you get normal number of chromosomes.
-the process that goes on in the gonads in the production of the gametes is the process of meiosis- does not occur anywhere else= reduction of chromosomes through two meiotic divisions.
gonads produce these sex hormones that affect maturation, development, and changes in activity of the reproductive system organs. In females the hormones are estrogen and progesterone.
time in adolescence where external sex characteristics are prominent, breast enlargement, pubic hair, and reproductive organs become fully functional. gametes begin to mature , gonads secrete sex hormones. Initiated by hypothalamus that secretes GnRH that stimulates anterior pituitary to release FSH and LH which stimulate production of sperm in males, ova in females and also estrogen, progesterone and testosterone.
the female gonads that are paired, oval organs located located within pelvic cavity lateral to uterus.
-2 to 3 centimeters long, 2 cm wide, 1 cm thick
-the cortex contains ovarian follicles while the medulla is composed of areolar connective tissue and contains branches of the ovarian blood vessels, lymphatic vessels, and nerves.
the development of eggs. they develop as structures called ovarian follicles= egg + supporting cell (28 day ovarian cycle)
Cortex of ovary
Contain thousands of ovarian follicles which consist of an oocyte surrounded by follicle cells that support the oocyte. There are different follicles for different stages of development.
consist of an oocyte surrounded by follicle cells that support the oocyte. Start out as small structures, there is a set number in each female at puberty, estimated to be 100s of thousands of these follicles. Plenty of reserve follicles.
at start of cycle, about half of dozen of early follicles grow and enlarge-several layers of follicle cells around egg-during first week of ovarian cycle, under the control of follicle stimulating hormone (FSH from anterior pituitary), stimulate beginning of ovarian cycle and triggers these ovarian follicles to enlarge . They continue to grow but there is in a sense of competition... half a dozen or so of these follicle cells begin to enlarge- at the start of each ovarian cycle,,... by 1-2 weeks only 1 of those follicles continue to grow- the other ones degenerate ... it's thought that they are competition for FSH present.
On day 14- ovulation occurs , controlled by anterior pituitary- sudden increase in LH , that stimulates a mature follicle to release the oocyte plus the surrounding follicle cells- gets released into abdominal cavity- uterine tubes catch oocyte - then transported towards uterus.
After ovulation the remaining follicle cells persist and secrete progesterone and estrogen which target the uterus. Remnant of lots of follicle cells that remain in ovary , they form a structure called- corpus Luteum - for the next 2 weeks of the ovarian cycle, corpus luteum secretes estrogen and progesterone.. estrogen and progesterone tell uterus to prepare for possibility of an egg being fertilized and implanted.
The Menstrual Cycle
-The endometrium of the uterus prepares to receive a fertilized ovum in a cycle of shedding and regrowth.
-Ovarian cycle controlled by FSH and LH from the anterior pituitary.
-Menstrual (uterine) cycle controlled by estrogen and progesterone from the ovarian follicular cells.
Hypothalamus controls anterior pituitary. The anterior pituitary controlling the stages of oogenesis and ovarian follicle development in the ovary. The secretion of estrogen from follicle cells -corpus luteum and progesterone controls the menstrual cycle of the uterus.
Menstrual cycle in uterus
-Menstrual phase: endometrium of uterus is shed (days 1-5 of cycle)
-Proliferative phase: estrogen stimulates regrowth of endometrium (days 6-14)
-Secretory phase: estrogen & progesterone stimulate maturation of endometrium (days 15-28)
-Without fertilization menstrual phase occurs and cycle starts
The superficial 2/3rds of endometrium die off cuz a lack of blood supply and they are shed off and flow out of uterus and into vagina= forms menstrual flow- 1-5 days beginning of menstrual cycle.
As the follicle cells in ovary are starting to multiply and become functional- they secrete more levels of estrogen...the estrogen targets endometrium of uterus to regenerate itself. You have brand new surface epithelium, lamina propia is replenished= growth of blood vessels and areolar connective tissue. There are uterine glands that regenerate also. This is a growth phase in uterus that corresponds with development of ovarian follicles.
At the point of ovulation- day 14 of ovarian cycle- the formation of corpus luteum, corpus luteum cells produce progesterone and estrogen= stimulates increased growth and functionality of endometrium of uterus. The uterine glands starts to secrete glycogen= carbohydrate rich nutrient.. Proliferation of blood vessels in the event of implantation occurs that will form placenta.
This richly highly vascularized and mature uterine glands that are all set if this ovulated egg gets fertilized, there will be a place to implant....if no fertilization, then no implantation, then the corpus luteum turns into scar tissue, as that occurs, the secretion of estrogen and progesterone drops off- that stimulates the beginning of new cycle and flow.
Menstrual cycle: basic
Menstrual phase: 1-5: previous drop of estrogen and progesterone when no fertilization
Proliferative phase: 6-14: the increase level of estrogen causes regeneration of endometrium
Secretory phase: when the corpus luteum forms and secretes estrogen and progesterone= secretory phase, endometrium is functional and prepared for implantation of fertilized egg. Without fertilization theres no implantation, then corpus luteum degenerates and drops off secretion of estrogen and progesterone, that causes the beginning of the menstrual phase... degeneration of thick wall of the uterus... .
Fertilization & implantation
-After ovulation (day 14 of cycle) the secondary oocyte is viable for 24-48 hrs
-Fertilization usually occurs in the oviduct
-Zygote (fertilized egg) takes ~1 week to reach uterus and implant
-Blastocyst - ball of cells from mitosis of zygote
-Implantation stimulates secretion of hCG to maintain corpus luteum (human chorionic gonadotropin - used for pregnancy tests)
Fertilization will usually / or has to occur within 48 hours of ovulation (day 14 of cycle) .. If not fertilized, then degenerates and dies. This released egg is usually captured by uterine tube. And the uterine tube is capable of peristaltic contraction, sends waves of contraction towards uterus. Also ciliated on its epithelium .. Cilia are beating towards the uterus but still that progression of fluid and movement of the egg is slow... so if you do get an egg released, it will be spending several days in uterine tube.. The window of time when fertilization is possible, that egg will normally be in uterine tube and that's where fertilization occurs.
Sperm gets deposited into vagina during intercourse, sperm has to makes its way upstream through uterus , and then have to go into uterine tubes, then they reach their destination of egg.. Fertilization usually occurs in uterine tube . When fertilization occurs, you now have male and female chromosomes join together and as soon as that occurs you have zygote= fertilized egg.. That immediately undergoes mitosis. Series of rapid mitotic cycles.. You end up with a ball of cells.This travel through the uterine tube takes about a week. By one week, the egg has already gone through a series of mitotic divisions= at this point called a blastocyiss. That's the stage it plants in the endometrium of the uterus. When implantation occurs, it sticks to wall of uterus, randomly. ... and then you have an interaction between embryonic cells and maternal cells= forms placenta. .. As soon as implantation occurs, embryonic supporting cells secrete human chorionic gonadotripin from the implanted ovary human chorionic gonadotripin targets the ovaries , tells the corpus luteum not to degenerate and continue to secrete estrogen and progesterone... which is needed since those elevated levels of estrogen and progesterone maintain secretory phase of endometrium which supports the implanted embryo...
they look for presence of human chorionic gondadotropon in urine.. If you detect HCG in urine, implantation has occurred.
When the ovary becomes depleted of primary follicles, the ovarian and menstrual cycles cease. The average age of menopause is 51.
Birth control pill
contain estrogen and progesterone. they depress level of secretion of fsh and lh. without fsh and lh you dont get beginning of ovarian cycle.