endoReproFemale Flashcards
(34 cards)
estrogen
Essential for ova maturation and release
Establishment of female secondary sexual characteristics
Essential for transport of sperm from vagina to fertilization site in oviduct
Contributes to breast development in anticipation of lactation
progesterone
Important in preparing suitable environment for nourishing a developing embryo/fetus
Contributes to breasts’ ability to produce milk
ovarian cycle
Average ovarian cycle lasts 28 days
Normally interrupted only by pregnancy
Finally terminated by menopause
ovarian cycle phases alternating
Follicular phase
Dominated by presence of maturing follicles
Luteal phase
Characterized by presence of corpus luteum
follicular phase
• Operates first half of cycle
• Granulosa cells of some primary follicles proliferate
• Oocyte inside each follicle enlarges
• Theca cells in follicle secrete increased amounts of estrogen
Rapid follicular growth continues during follicular phase
One follicle usually grows more rapidly and matured about 14 days after onset of follicular development
Follicle ruptures to release oocyte from ovary
Event is called ovulation
Released oocyte enters oviduct where it may or may not be fertilized
luteal phase
• Last 14 days of ovarian cycle
• Old follicular cells undergo structural transformation to form corpus luteum
• Becomes highly vascularized
• Becomes fully functional within four days after ovulation
Continues to increase in size for another four or five days
• If released ovum is not fertilized and does not implant, corpus luteum degenerates within about 14 days after its formation
FSH rise signals
During follicular phase, the rise in FSH signals ovarian follicle to secrete more estrogen
Rise in estrogen feeds back to inhibit FHS secretion which declines as follicular phase proceeds
LH rises in follicular phase
As it peaks in mid-cycle, it triggers ovulation
corpus lute secretes what during luteal phase
progesterone and estrogen
Progesterone output inhibits release of FSH and LH
Low LH – corpus luteum degenerates Progesterone levels decline
FSH can start to rise again, initiating new cycle
control of ovulation and subsequent luteinazation of the ruptured follicle are triggered by…
an abrupt, massive increase in LH secretion
This LH surge brings about four major changes in the follicle:
during the ovulation..
Halts estrogen synthesis
Reinitiates meiosis in the oocyte of the developing follicle
Triggers production of locally acting prostaglandins Differentiation of follicular cells into luteal cells
LH and corpue luteum
LH “maintains” the corpus luteum; that is, after triggering development of the corpus luteum, LH stimulates ongoing steroid hormone secretion by this ovarian structure
Under the influence of LH, the corpus luteum secretes both progesterone and estrogen, with progesterone being its most abundant hormonal product
uterine or menstrual cycle
3 phases
reflects hormonal changes during ovarian cycle average 28 days - menstrual phase - proliferative phase - secretory or progetational phase
menstrual phase
discharge of blood and endometrial lining debris from vagina
First day of menstruation is considered start of new cycle
• Coincides with end of ovarian luteal phase and onset of follicular phase
proliferative phase
• Begins concurrent with last portion of ovarian follicular phase
– Endometrium starts to repair itself and proliferate under influence of estrogen from newly growing follicles
• Estrogen-dominant proliferative phase lasts from end of menstruation to ovulation
• Peak estrogen levels trigger LH surge responsible for ovulation
Secretory or Progestational Phase
Uterus enters this phase after ovulation when new corpus luteum is formed
Corpus luteum secretes large amounts of progesterone and estrogen
Progesterone
Converts endometrium to highly vascularized, glycogen- filled tissueEndometrial glands actively secrete glycogen
If fertilization and implantation do not occur
Corpus luteum degenerates
New follicular phase and menstrual phase begin once again
menopause
Cessation of woman’s menstrual cycle
• Usually occurs between ages of 45 and 55
• Midlife hypothalamic change may trigger onset of menopause
climacteric
Period of transition
menopause —Preceded by period of progressive ovarian failure
Increasingly irregular cycles
Dwindling estrogen levels
Loss of estrogen primarily affects skeleton and cardiovascular system
fertilization site
oviduct upper third in the ampulla
Must occur within 24 hours after ovulation
Sperm usually survive about 48 hours but can survive up to five days in female reproductive tract
first sperm to reach ovum ..
Fuses with plasma membrane of ovum
– Triggers chemical change in ovum’s surrounding membrane that makes outer layer impermeable to entry of any more sperm
– Head of fused sperm gradually pulled into ovum’s cytoplasm
– Within hour, sperm and egg nuclei fuse
• Fertilized ovum now called a zygote
more fert
Fertilized ovum divides mitotically
Within week grows and differentiates into blastocyst capable of implantation
Blastocyst implants in endometrial lining by means of enzymes released by trophoblasts
Enzymes digest endometrial tissue
Carve hole in endometrium for implantation of blastocyst
Release nutrients from endometrial cells for use by developing embryo
placenta
Organ of exchange between maternal and fetal blood
Acts as transient, complex endocrine organ that secretes essential pregnancy hormones
pregnancy hormones (3)
Human chorionic gonadotropin – maintains corpus luteum until placenta takes over function in last two trimesters
Estrogen – essential for maintaining normal pregnancy
Progesterone – essential for maintaining normal pregnancy
functions of placenta
• The placenta performs the functions of the digestive system, the respiratory system, and the kidneys for the “parasitic” fetus
– Nutrients and oxygen diffuse from the maternal blood across the thin placental barrier into the fetal blood, whereas carbon dioxide and other metabolic wastes simultaneously diffuse from the fetal blood into the maternal blood