Ch. 28 - Female Reproductive System Flashcards
Gametogenesis
process of forming human sex cells. Begins with cell division, meiosis. Is a similar process in both females and males.
sex cells
gametes
female gametes
oocytes
male gametes
sperm
Overview of Meiosis
sex cell division that has 4 haploid daughter cells genetically different from parent cell. start with diploid parent cell (46) and produces haploid daughter cells (23) called gametes. Includes crossing over where genetic material is exchanged between homologous chromosomes to get genes from both parents in one chromosome.
Mitosis
somatic cell division, produces 2 genetically identical diploid daughter cells and does not cross over.
Interphase
cell phase prior to meiosis where dna on each cell is replicated. The replicated chromosomes are now composed of 2 sister chromatids (structures with identical copies of dna)
centromere
place where sister chromatids are attached.
meiosis 1 - reduction division
begins after interphase, 4 phases plus cytokinesis. Homologous pairs of chromosomes separate when cell divides Results in 2 cells, each with 23 chromosomes of replicated sister chromatids held together at centromere
Prophase 1
first phase of meiosis I. Pairing up homologous replicated chromosomes that bind to form a tetrad (2 sets of 2 sister chromatids) through process of synapsis. Crossing over then occurs with maternal chromosome and paternal chromosomes to ensure diversity. Ends with breakdown of nuclear envelope.
Metaphase I
second phase, lining up of homologous pairs of tetrad on cell midline. It has random alignment. Spindle fibers form by microtubules and extend from centrioles to centromeres of each homologous replicated chromosomes.
Anaphase I
third phase, homologous pairs of chromosomes separate and are pulled apart to opposite ends of cell. Each daughter cell receives half number of chromosomes called reduction division. Each chromosome still with 2 sister chromatids.
Telophase 1 and cytokinesis
reformation of nuclear envelope, cleavage furrow forms, cell cytoplasm divides in cytokinesis to produce 2 new cells. The daughter cells have 23 replicated chromosomes each with 2 sister chromatids bound together.
independent assortment
refers to the random alignment and whether maternal or paternal ends up on one side or the other in metaphase I.
Meiosis II
functions to separate sister chromatids to become single chromosomes in haploid cell instead of replicated ones.
Prophase II
resembles prophase I, breaks nuclear envelope, chromosomes collect together, and no crossing over. No homologous chromosome pairs are present; they were already separated.
Metaphase II
Spindle fibers extend from centrioles to centromeres and sister chromatids align along cell midline
Anaphase II
sister chromatids are pulled apart and single stranded chromosomes separate to opposite poles
Telophase II and cytokinesis
reformation of nuclear membrane, cleavage furrow forms to produce 4 haploid cells; 22 autosomes and 1 sex chromosome. Mature into oocytes and sperm.
Failure to separate homologous chromosomes or sister chromatids
results in gamete with 22 or 24 chromosomes most commonly which causes the individual to have 45 or 47 chromosomes instead of 46.
monosomy
individual with 1 copy of a chromosome (45 chromosomes)
Trisomy
individual with 3 copies of one chromosome. (47 chromosomes)
down syndrome
intellectual disability, slanting eye creases, heart defects, poor muscle tone, short stature. Due to nondisjunction of oocyte (more common) or sperm. Incidence increases with mother’s age.
primordial follicles
most primitive type of ovarian follicle. Has primary oocyte and single flattened layer of follicle cells. primary oocyte arrested in first meiotic prophase. 1.5 million present at birth.
primary follicle
forms from maturing primordial follicle. Primary oocyte with single layer of cuboidal follicular cells, now called granulosa cells. Primary follicle secretes estrogen as it matures and stimulates changes in uterine lining. Surrounding primary oocyte is zona pellucida; a translucent structure containing glycoproteins.
zona pellucida
translucent structure containing glycoproteins immediately surrounding primary oocyte
secondary follicle
forms from primary. Has primary oocyte with many layers of granulosa cells. Also has thecal cells on periphery of follicle to help control follicle development and secrete androgens converted to estrogen by granulosa cells.
synapsis
process of pairing up of homologous replicated chromosomes in meiosis I
nondisjunction
failure of separation of homologous chromosomes or sister chromatids
thecal cells
on periphery of follicle and helps control follicle development. Secretes androgens converted to estrogen by granulosa cells
antral follicle
forms from primary follicle. The primary oocyte has many layers of granulosa cells and a fluid filled space called the antrum. In the antrum, serous fluid increases as ovulation nears and oocyte is forced to one side of follicle. Oocyte is surrounded by cluster of follicle cells called cumulus oophorus and immediately surrounding oocyte is zona pellucida and corona radiata.
corona radiata
external to zona pellucida; is the innermost layer of cumulus oophorus cells.
mature follicle
forms from secondary follicle and contains secondary oocyte surrounded by zona pellucida and corona radiata and has numerous layers of granulosa cells. Also has fluid-filled antrum and has completed meiosis I. It isarrested in second meiotic metaphase and one is formed every month.
Corpus luteum
forms from remnants of follicle after mature follicle ruptures and oocyte is expelled. It secretes sex hormones progesterone and estrogen to stimulate buildup of uterine lining and prepare uterus for possible implantation of fertilized oocyte.
corpus albicans
formed from regressed corpus luteum. White connective tissue scar with most structures completely resorbed.
Oogenesis and Ovarian cycle definition
maturation of a primary oocyte to secondary oocyte, occurs in stages over life of a female.
Oogenesis before birth
ovary contains primordial germ cells or oogonia. follicles within ovarian cortex at birth and remain diploid cells. divide by mitosis to produce primary oocytes and cells start meiosis, but they are arrested in prophase I. Cells are now primary oocytes. 1.5 mil are arrested in prophase until after puberty.
Oogenesis, Childhood
Ovaries are inactive with no follicles developing. Includes atresia or regression of some primordial follicles. By puberty, 400,000 follicles remain in ovaries.
Oogenesis and Ovarian cycle from puberty to menopause
Hypothalamus release of gonadotropin releasing hormone that stimulates release of FSH and LH. These produce a monthly sequence of events, the ovarian cycle. The ovarian cycle occurs in 3 steps, follicular, ovulation, and luteal phase.
Follicular phase
days 1-13 of 28 day ovarian cycle. Around 20 primordial follicles stimulated to mature into primary follicles by LH and FSH. Unclear why some are stimulated and some are not. Granulosa cells release inhibin to hell inhibit further FSH production and prevents excessive follicle development. Usually only one primary follicles mature into secondary follicles. Volume of fluid increases within follicle antrum and oocyte forced to one side and primary oocyte in antral follicle finishes meiosis I and forms 2 cells. One of the cells is a polar body that is nonfunction and regresses and second becomes secondary oocyte which reaches metaphase before being arrested again. Will complete meiosis if fertilized.
Ovulation
release of secondary oocyte from mature follicle. Occurs on day 14-28 and usually only one ovary ovulates per month. This is induced with peak in LH secretion and antrum increases in size until ovarian surface thins and ruptures, expelling secondary oocyte.
Luteal Phase
remaining follicle cells become corpus luteum on days 15-28 of cycle.
Corpus luteum
temporary endocrine gland secretes progesterone and estrogen to build up uterine lining for fertilized oocyte. Life span of 10-13 days if oocyte not fertilized.
Corpus luteum regression
occurs during luteal phase and causes drop in secreted progesterone and estrogen and causes shedding of uterine lining (menses)
menarche
first menstrual cycle around age 11-12
menopause
women cease cycling for 1 year with normal onset around 45-55. No more ovarian follicles remain or follicle maturation stops. Significant amounts of progesterone and estrogen no longer secreted and uterine lining no longer growing. No more periods.
Regulation of the ovarian cycle in depth
- hypothalamus secretes GnRH and stimulates ant. pit. to secrete FSH and LH.
- FSH and LH target ovaries and stimulate follicular development. Cause maturation of follicles and affects secretion of other hormones.
- Maturing ovarian follicles secrete inhibin and estrogen and negative feedback on hypothalamus and ant. pit.
- Estrogen assists development of mature ovarian follicle
- Mature follicle produces a larger amount of estrogen and positive feedback initiated
- Feedback loop results in an LH surge from ant. pit. cant have ovulation without surge.
- Corpus luteum forms from ovulated follicle.
- Corpus luteum secretes progesterone, estrogen, inhibin. Inhibits hypothalamus and ant. pit. and builds uterine lining. degenerates in 10-13 days if not fertilized
- Cycle repeats. LH levels reduced and lowered estrogen, progesterone, and inhibin. Hypothalamus secretes GnRh to start new cycle.
pre-embryo
if secondary oocyte is fertilized and implants. Starts secreting human chorionic gonadotropin (hCG) which mimics effects of LH and continues to stimulate corpus luteum to maintain uterine lining. Placenta produces its own progesterone and estrogen after 3 months and corpus luteum regresses into corpus albicans.
uterine tubes
extend laterally from both sides of uterus toward ovaries and transport ovulated oocyte to uterus. It is covered and suspended by mesosalpinx (a specific part of broad ligament)
mesosalpinx
specific superior part of broad ligament of uterus that suspends fallopian tubes.
infundibulum
free, funnel-shaped, lateral margin of uterine tube with numerous fingerlike folds called fimbriae. Enclose ovary only at time of ovulation.
Ampulla
expanded region of tube medial to infundibulum, fertilization typically happens here.
Isthmus
region of tube extending medially from ampulla
Uterine part of tube
extends medially from isthmus and penetrates wall of uterus.
Wall of uterine tube
contains mucosa, muscularis, and serosa.
Mucosa of fallopian tube
simple ciliated columnar epithelium with underlying layer of areolar CT. Linear folds reducing size of tube lumen and has cilia on apical surface. Cilia beat in direction of uterus to draw oocyte towards uterus.
Muscularis of fallopian tube
inner circular layer and outer longitudinal muscle layers that contract to propel pre-embryo through uterine tube if fertilized.
Serosa
external serous membrane covering uterine tube.
Uterus
pear shaped muscular organ. Uterus lumen connects to uterine tubes superolaterally and connects to vagina inferiorly. Angled anterosuperiorly across superior bladder (anteverted). May shift posterosuperior position in older woman.
Uterus functions
implantation site for pre-embryo. supports, protects, and nourishes developing embryo. and forms vascular connection that develops into placenta. It also ejects fetus at birth and sheds lining if oocyte not fertilized.
Fundus of uterus
broad superior region between attachments of uterine tubes
Body of uterus
middle region, major part of organ, thick wall of smooth muscle.
Isthmus of uterus
narrow constricted inferior region superior to cervix
Cervix of uterus
narrow inferior-most part of uterus that projects into vagina.
Cervical canal
narrow channel within cervix
External Os
inferior opening of cervix into vagina, covered by nonkeratinized stratified squamous epithelium
internal os
superior opening of cervical canal.
mucous plug at external os
formed by mucin-secreting glands, prevents pathogens from invading uterus from vagina. Thins around ovulation time for easier sperm penetration.
Tunics of uterine wall
perimetrium, myometrium, endometrium
perimetrium
outer tunic, a serosa. Continuous with broad ligament.
myometrium
thick, middle tunic of uterine wall, 3 intertwining layers of smooth muscle
Endometrium
innermost mucosal tunic of uterus. Simple columnar epithelium and underlying lamina propria. Lamina propria has compound tubular glands, uterine glands. Deeper basal layer is adjacent to myometrium and is permanent layer. The more superficial functional layer begins at puberty and grows from basal layer under influence of estrogen and progesterone. Sheds if no fertilization
Vagina
thick-walled, fibromuscular tube that connects uterus with outside of body. Most inferior part of female reproductive tract. Functions as birth canal, menstruation passageway, receives penis. Supplied by vaginal arteries and drainage via vaginal veins. It has a thin wall with 3 tunics: inner mucosa, middle muscularis, outer adventitia.
Mucosa of vagina
nonkeratinized stratified squamous, highly vascularized lamina propria. Has acidic secretions to prevent infection and inferior region has numerous transverse folds
vaginal orifice
lumen near vaginal opening; part of mucosa
hymen
vascularized membranous barrier; part of mucosa
Muscularis of vagina
has outer and inner layers of smooth muscle
adventitia
contains inner elastic fibers, outer layer of areolar CT.
Menstrual (uterine) cycle
cyclical changes in endometrial lining influenced by estrogen and progesterone. 3 distinctive phases: menstrual phase, proliferative phase, secretory phase. Cycle usually between 21-35 days.
Menstrual phase
days 1-5 of cycle. Sloughing off of the functional layer.
Proliferative phase
days 6-14 of cycle with development of new functional layer of endometrium, overlaps time of follicle growth and ovary estrogen secretion.
Secretory phase
days 15-28 of cycle with increased progesterone secretion from corpus luteum to increase vascularization and uterine gland development. If fertilization does not occur, corpus luteum degenerates and functional layer sloughs off.
Mammary glands
composed of tubuloalveolar exocrine gland. Secretes breast milk that contains proteins, fats, and lactose sugar. It is subdivided into lobes and then further into lobules. Secretory units are alveoli and they produce milk and become more numerous and larger during pregnancy.
Lactiferous ducts
larger channels of merged ducts, draining single lobe, expands to form lactiferous sinus where milk is stored
Lactation
release of breast milk in response of internal and external stimuli. Start to produce after giving birth.
Prolactin
produced in anterior pit. and responsible for milk production, with increase, mammary gland forms more and larger alveoli
Oxytocin
produced by hypothalamus and released from post. pit. Responsible for milk ejection
Female sexual response
begins with excitement phase where reproductive organs are engorged with blood (clit, labia, etc.). Nipples and uterus erect and vestibular glands and vaginal wall produce more mucus with slight constriction of vaginal wall. Increase in hr, bp, and resp. rate.
second stage is orgasm, with intense pleasure and tension release, rhythmic contraction of vagina and uterus.
third stage is resolution where uterus returns to normal position, vagina relaxes, and excess blood leaves tissues. No refractory period in women.
