lecture 15: reproductive system II Flashcards
what are the functions of of the reproductive system?
- produce ovaries
- receive sperm, facilitate fertilizations
- house and nourish developing embryo, give birth ( development)
- lactate, feed young ( caring for newborns)
- make cells and fertilizations + development and care post birth
what are ovaries
female gonad (either side) responsible for making egg cells or ova
how are ovaries held
held in place by several ligaments, not just floating
what do ovaries produce
gametes ( egg cells) via oogenesis -> oocyte
sex hormones - estradiol, progesterone
oviducts ( fallopian tubes)
- tubes between ovaries & uterus
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what is the function of oviducts
- collects secondary oocytes from the ovary
- movenet though oviduct is added by cilia and contractions
what is the site of oviducts
- site of fertilization ( where sperm encounters 2° oocyte)
- doesn’t become egg until after fertilizations
uterus
- pear- shaped, - size of fist
- 2 layers: myometrium: thick wall of smooth muscle
- endometrium: lines lumen daces inner cavity
the uterus is the site of ….
embryonic development: (expands during pregnancy’s), highly elastic
endometrium
- lines lumen - connective tissue, gland, blood vessels
- thickens each month - prepare for pregnancy: (embryo arrives in uterus, implants in endometrium, responsible for nutrients for embryo
- fertilization -> embryo implants
- no fertilization -> sloughed off (lost) -> menstruation (shedding of endometrium lining)
cervix
- closes uterus and seperates it from vagina
- comonn site of cancer
vagina
- elastic muscular tube
- extends to outside of body
- receives penis and sperm ( during intercourse)
- birth canal ( fetus goes through vagina from uterus)
vulva
- external genitalia
- covers external openings
oogenesis
- development of mature eggs (making egg cells)
oogenesis in embryo
- primordial germ cells (2n)
- mitosis -> oogonia (2n)
- form during development, no new oogonia after birth
- mitosis -> 1 ° oocyte (2n)
1° oocyte ( forms during embryonic development)
- begin meiosis
- arrest in prophase I
- at birth, avg female: 1-2 million 1° oocytes have arrested in prophase I of meiosis, all wont last
- 200k left by sexual maturity
- dormant in prophase I until acted on by hormones after puberty and restart process of oogenesis
oogenesis after puberty
-occurs in follicle: structure within ovary, group of cell with 1° oocyte in the middle
the follicle contains
- 1° oocyte on inside
- shell of lots of follicle cells - protective barrier
- zona pellucida
zona pellucida
thick glycoprotien layer between follicle cells & oocyte (separates outer and inner layers)
each month
a) 6-12 follicles matures
b) primary oocyte grows, follicle cells proliferate
c) After ~1 week - largest of follicle (wins the race) continues, others stop, disintegrates
1° oocyte division
- once mature, release cell into oviduct
- restart and completes meiosis I 8-10 hours before release (ovulation)
- unequal cytokinesis
- starts meiosis II
- arrests at metaphase II
unequal cytokinesis
- 1 one polar body (n) very small, gets rid of half the genome
- one 2° released from follicle during ovulation
ovulation
a) Once 1st meiotic division complete
b) As 2° oocyte matures → follicle that contains it moves to surface of ovary
c) Follicle cells secrete fluid, estrogens, proteolytic enzymes → break down ovary wall
d) 2° oocyte ejected into oviduct
(1) Follicle ruptures
corpus luteum
“yellow body” remnants of follicle that is left behind
portionof follicle left in ovary after ovulation
corpus luteum develops into
temporary endocrine glands
the corpus luteum secretes
- estrogens
- progesterone (1000x more than estrogens)
2°
a) If sperm enters (fertilized) → completes meiosis II → mature egg contain sperm head (with sperm genome) - oogenesis complete
b) If no sperm enters → disintegrates
(1) Corpus luteum dies (luteolysis) → Menstruation (triggers breakdown of endometrium lining)
c) Getting rid of temporary endocrine gland → New follicle next
