regulation of reproduction (10b) Flashcards
(17 cards)
what is spermatogenesis and characteristics
sperm development
begins at puberty, occurs in seminiferous tubules, reduces chromosome number to one member of each pair, changes sperm shape
mechanism of spermatogenesis
spermatogonium (stem cell) has 46 X, splits into primary spermatocyte when it gets signal from FSH (mitosis)
primary spermatocyte has 46X, undergoes meiosis 1 forming secondary spermatocyte
secondary spermatocyte has 23 X, undergoes meiosis 2 forming early spermatids (23 chromatids)
early spermatids change shape and become late spermatids
late spermatids go into lumen of tubules and become spermatozoon then they go into the epididymis
what are the hormones that target the testes and what do they cause
LH: bind to leydig cells (interstitial) and stimulate testosterone production
FSH: stimulates sertoli cells to support sperm maturation
testosterone: sperm production and development of male characteristics
how does the negative feedback control of sperm and testosterone production work
hypothalamus produces GnRH, which stimulates FSH and LH release from APG
LH stimulates interstitial cells to produce testosterone -> testosterone inhibits GnRH and LH production
FSH (& testosterone) stimulate sperm production -> high sperm count stimulates inhibin production by tubules -> inhibin inhibits GnRH and FSH production
mechanism of oogenesis
before birth: oogonium (stem cell) develops into primary oocyte (stopped at prophase 1 of meiosis) which has primary follicle
each month after puberty: primary oocyte (w/ growing follicle which becomes graafian follicle) finishes meiosis 1 and becomes secondary oocyte
secondary oocyte (released from follicle) starts meiosis 2 but stops at metaphase 2 (only completed if egg is fertilized)
what are the three steps of the ovarian cycle
follicular
ovulatory
luteal
steps of the follicular phase
begins when APG releases FSH and LH
primary follicle (containing primary oocyte) secretes estrogen
follicle thickens, fluid containing estrogen accumulates creating a cavity
graafian follicle (mature) results, meiosis 1 occurs
steps of the ovulatory phase
large amount of LH is released from the APG triggers ovulation
mature follicle ruptures and releases the secondary oocyte
steps of the luteal phase
follicle cells form the corpus luteum and remain in the ovary
cells secrete estrogen and progesterone that target uterus
(will degenerate if pregnancy doesnt occur)
what are the steps of the menstrual cycle
menstrual
proliferative (pre-ovulatory)
secretory (post-ovulatory)
steps of the menstrual phase
1st day of menstrual cycle
endometrium detaches and is discarded
steps of the proliferative phase
occurs during follicle growth
controlled by follicle secreting estrogen
increases the thickness of endometrium
phase ends with ovulation
steps of the secretory phase
occurs during corpus luteum development
progesterone and estrogen cause endometrium thickening
arteries and veins develop
hormones involved in reproductive cycle
FSH: follicle development
LH: ovulation, corpus luteum development
estrogen: endometrium and reproductive structures development (sharp drop after ovulation then increase)
progesterone: endometrium maintenance (sharp increase after ovulation)
inhibin: not prominent
what happens after an egg is fertilized regarding hormones
tissues produce HCG (human chorionic gonadotropin) to replace LH -> keeps corpus luteum intact (grows and fills ovary) and hormone levels high, keeps endometrium maintained
HCG and other luteotropins keep corpus luteum going for 8 weeks, after which placenta produces hormones and takes over
in the first week after fertilization what happens
fertilization occurs in fallopian tube and egg moves down to the uterus while undergoing many mitotic divisions
after 7 days, the embryo becomes a blastocyst (hollow ball of cells) and has implanted itself in the endometrium = pregnancy
when can HCG be detected
6 days after conception in serum
10-14 days after in urine
immunoglobin response to HCG in urine is the basis for pregnancy tests
