Chapter 46: Reproduction Flashcards
asexual reproduction
new individuals w/out sex; cloning
sexual reproduction
fusion of haploid gametes to form diploid zygote
internal fertilization
gametes meet in female reproductive tract
external fertilization
gametes meet outside body; can only take place in aquatic environments
fission
one individual splits into two of similar size
budding
one individual splits into two of similar size
fragmentation
breakage, followed by regeneration
parthenogenesis
offspring develop from unfertilized eggs
asexual reproduction benefits and losses
benefits: favored in stable environments
losses: not as adaptable to changing environments
hermaphrodites
species have both male and female gonads
gonochoristic
male and female species have different gonads
spawning
both sperm and eggs released to water
benefits of internal fertilization
prevents gametes from drying out; allows for terrestrial reproduction
gametogenesis
production of gametes
oogenesis
production of female gametes (ovum)
spermatogenesis
production of male gametes (sperm)
differences between spermatogenesis and oogenesis
- number of gametes formed by meiosis
- timing of meiotic divisions
- pace of meiotic divisions
penis
male sex organ; urethra and erectile tissue
baculum
bone to maintain rigidity in the penis of some mammals
scrotum
contains testes outside of the body (lower temp)
testes
composed of highly coiled seminiferous tubules
seminiferous tubules
produce sperm
epididymis
highly coiled tube where sperm mature
ejaculation
process of getting sperm from the inside to the outside
path of sperm to outside the body
epididymis to muscular vas deferens to ejaculatory duct to urethra
semen
sperm mixed with the products from seminal vesicles, prostate gland, and bulbourethral glands
steps of spermatogonium
diploid stem cells within testes to primary spermatocytes (2n) to secondary spermatocytes (n x 2) to spermatids (n x 4) to sperm cells (n x 4)
GnRH
gonadotropin-releasing hormone; released from hypothalamus. stimulates pituarty to release LH and FSH
FSH
follicle-stimulating hormone from pituitary; tropic hormone
LH
luteinizing hormone from pituitary gland; tropic hormone
androgens
produced in male gonads like testosterone
estrogens
produced in female gonads, like estradiol and progesterone
hormonal control of spermatogenesis
GnRH leads to release of FSH and LH; FSH acts on sertoli cells to nourish developing sperm, LH acts on leydig cells to promote spermatogenesis
ovaries
female gonads; where ovum are produced
oocytes
partially developed eggs; 1-2 million follicles at birth but only about 500 mature
ovulation
release of ovum
corpus luteum
follicle becomes corpus luteum after ovulation; degrades without fertilization
oviducts
fallopian tubes, leads to uterus
uterus
womb; where egg implants after fertilization
endometrium
lining of uterus; many blood vessels to support developing fetus
vagina
muscular elastic chamber opens to the outside at the vulva
vulva
female external genitalia
labia majora
enclose the rest of vulva
labia minora
enclose cavity with vaginal opening and urethra
clitoris
located at top of labia minora, consists of erectile tissue
steps of oogenesis
oogonium (diploid stem cell) to primary oocyte (2n) to secondary oocyte (n + polar body) to fertilized egg (2n + polar body
fertilized egg
ovulation + sperm develops into 2n zygote
ovarian cycle
about 28 days, produces ovum. under control of same hormones as spermatogenesis
follicular phase (ovarian cycle)
growing follicle secretes increased estradiol
ovulation
maturing follicle ruptures and released secondary oocyte
luteal phase
follows ovulation; LH stimulates development of corpus luteum, secretion of estradiol and progesterone
menstrual cycle
prepares the uterus to support a fetus
proliferative phase of menstrual cycle
estradiol from follicles causes endometrium to thicken
secretory phase
after ovulation, estrogens stimulate development of uterine lining, including arteries and glands
menstrual flow phase
corpus luteum disintegrates, hormone levels drop and endometrium degrades, releasing blood
menopause
ovarian and uterine cycles end
24 hours past fertilization
first cleavage
2-3 days past fertilization
zygote reaches uterus
1 week past fertilization
blastocyst implants in endometrium
2-3 weeks past fertilization
embryo gets nutrients directly from endometrium
hCG
embryo produces hCG, can be detected in mother’s urine
pregnancy
one or more embryos in the uterus
placenta
forms from embryonic and maternal tissue; blood vessels from both exchange nutrients, gases, wastes, etc.
organogenesis
formation of organs; after 8 weeks of organogenesis embryo termed a fetus
labor
childbirth; led from interactions between estradiol, oxytocin and prostaglandins; dilation of the cervix and contractions of the uterus