lecture 10: reproductive system Flashcards
name the parts of the male reproductive system (external)
penis
scrotum
describe the penis
contains urethra (passageway for sperm and semen - urinary (excretory) and reproductive systems)
consists mostly of erectile tissue that fills with blood during an erection
describe the scrotum
pouch of skin containing testes
allows testes to hang outside abdominal cavity asa lower temp is needed for sperm production
name the internal structures of the male reproductive system
testes
epididymis
vas deferens
ejaculatory duct
describe the testes
site of sperm production (in seminiferous tubules)
describe the epididymis
sperm storage
maturation (sperm becomes mobile)
carries sperm from testes to vas deferens
describe the vas deferens
passageway for sperm from epididymis to ejaculatory duct
describe the ejaculatory duct
connects vas deferens to urethra
name the accessory glands of the male reproductive system
seminal vesicles
prostate gland
bulbourethral glands
describe seminal vesicles
produce 60% of seminal fluid
(mucus, fructose, ascorbic acid, coagulating enzyme and prostaglandins)
describe prostate gland
produces prostatic fluid that is added to semen
(citrate and anticoagulant enzymes)
describe bulbourethral glands
secretes clear mucus that neutralizes acidity of urine prior to ejaculation (pre-ejaculate)
may carry some sperm (pull out method does not work)
describe testes (more detail)
male gonads
contain seminiferous tubules - site of sperm production
leydig cells (scattered between seminiferous tubules) - produce testosterone
describe sperm
contains haploid nucleus (n= 23 chromosomes)
acrosome at tip of head contains enzymes that penetrate the egg
what powers flagellum (in sperm)
large number of mitochondria
makes sperm very motile
describe semen
seminal fluid + sperm
how many sperm in each ejaculation
100-650 million sperm
describe pathway of sperm
testes (seminiferous tubules) –> epididymis –> vas deferens –> ejaculatory duct (seminal veicles) –> urethra (prostate and bulbourethral glands)
what is a vasectomy
cutting vas deferens in scrotum
no sperm in ejaculate
name the parts of the female reproductive system (external)
vulva = labia and clitoris
describe vulva
external female sex organs
describe labia
major and minor
folds of skin and adipose tissue
covers and protects vaginal opening and clitoris
describe clitoris
structure located towards the front of vulva
high density of sensory receptors
similar structure to penis
name parts of female reproductive system (internal)
fallopian tubes
uterus
vagina
cervix
ovaries
describe fallopian tubes
site of fertilization
conducts ovum to uterus
describe uterus
houses developing embryo
describe vagina
thin walled canal
functions as passageway for sperm and birth canal
describe cervix
connects uterus to vagina
describe ovaries (gen)
maturation of ovum
describe ovaries (more specific)
female gonads
flank uterus
located in abdominal cavity
each ovary contains follicles
describe follicles
nourish egg and protect developing egg/ovum
how many follicles are females born with
~1 million but ~ 300 thousand remain at puberty and only a few hundred will release eggs during reproductive years
what do prostaglandins do (seminal vesicles)
thins cervical mucus
stimulates uterine contractions
what is spermatozoa
sperm = male gametes
what is seminal fluid
secretions from seminal vesicles, prostate and bulbourethral glands
what is endometrium
uterine lining
what happens during menstrual cycle
one follicle matures and releases its ovum during ovulation (~ day 14)
after ovulation (menstrual cycle)
remaining follicle become corpus luteum
corpus luteum produces (menstrual cycle)
estrogens and progesterone to maintain endometrium during pregnancy
if pregnancy does not occur (menstrual cycle)
corpus luteum degrades and uterine lining is shed
what is estradiol
primary estrogen in females
how many phases of menstrual cycle
3
name the phases of menstrual cycle and the amount of days each phase is
1 - follicular phase = days 1-14
2 - ovulation = day 14
3 - luteal phase = days 14-28
describe follicular phase (menstrual cycle)
several follicles are stimulated to grow
triggered by FSH (most important for early development of follicles)
only one follicle fully matures
describe ovulation (menstrual cycle)
surge in LH causes follicle to rupture and expel secondary oocyte into fallopian tubes
describe luteal phase (menstrual cycle)
remainder of follicle becomes corpus luteum
name the hormones that regulate the menstrual cycle and where they come from
gonadotropin releasing hormone - hypothalamus
FSH - anterior pituitary
LH anterior pituitary
estrogen and progesterone - follicle and corpus luteum
describe function of gonadotropin releasing hormone (menstrual cycle)
stimulates release of small amounts of FSH and LH
what is gonadotropin releasing hormone stimulated and inhibited by (menstrual cycle)
stimulates by high levels of estrogen
inhibited by estrogen + progesterone
describe function of FSH (menstrual cycle)
stimulates growth of immature follicles
what is FSH inhibited by (menstrual cycle)
low levels of estrogen
describe function of LH (menstrual cycle)
increased estrogen secretion from follicle causes a surge in production of LH –> triggers ovulation
what is LH inhibited by (menstrual cycle)
low levels of estrogen
explain positive feedback of menstrual cycle
GnRH = stimulated by high levels of estrogen
causes LH surge on day 14 for ovulation to occur
explain negative feedback of menstrual cycle
prevents maturation of new follicle before beginning of next cycle
prevents ovulation if pregnancy occurs
state ENTIRE summary of menstrual cycle
- Hypothalamus secretes GnRH which stimulates the anterior pituitary to produce FSH and LH
- FSH and LH stimulate the growth of follicles in the ovary. Eventually one follicle becomes dominant.
- Estrogen levels gradually increase as follicle grows
- Estrogen levels become high enough to stimulate the release of GnRH from the hypothalamus.
- LH and FSH levels rapidly increase. LH levels increase much more!
- Peak in LH causes ovulation! (~day 14)
- Empty follicle becomes corpus luteum. Corpus luteum produces estrogen and progesterone to thicken and maintain endometrium
- Corpus luteum degenerates if pregnancy does not occur and endometrium is shed.
how does contraceptive pill work
made of estrogen and progesterone
inhibits release of GnRH = no LH released = NO OVULATION
describe first step of fertilization and implantation
ovum fertilized - in fallopian tube
undergoes several rounds of cell division as it moves towards uterus
describe second step of fertilization and implantation
implantation in uterus happens
~7 days after fertilization
how long is a human pregnancy
~266 days
describe hCG
human gonadotropin hormone is secreted by embryo
stimulates production of progesterone by corpus luteum during first 3 months of pregnancy
what happens in 2nd trimester of pregnancy
3-6 months - the placenta is developed enough and takes over the production of progesterone (to maintain endometrium) from corpus luteum
what does the placenta allow for
exchange between mother and fetal circulatory systems
describe oogenesis
takes place in ovaries
at birth - ovaries contain all primary oocytes it will ever have (~1 mil)
after puberty - one follicle matures every 28 days (ovarian/menstrual cycle)
describe cell division of oogensis
primary oocyte (2n=46 chromosomes) –> secondary oocyte (n=23 chromosomes) –> ovum (n=23 chromosomes) *before becomes ovum, ovulation fertilization - fertilization must occur for completion of oogenesis
describe spermatogenesis
takes place in seminiferous tubules
occurs continuously in males after puberty
sertoli cells support developing sperm
describe cell division of spermatogenesis
primary spermatocyte (2n=46 chromosomes) –> sperm cell (n=23 chromosomes) x 4
which hormones control spermatogenesis
GnRH
FSH
LH
testosterone
describe what GnRH does (hormonal control of spermatogenesis)
from hypothalamus
stimulates release of FSH and LH from anterior pituitary
describe what FSH does (hormonal control of spermatogenesis)
stimulates spermatogenesis
describe what LH does (hormonal control of spermatogenesis)
stimulates release of testosterone from leydig cells
describe what testosterone does (hormonal control of spermatogenesis)
stimulates spermatogenesis
what controls negative feedback of spermatogenesis
testosterone and inhibin
describe testosterone (negative feedback of spermatogenesis)
inhibits release of FSH/LH
inhibits release of GnRH
describe inhibin (negative feedback of spermatogenesis)
released in response to FSH
inhibits release of FSH/LH
how long is menstrual cycle
~ 28 days
what happens if pregnancy occurs (luteal phase)
corpus luteum sustains pregnancy until placenta takes over at around 3 months
what happens if pregnancy does not occur (luteal phase)
corpus luteum degenerates
without estrogen/progesterone to maintain endometrium –> it is shed (menstrual bleeding)
describe function of estrogens and progesterone (menstrual cycle)
growing follicle produces estrogen (causes LH surge)
corpus luteum produces estrogen and progesterone
stimulates growth and maintenance of endometrium
