The Reproductive System Flashcards
penis
deliver sperm to the female reproductive
tract
Is composed of three cylindrical bodies of erectile tissue called the corpus spongiosum and corpora cavernosa
scrotum
Houses the testis
Is composed of the dartos and cremaster muscles which maintain optimal temperature for the production of viable sperm
testes
seminiferous tubules
factory for sperm production
is surrounded by smooth
muscle to help squeeze
sperm into the epididymis
sustentocytes
produce testicular fluid,
provide developing sperm
with nutrients and produces
androgen binding protein
Interstitial cell
located in the testes but outside of
seminiferous tubules and
produce testosterone
Epididymis
Stores, nourishes and protects spermatozoa
facilitates functional maturation
recycles damaged sperm
ejaculates into ductus
deferens
surrounds the posterior edge of the testes
and is a series of coiled tubes
ductus deferens
tube that runs from the scrotal sac to the urethra
Seminal vesicles
attach to the ductus deferens
Produce and release seminal fluid
enhance sperm motility and their ability to fertilise an ovum:
fructose
prostaglandins
fibrinogen
ejaculatory duct
seminal vesicles join the ductus deferens
Transports sperm through the prostate gland to the urethra
prostate gland
- a doughnut shaped gland that surrounds the urethra
citrate (nutrients), a number of enzymes that breakdown seminal clot e.g.
fibrinolysin and PSA (a protein also found in the blood and used
to detect prostate cancer), and
seminalplasmin (antibiotic properties)
urethra
prostate and down to the tip of
the penis
* functions to convey both urine
and semen
bulbourethral glands
inferior to the prostate on
either side of the urethra
produce a thick mucus which
lubricates the glans penis and
neutralises traces of urine
Spermatogenesis
mitosis of spermatogonia followed by meiosis to produces four spermatids half
chromosomes
spermatids - small non-motile cells
spermatids lose excess cytoplasm,
form a tail
spermatozoa break away from
sustentocytes into the lumen of the
seminiferous tubule
spermatozoa move into the
epididymis
GnRH
in hypothalamus
releases FSH & LH from the anterior
pituitary
FSH stimulates sustentocytes produce ABP which concentrates testosterone
LH stimulates interstitial cells to produce testosterone
testosterone
stimulates spermatogenesis
growth of reproductive ducts and glands
size of penis
maintain erection and obtain
ejaculation
The vagina
child birth
Provides a passageway for menstrual fluids
Receives the penis during sex
acidic environment= no infection
muscular and elastic= stretch and recoil
uterus
Provides an environment for the development of offspring.
Perimetrium – outer layer.
Myometrium – contracts during childbirth to expel the fetus.
Endometrium – contains the functional layer which is shed during menses. This is the site of implantation.
endometrium
functional layer: undergoes
cyclic changes due to ovarian
hormones and is shed during
menstruation
basal layer: unresponsive to
ovarian hormones, regenerates
functional layer following
menstruation
Uterine tubes
site of fertilisation
ovaries
Produces and secretes oestrogen and progesterone
Produces and ovulates secondary oocytes
fimbriae
Has ciliated finger-like projections. These assist the oocytes journey into the uterine tube
Oogenesis
occurs in the ovaries
* begins in the fetal period
* oocytes stay in a suspended state until puberty
* a small number of primary oocytes are recruited each
month – but only one is selected to go through meiosis
to form the mature oocyte
Ovarian cycle: Follicular Phase
follicle grows due to FSH
granulosa cells formed around oocyte:
provide nourishment while it enlarges
Thecal cells and granulosa cells produce
oestrogens
Ovulation
a number of follicles are being prepared
within the ovary at any one time
* the bulging follicle eventually ruptures the wall of the ovary and the oocyte is
released
* ovulation triggered by increases in LH
(and FSH)
* occurs around 14d of the ovarian cycle
Hormonal regulation of follicular phase
GnRH released by the
hypothalamus stimulates the
anterior pituitary gland to release
FSH and LH
FSH stimulates follicle maturation
FSH stimulates granulosa and Thecal
cells to secrete oestrogens
.Increasing levels of oestrogens
stimulate a surge in LH secretion
which triggers ovulation and
development of corpus luteum
Ovarian cycle: Luteal Phase
period of CL activity
* ruptured follicular cells
remaining after ovulation are
now called CL
LH is the hormone responsible
for transforming the ruptured
follicle into a CL
* CL produces progesterone to maintain
the functional layer of the endometrium
if fertilisation does not occur:
CL degenerate to corpus albicans
progesterone and oestrogen levels
drop
triggers shedding of endometrial
lining menstruation
decreased progesterone and
oestrogen stimulate release of
GnRH, LH an FSH to start follicular
phase
Hormonal regulation of Luteal phase
LH surge transforms the ruptured follicle into the CL
The CL produces large amount of progesterone and
oestrogen
If fertilisation does not occur the CL degenerates,
hormone levels decline and the cycle begins again
The uterine (menstrual) cycle
- Menstrual phase: shedding of the functional layer of the
endometrium
oestrogen and progesterone are low
Proliferative phase: rebuilding of the functional layer of the endometrium
mucus becomes less viscous and sticky to allow entry of sperm
oestrogen stimulates the phase
Secretory phase: progesterone (& oestrogens) from CL stimulates
endometrium preparing for implantation
Fertilisation
must undergo Capacitation= thins the plasma membrane overlying the
acrosome
Sperm weave through the corona radiata.
Sperm bind to zona pellucida
rise in calcium levels in the sperm
complete breakdown of the acrosomal
membranes
release of the acrosomal enzymes called
the acrosomal reaction=digest holes in the zona pellucida
sperm binds to special receptors on the
oocyte membrane
The sperm and oocyte membranes fuse
Entry of sperm DNA causes increased calcium levels in the oocyte
triggers the cortical reaction which
destroys sperm receptors and hardens the zona pellucida preventing further entry of sperm.
This blocks polyspermy
Embryonic Development
zygote undergoes cell division
fluid filled cavity forms= zona pelludica starts to break down, blastocyst and
ready for implantation
The blastocyst consists of:
1. an inner cell mass= embryo
2. a fluid filled cavity
3. a layer of trophoblast cells= placenta
Implantation of blastocyst
when the endometrium is most
receptive as there are well developed blood supply and uterine glands producing lots of glycogen-rich mucus
blastocyst buries itself within the endometrium, the endometrial cells cover the blastocyst
implantation is successful
complete just before menstruation as
shedding of the functional
layer would lead to loss of the implanted embryo
menstruation is prevented by the embryo signalling to the CL to continue to produce progesterone and oestrogen
hCG produced by the trophoblast cells
hCG bypasses hypothalamic and pituitary control of the ovarian cycle
