The Reproductive System

Question 1

penis

Answer 1

deliver sperm to the female reproductive
tract

Is composed of three cylindrical bodies of erectile tissue called the corpus spongiosum and corpora cavernosa

Question 2

scrotum

Answer 2

Houses the testis
Is composed of the dartos and cremaster muscles which maintain optimal temperature for the production of viable sperm

Question 3

testes

Answer 3

seminiferous tubules
factory for sperm production
is surrounded by smooth
muscle to help squeeze
sperm into the epididymis

Question 4

sustentocytes

Answer 4

produce testicular fluid,
provide developing sperm
with nutrients and produces
androgen binding protein

Question 5

Interstitial cell

Answer 5

located in the testes but outside of
seminiferous tubules and
produce testosterone

Question 6

Epididymis

Answer 6

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

Question 7

ductus deferens

Answer 7

tube that runs from the scrotal sac to the urethra

Question 8

Seminal vesicles

Answer 8

attach to the ductus deferens
Produce and release seminal fluid
enhance sperm motility and their ability to fertilise an ovum:
fructose
prostaglandins
fibrinogen

Question 9

ejaculatory duct

Answer 9

seminal vesicles join the ductus deferens
Transports sperm through the prostate gland to the urethra

Question 10

prostate gland

Answer 10

• 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)

Question 11

urethra

Answer 11

prostate and down to the tip of
the penis
* functions to convey both urine
and semen

Question 12

bulbourethral glands

Answer 12

inferior to the prostate on
either side of the urethra
produce a thick mucus which
lubricates the glans penis and
neutralises traces of urine

Question 13

Spermatogenesis

Answer 13

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

Question 14

GnRH

Answer 14

in hypothalamus
releases FSH & LH from the anterior
pituitary
FSH stimulates sustentocytes produce ABP which concentrates testosterone
LH stimulates interstitial cells to produce testosterone

Question 15

testosterone

Answer 15

stimulates spermatogenesis
growth of reproductive ducts and glands
size of penis
maintain erection and obtain
ejaculation

Question 16

The vagina

Answer 16

child birth
Provides a passageway for menstrual fluids
Receives the penis during sex
acidic environment= no infection
muscular and elastic= stretch and recoil

Question 17

uterus

Answer 17

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.

Question 18

endometrium

Answer 18

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

Question 19

Uterine tubes

Answer 19

site of fertilisation

Question 20

ovaries

Answer 20

Produces and secretes oestrogen and progesterone
Produces and ovulates secondary oocytes

Question 21

fimbriae

Answer 21

Has ciliated finger-like projections. These assist the oocytes journey into the uterine tube

Question 22

Oogenesis

Answer 22

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

Question 23

Ovarian cycle: Follicular Phase

Answer 23

follicle grows due to FSH
granulosa cells formed around oocyte:
provide nourishment while it enlarges
Thecal cells and granulosa cells produce
oestrogens

Question 24

Ovulation

Answer 24

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

Question 25

Hormonal regulation of follicular phase

Answer 25

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

Question 26

Ovarian cycle: Luteal Phase

Answer 26

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

Question 27

if fertilisation does not occur:

Answer 27

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

Question 28

Hormonal regulation of Luteal phase

Answer 28

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

Question 29

The uterine (menstrual) cycle

Answer 29

* 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

Question 30

Fertilisation

Answer 30

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

Question 31

Entry of sperm DNA causes increased calcium levels in the oocyte

Answer 31

triggers the cortical reaction which destroys sperm receptors and hardens the zona pellucida preventing further entry of sperm. This blocks polyspermy

Question 32

Embryonic Development

Answer 32

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

Question 33

Implantation of blastocyst

Answer 33

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

Question 34

implantation is successful

Answer 34

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