Reproduction is like an orchestra
- and the reproductive organs need to be synchronised to perform at just
the right time for them to work properly. It is the fertility hormones
which play the conductor's role.
Hormones are chemicals the body makes
to carry messages from one part of the body to another. There are two major
female hormones - estrogen and progesterone - which are produced by the
ovaries.
The cycle of ovarian hormone production
has two phases. In the first half called the follicular phase, estrogen
plays a dominant role. During this phase the egg matures inside the ovary
in its follicle. The egg; the surrounding cells (which nurture the egg
and are called granulosa cells and theca cells); and the fluid (called
follicular fluid) which accumulates in progressively larger amounts during
this phase, is called a follicle. The follicle secretes a large amount
of estrogen (produced by the granulosa cells) into the bloodstream, and
the estrogen circulates to the uterus where it stimulates the endometrium
to thicken.
The second phase of hormone production
begins at ovulation, midway through the cycle, when the follicle changes
into the corpus luteum. This produces estrogen; and also large quantities
of progesterone throughout the second half of the cycle. Travelling through
the bloodstream to the uterus, progesterone complements the work begun
by estrogen by stimulating the endometrium to mature and making it possible
for a fertilized egg to implant in it. In case pregnancy does not occur,
production of estrogen and progesterone falls 10 to 14 days after ovulation
as the corpus luteum dies, and the endometrium is shed from the body as
the menstrual period.
How is the release of hormones regulated
by the body? This is a complex self-regulating system, which uses negative
feedback control loops, much like a thermostat for an oven does. As the
temperature increases, the thermostat shuts off the heater to reduce its
heat output. When the temperature falls below the thermostat's setting,
the thermostat signals the heater to turn up the heat again, thus maintaining
the desired temperature. A similar signaling relationship exists between
the pituitary gland and the ovaries in women; and the testes in men. For
example, as the concentration of gonadotropins in the blood rises, this
signals the woman's ovaries to increase hormonal output of estrogen. In
turn, when the blood levels of estrogen rise, the pituitary gland slows
its release of gonadotropins, thus maintaining the desired equilibrium.
Name:
Seeker
Country: Barbados
the production of eggs are controlled by hormones. A female is born with millions of eggs which eventually die during each menstrual cycle. So the role of hormones is very important.
Name:
Petra
Country: Costa Rica
how do hormones regulate the productions of eggs? what happens when an egg is released?
Name:
Retto
Country: El Salvador
what are the roles of different female hormones? what will happen if any one of the hormones is malfunctioning? Please explain
