• A Hormone is a chemical released by a cell or a
gland in one part of the body that sends out
messages that affect cells in other parts of the
• Hormones are released in a very small amount.
• Endocrine Hormones are secreted (released)
directly into the bloodstream, whereas Exocrine
Hormones (or ectohormones) are secreted
directly into a duct, and, from the duct, they flow
either into the bloodstream or from cell to cell by
diffusion in a process known as paracrine
• The Hypothalamus is a portion of the brain that
contains a number of small nuclei with a variety
• One of the most important functions of the
hypothalamus is to link the nervous system to the
endocrine system via the pituitary gland.
• It synthesizes and secretes certain
neurohormones, often called hypothalamic-
releasing hormones, and these in turn stimulate
or inhibit the secretion of pituitary hormones.
• The hypothalamus controls body temperature,
hunger, thirst, fatigue, sleep, and circadian cycles.
• Pituitary Gland, is an endocrine gland about the size
of a pea and weighing 0.5 gm.
• Also called “Master Gland”.
• It secretes variety of hormones, which stimulate the
other endocrine glands to secrete their own
• Pituitary gland functions under the control of
• The pituitary gland is functionally linked to the
hypothalamus by the Pituitary Stalk
• Anterior Pituitary Gland synthesizes and releases
- Follicle Stimulating Hormone (FSH)
- Lutenizing Hormone (LH)
• Both of these hormones are released under
influence of Gonadotropin Releasing Hormone
(GnRH) from Hypothalamus
• Also called FSH
• FSH regulates the development, growth, pubertal
maturation, and reproductive processes of the body.
• FSH and Luteinizing Hormone (LH) act synergistically in
• In females, FSH initiates follicular growth.
• Decline in FSH levels during late follicular phase seems
to be critical in selecting only the most advanced
follicle to proceed to ovulation.
• At the end of the luteal phase, there is a slight rise in
FSH that seems to be of importance to start the next
FOLLICLE STIMULATING HORMONE
• Also called LH or Lutropin
• In females, an acute rise of LH called the LH surge
triggers ovulation and development of the
• LH is necessary to maintain luteal function for the
first two weeks.
• In case of a pregnancy luteal function will be
further maintained by the action of hCG (a
hormone very similar to LH) from the newly
• The three major naturally occurring estrogens in women
are estrone (E1), Estradiol (E2), and Estriol (E3).
• Estradiol (E2) is the predominant form in nonpregnant
females, Estrone (E1) is produced during menopause, and
Estriol (E3) is the primary estrogen of pregnancy.
• Estradiol levels vary through the menstrual cycle, with
levels highest just before ovulation.
• Estrogens are produced primarily by developing follicles in
• Luteinizing Hormone (LH) stimulates the production of
estrogen in the ovaries.
• Promote formation of female secondary sex
• Reduce muscle mass
• Stimulate endometrial growth
• Increase uterine growth
• Increase vaginal lubrication
• Thicken the vaginal wall
• Maintenance of vessel and skin
• Reduce bone resorption
• Increase bone formation
Role of ESTROGENS
• "Pro" means "for" and “gesterone” means "gestation".
• Gestation is the carrying of an embryo or fetus inside
• Progesterone is sometimes called the “Hormone of
• Progesterone converts the Endometrium to its
secretory stage to prepare the uterus for implantation.
At the same time Progesterone affects the Vaginal
Epithelium and Cervical Mucus, making it thick and
impenetrable to sperm.
• If the egg is fertilized (Pregnancy occurs), the
Corpus Luteum will begin receiving hCG from the
embryo. hCG tells the Corpus Luteum to keep
• If pregnancy does not occur, Progesterone levels
will decrease, leading to Menstruation. Normal
Menstrual Bleeding is Progesterone-withdrawal
• also called hCG
• hCG is a glycoprotein hormone produced in
pregnancy that is made by the developing
embryo after conception and later by the
syncytiotrophoblast (part of the placenta).
• Its role is to prevent the disintegration of the
corpus luteum of the ovary and thereby maintain
progesterone production that is critical for a
• Early pregnancy testing, in general, is based on
the detection of hCG.
HUMAN CHORIONIC GONADOTROPIN
• Menstruation is the periodic discharge of blood
and sloughed endometrium (collectively called
menses or menstrual flow) through the vagina.
• Menstruation occurs throughout a woman's
reproductive life in the absence of pregnancy.
• The average Menstrual Cycle length is 28 days
(usual range, about 25 to 36 days).
• Average duration of menses is 5 (± 2) days.
• Blood loss per cycle averages 30 mL (normal
range, 13 to 80 mL) and is usually greatest on the
• Menarche is the first menstrual cycle, or first
menstrual bleeding, in female human beings.
• The average age of menarche is 11.75 years.
• Menopause is the permanent cessation of
• Menopause typically (but not always) occurs in
women during their late 40s or early 50s, and
signals the end of the fertile phase of a woman's
• The Menstrual Cycle can be divided into 3
- Follicular (Preovulatory) Phase
- Ovulatory Phase
- Luteal (Postovulatory) Phase
During this Phase ovary also
secretes increasing level of
Estrogen, to initiate
Pituitary gland produces FSH
(Follicular Stimulating Hormone)
FSH act on ovary for prompt
development of several follicles
(Each Follicle Contains Egg)
During this phase one follicle
Hypothalamus releases GnRF which stimulates
release of LH and FSH from Anterior Pituatary
Lasts for 16 to 32 hours
Phase begins when the level of LH surges.
LH stimulates dominant follicle to bulge from the
surface of ovary and finally rupture, releasing the Egg.
Egg travel to Fallopian Tube. This is the time when the
women is most likely to become Pregnant. The Egg can be
fertilized for only up to about 12 hours after its release.
Luteal Phase, Day 15-28
After releasing Egg this empty Follicle develops the structure
called Corpus Luteum (CL)
CL secrets increasing amount of Progesterone. CL prepares
Uterus in case fertilization occurs.
Progesterone causes the Endometrium to thicken
If Egg is Fertilized If Egg is not Fertilized
CL destroys after 14 days
an new Menstrual Cycle
The embryo produces Human Chorionic
Gonadotropin (hCG) which will be detected by
CL and this Human Chorionic Gonadotropin
maintains CL and its Progesterone secretion.
The egg moves to the uterus and attaches itself to the
endometrium about six or seven days after ovulation,
where it begins to develop into a fetus.
Amenorrhea is the absence of a menstrual period in a
woman of reproductive age.
Primary Amenorrhea is the absence of menstruation in
a woman by the age of 16.
Secondary Amenorrhea is where an established
menstruation has ceased—for 3 months in a woman
with a history of regular cyclic bleeding, or 9 months in
a woman with a history of irregular periods.
Dysmenorrhea is a gynecological medical condition
characterized by severe uterine pain during
Menorrhagia is an unusually heavy and prolonged
menstrual period at regular intervals.
A blood loss of greater than 80 ml or lasting longer than
7 days constitutes menorrhagia
Hypomenorrhea is extremely light menstrual blood flow
Metrorrhagia is uterine bleeding at frequent, irregular
intervals, particularly between the expected menstrual
Menometrorrhagia is a condition in which prolonged or
excessive uterine bleeding occurs irregularly and more
frequently than normal.
Polymenorrhea is the medical term for cycles with intervals of
21 days or fewer.
Oligomenorrhea is infrequent (or very light) menstruation.
More strictly, it is menstrual periods occurring at intervals of
greater than 35 days.