Hormones and Sexuality
The Endocrine System
The Menstrual Cycle
Length of the Menstrual Cycle
Menstrual Synchrony and Pheromones
Attitudes About Menstruation: Historical
Perspectives
Attitudes About Menstruation Today
Menstrual Problems
Regulation of Male Hormones
Hormones and Sexual Desire
The Endocrine System
• Hormones play a crucial role in both men and
women. They are important for growth,
metabolism, water retention, reaction to stress, and
many other functions.
• Hormones are chemical substances that are
released into our bloodstream by ductless glands.
They are carried in the blood to other parts of the
body where they exert their effects. Hormones
released by one gland often cause another gland to
release its own hormones. This network of
ductless glands is called the endocrine system.
• The testicles and the ovaries are part of the
endocrine system. The testicles manufacture and
release testosterone, and the ovaries produce
progesterone and estrogen.
• The pituitary gland releases eight different
hormones into the bloodstream. Two of these
have their effect on the ovaries and testicles, and
are thus called gonadotropins.
• In women, follicle-stimulating hormone
stimulates the maturation of a follicle in the
ovaries.
• A second pituitary gonadotropin hormone is called
luteinizing hormone. In women, LH triggers
ovulation. In men, it stimulates the testicles to
produce male hormones.
The Menstrual Cycle
• An ovum is surrounded by other cells within a thin
capsule of tissue to form a follicle.
• At birth, each ovary has about 300,000 to 400,000
immature follicles, and the ovaries do not produce
any new follicles during a woman’s lifetime.
• The average length of an adult human menstrual
cycle is about 28 days.
Preovulatory Phase (Day 5 to 13)
• This phase is also referred to as the follicular or
proliferative phase.
Ovulation (Day 14)
• The LH surge signals the onset of ovulation within
12 to 24 hours.
• At ovulation, the follicle ruptures and the ripe
ovum is expelled into the abdominal cavity, where
it will soon be picked up by a Fallopian tube.
Postovulatory Phase (Days 15 to 28)
• If the egg is fertilized by a sperm, it continues its
trip through the Fallopian tube and implants itself
in the endometrium.
Menstruation (Days 1 to 14)
• With the decline in levels of estrogen and
progesterone, there is loss of the hormones that
were responsible for the development and
maintenance of the endometrium.
Length of the Menstrual Cycle
• Most women have cycles that vary in length by 8
days or more.
Menstrual Synchrony and
Pheromones
• They were attracted by natural body scents called
pheromones. Pheromones are defined as “a
substance secreted by an animal to the outside of
that individual which is then received by another
individual…of the same species, which then elicits
some behavioral or development response in the
latter.”
Attitudes About Menstruation:
Historical Perspectives
• The biblical Hebrews regarded a menstruating
woman as “unclean” or “impure,” and believed
that she could transfer her condition of
uncleanliness to a man during sexual intercourse.
Attitudes About Menstruation
Today
• Myths that women should avoid bathing,
swimming, and exercise during menstruation are
common.
• Bathing, washing their hair and swimming are not
the only things many women do without during
menstruation.
• The discharge consists of nothing more than some
sloughed off endometrial tissue, mucus, and a
small amount of blood.
Amenorrhea
• Amenorrhea refers to the absence of menstruation
for 6 months or longer. Oligomenorrhea is the
absence of menstruation for shorter intervals, or
unevenly spaced menstrual periods.
• Girls with high body fat levels generally start
menstruating at a younger age than girls with low
levels of body fat.
• Amenorrhea is common among female athletes.
Women with the eating disorder anorexia nervosa
are often considerable under weight, and as a
result rarely menstruate.
• While poor health can result in amenorrhea,
amenorrhea can also affect a woman’s health.
• For example, the low levels of estrogen usually
associated with amenorrhea often result in longterm problems such as osteoporosis and
cardiovascular disease.
• Thus, a premenopausal woman who is not
menstruating regularly should consult a physician.
Premenstrual Syndrome (PMS)
• PMS refers to a group of physical and/or
emotional changes that many women experience
in the last 3 to 14 days before the start of their
menstrual period.
• Only about 75% of women with regular menstrual
cycles have some symptoms.
• To be diagnosed with PMDD, a woman’s
symptoms must “markedly interfere” with social
relations, work, or education, and include at least
one of the following symptoms: markedly
depressed mood, marked anxiety or tension,
persistent and marked irritability or anger, or
“marked affective lability” (extreme changes in
mood, such as sudden sadness).
• It is estimated that 3 to 8% of all women in their
reproductive years have PMDD.
Dysmenorrhea
• Symptoms can include backaches, headaches, a
feeling of being bloated, and nausea.
Endometriosis
• Endometriosis refers to a condition in which the
endometrial tissue also grows outside the uterus.
Toxic Shock Syndrome (TSS)
• TSS is caused by toxins produced by a bacterium.
Regulation of Male Hormones
• In men, the hypothalamus, pituitary gland, and
testicles operate in a feedback loop much like the
feedback loop in women.
Hormones and Sexual Desire
• Research on sex and hormones relies heavily on
two types of studies: those investigating the effects
of administering hormones and those investigating
the effects of a loss of hormones.
• After puberty in boys, 6 to 8 milligrams of
testosterone are produced every day, and among
very young adolescent boys, sexual activity
increases as testosterone levels increase.
• There is a decline in testosterone production as a
man grows older, but men who are sexually active
often have high testosterone levels.
• Hypogonadal men show very little interest in sex.
• In some parts of the world, men who were once
used as harem attendants were forced to have their
testicles removed so that they would not be
interested in the women they were supposed to
protect.
• In many cases this worked, especially if the men
were not yet sexually experienced at the time of
castration.
• However, there were also stories of some eunuchs
having the time of their lives, like roosters
guarding a hen house.
• Modern studies of castrated men show, however,
that sex drive and behavior are drastically or
completely suppressed in a high percentage of
cases.
• In Europe and in the United States, some judges
now offer male sex offenders a choice between
prison and chemical castration with antiandrogen
drug called DepoProvera. This drug and others
like it severely reduce testosterone production, and
often reduce interest in sex.
• What about women? The loss of estrogen and
progesterone at menopause does not reduce sexual
desire in most women. In those postmenopausal
women who do show a decrease, estrogen
replacement therapy alone generally has no effect.