king, human sexuality today, 5/e (c) 2005 by prentice hall 1 chapter 3 hormones and sexuality for...

King, Human Sexuality Today, 5/e (c) 2005 by Prentice Hall1

Chapter 3Hormones and Sexuality

For use with text,

Human Sexuality Today,

5th edition.

Bruce M. King

Slides by Callista Lee


What are hormones?

Hormones are chemical substances secreted by the ductless glands of the Endocrine System directly into the bloodstream which carries them to other parts of the body where they exert their influence on other glands or target organs.

The pituitary gland, located just beneath the brain’s hypothalamus is part of the Endocrine System.


Brain – Pituitary – Gonad feedback loop in women

Hormones produced by the gonads (the ovaries in women) are released into the bloodstream and are “read” by the pituitary gland which will alter its output of FSH and LH in response.


Reproductive hormones

Follicle-stimulating hormone (FSH) governs the production of ova in women and sperm in men. FSH is produced by the pituitary gland.

Luteinizing hormone (LH) triggers ovulation in women and the production of androgens (male hormones) in men. LH is also produced by the pituitary gland.

Both FSH and LH are under the control of gonadotropin-releasing hormone (GnRH) which is produced in the brain’s hypothalamus.


The menstrual cycle – its all about eggs

Each ovum (egg) is surrounded by cells which form a protective “follicle.”

At birth, each ovary has about 300,000 to 400,000 primordial (immature) follicles.

Each month about 1000 follicles begin but never complete the maturation process.

At puberty only about 200,000 follicles/ova remain and some will now complete the maturation process each menstrual cycle.


Changes within the ovaries


Menstruation

Menstruation actually takes place at the end of the menstrual cycle, after a mature ovum has been released (ovulation) but has failed to become fertilized by sperm.

The blood-rich endometrial lining of the uterus that had thickened in anticipation of a pregnancy sloughs off (menstruation) while other follicles in the ovaries begin the maturation process for the next cycle.


Myth of the 28-day cycle

28 days is only the statistically average length of an adult human woman’s menstrual cycle.

Consistent 28-day cycles are not very common. Variance between and within individuals is to be expected.

What we refer to as “Day 1” of the cycle is actually the first day of menstrual bleeding (menstruation) – at the end of the process.


Hormonal, ovarian and uterine changes during a 28-day cycle

Since your face is not on the cover of this textbook, don’t expect your cycle to look exactly like this one each month.

Allow for differences from month to month and between individuals.


Menstrual Cycle Days 5 - 13Preovulatory Phase

In this follicular or proliferative phase the pituitary secretes relatively high levels of FSH.

The growing follicle becomes a temporary endocrine gland, secreting increasing amounts of estrogen which inhibits FSH production in the pituitary.

When estrogen levels reach their peak, the pituitary releases a surge of LH.


Menstrual Cycle Day 14Ovulation

Again, day 14 is only an average; ovulation occurs anywhere from 12 – 16 days before the next menstrual flow.

The LH surge signals the onset of ovulation within 12 to 24 hours.

The Graafian (mature) follicle has moved to the surface of the ovary where the follicle will rupture, expelling the ripe ovum into the abdominal cavity.


Menstrual Cycle Days 15 - 28 Postovulatory Phase

This phase is also called the luteal or secretory phase because the cells of the follicle remain in the ovary, renamed the “corpus luteum,” where they will produce large amounts of progesterone.

Progesterone inhibits release of LH from the pituitary gland and further prepares the endometrial lining of the uterus to receive a fertilized egg.


Menstrual Cycle Days 1 to 4 Menstruation

In most cycles fertilization and implantation do not occur. The corpus luteum deteriorates and both progesterone and estrogen levels decline.

This decline in the hormones needed to maintain the endometrium leads to the degeneration of the endometrial lining which is sloughed off and shed over a 3 to 6 day period along with blood and cervical mucus.


Pheromones

Pheromones are chemical substances secreted externally by animals that convey information to and produce specific responses in members of the same species.

For example, when a female cat “goes into heat” male cats will pick up her scent and become sexually aroused.


Menstrual Synchrony

Women who live together and are regularly exposed to the pheromones (detected non-consciously) in each other’s sweat often experience changes in the length of their individual menstrual cycles so that they become synchronized.

Women with abnormal cycles tend to develop more normal cycles when exposed to male sweat.


Aphrodisiac Colognes?

Although perfume makers have long been hopeful to develop an aphrodisiac based on human pheromones, there is not yet any evidence to suggest that human sexual desire and behavior is affected by natural body odors.

Even menstrual synchrony may be due to factors much more complex than simple exposure to the natural odors of others.


Menstrual versus Estrous Cycle

The monthly menstrual cycle allows humans many opportunities for procreation throughout the year.

Regular menstruation may also allow the body to rid itself of potentially harmful bacteria in the uterus on a regular basis.

Most animals experience an estrous discharge and sexual/reproductive receptivity just once or twice a year.


Historical Hebrew and Modern Jewish Attitudes

Biblical-age Hebrews regarded menstruating women as “impure” and forbid all contact with men for 7 days.

A ritual bath, the Niddah, was required before she could again leave her home and have any contact with men.

Orthodox Jews still adhere to these practices to a lesser degree.


Menstrual Taboos and Celebrations

In many cultures menstrual taboos emphasize the low status and inferiority of women (e.g., Hunter-gatherer societies such as the Havik Brahmins, Lele, Kolish peoples).

However, Japanese and many Native American peoples celebrate a girl’s first menstruation as a positive experience and entry into womanhood.


Current American Attitudes

Most Americans view menstruating women as less likeable, less agreeable, less clean and more irritable.

The large majority of Americans seldom initiate sex during menstruation.

Actually, there is nothing dirty or nasty about menstruation as it is a normal, healthy event.


Menstrual Problems – Amenorrhea

Amenorrhea is the absence of menstruation for 6 months or longer

Ogliomenorrhea is the absence of periods for shorter intervals and is common in the first few years following menarche (first menses)

Pituitary and ovarian problems Low levels of body fat, especially among

athletes or anorexics.


Menstrual Problems – Premenstrual Syndrome (PMS)

3 to 14 days prior to the menstrual period, during the postovulatory/luteal phase

Bloating, breast tenderness, abdominal swelling, swollen hands and feet, weight gain, constipation, and headaches

Depression, anxiety, tension, irritability and inability to concentrate

75% of women experience some symptoms


Menstrual Problems – PMS vs. PMDD

Most women who perceive themselves as having PMS are actually misattributing symptoms of stress, poor health and work problems.

Premenstrual Dysphoric Disorder (PMDD) occurs in 3 – 8% of women and includes much more severe symptoms which markedly interfere with their lives.


Causes and Treatments of PMS and PMDD

Normal levels of estrogen and progesterone may interact with brain chemicals such as serotonin to produce symptoms.

Antidepressant medications often reduce tension and irritability.

Physical symptoms are often relieved by combating water retention and improving diet and exercise.


Menstrual Problems –Dysmenorrhea

Painful abdominal cramping, backaches, headaches, feeling bloated and nausea

In 7 to 15% of women symptoms are severe, most commonly in women under age 25.

Causes include pelvic abnormalities, endometriosis and over production of prostaglandins.


Menstrual Problems – Endometriosis

Endometrial tissue also grows outside the uterus, often involving the Fallopian tubes, ovaries, external surface of the uterus, vagina and pelvic cavity.

At menstruation this abnormal tissue will slough off but the blood cannot drain normally, causing inflammation and scar tissue to form.

It is found in 25 – to 40% of women examined for infertility.


More on Menstrual Problems

Endometriosis is treated with hormone therapy, including birth control pills, and/or surgery.

Toxic Shock Syndrome (TSS) is caused by bacteria that cause flu-like symptoms.

85% of TSS cases are related to menstruation and many are linked to use of super-absorbent tampons.

TSS can lead to death if not treated properly.


Regulation of Male Hormones

The hypothalamus, pituitary gland and testicles operate in a feedback loop.

GnRH causes release of FSH which causes sperm production. FSH production is kept in check by hormones from the testicles.

GnRH also causes release of LH which increases testosterone production. High levels of testosterone decreases GnRH production.


Brain – Pituitary – Gonad feedback loop in men

Hormones produced by the gonads (the testes in men) are released into the bloodstream and are “read” by the pituitary gland which will alter its output of FSH and LH in response.


Hormones and Sexual Desire

Testosterone plays a role in both male and female levels of sexual desire.

Testosterone levels are linked not only biological factors but also to levels of sexual activity as well as exposure to non-sexual psychological arousal.

Severely low levels of testosterone are clearly linked to low levels of sexual desire.


Anabolic Steroids

Derivatives of testosterone, these synthetic drugs promote muscle growth by enhancing protein uptake in muscle cells. Both muscle mass and strength are enhanced.

Administered in proper dosages. anabolic steroids have therapeutic value for people recovering from certain illnesses.


Misuse of Anabolic Steroids

Athletes tend to take dosages 100 times the therapeutic dose.

Physical harm includes: high blood pressure, serious cardiovascular disease, liver and prostate tumors, decrease in testicular size, breast lumps and impaired reproduction.

Psychiatric harm includes: anxiety, irritability, depression, impaired judgment and paranoia.

king, human sexuality today, 5/e (c) 2005 by prentice hall 1 chapter 3 hormones and sexuality for...

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