KIN 140 Section 11 Dr Mike Walsh
One’s sexuality is a product of their biology and the social conditioning they have
received. Biology is used to determine if someone is male or female. Man and woman
refer to the psychosocial roots of our sexuality.And masculinity and femininity refers to
the resultant of one’s biology and psychosocial experience.
A. Biological Basis of Sexuality
1. Genetic Basis
The biological basis of our sexuality is determined by whether an X sperm cell or a Y
sperm cell wins the race to the egg. The egg is haploid (one set of chromosomes) X if it
is fertilized by a haploid X sperm cell, a biological female (diploid) is produced. If the
haploid X egg is fertilized by a haploid Y sperm cell then a biological male is produced.
2. Gonadal Basis
Development of gonads: testes for males and ovaries for females, occurs within the first
trimester of pregnancy.
Development of male reproductive organs will take place if there is a presence of the
SRY gene (sex-determining region on the Y chromosome) is expressed to make the
protein testis-determining factor (TDF). If the SRY gene is not present, then female
gonads will develop.
3. Structural Basis
In general, there is slow growth through childhood. In puberty there is an increase in
male and female hormone (testosterone and estrogen (both are also needed for gonadal
basis) that stimulates the growth of secondary sexual characteristics. In females,
menarche also occurs at this time and both genders become capable of sexual
In males, normally testosterone is converted to a more potent form, dihydrotestosterone,
by the enzyme 5-alpha reductase.
Males lacking this enzyme often have female appearance and genitals and behaviour until
puberty then develop male sex organs and behavior. 2
In the Dominican Republic, the incidence of 5-alpha reductase deficiency can be 1-2 %.
These male children are called 'guevedoces' (literally, penis at 12 years). In later life, they
to do not have male pattern baldness
Females are born with a full complement of eggs.At menopause they have an abrupt
cessation of reproductive capacity. This usually occurs at the age of about 50. Males have
a gradual reduction in spermatogenesis but can be still be reproductive past 70.
While there is some debate about exact egg number, it is remarkable that one cell can last
B. Psychosocial Basis of Sexuality
1. Gender Identity
By the age of about 18 months, the infant recognizes itself as male or female and is quite
robust by 3 yr. It is your own personal feelings combined with what you think you have
in common with others.
2. Gender Preference
The infant and child are steered subtly and /or overtly toward behaviours considered
appropriate for the gender. This is done primarily by the parents but also by many outside
influences. Whether this gender preference stage is truly environmental or has some
genetic basis is open for discussion. Either way, if you ask some 7 year old children if
they would be happier changing gender, you will get some very definitive responses.
Certainly most children are very comfortable with their bodies, except for perhaps
3. Gender Adoption
Observing, watching, and practicing what adults do enables the child and adolescent to
begin thinking, feeling, and acting like an adult of their gender. Obviously, television can
play a large part in gender adoption.
Also learning the psychological attributes of the opposite gender is important to the
development of a balanced sexuality. 3
4. Adult Gender Identification
The final development of an adult image of oneself is in a gender-specific context. Of
course this image may differ substantially between people because of their differing
genetics and experience. This final image may also be changing with time: male levels of
testosterone and viable sperm are decreasing.
5. Androgyny (andro=male, gyny=female)
Androgyny is having a self-image that incorporates aspects of both genders. This
combination of masculine and feminine qualities is more prevalent today than in past
decades and centuries.
In general, people who demonstrate a less polarized sexual image and a more
androgynous one have greater self-esteem, more social, psychologically more flexible,
and have more motivation to achieve.
C. Sex Anatomy and Physiology
1. Female Sex Organs
The female anatomy in their genital region, from anterior to posterior, is the clitoris,
urinary opening, vaginal opening, and anus.
The clitoris is very sensitive to touch, hence it plays an important part of sexual arousal
The vaginal opening leads to the internal reproductive organs. It is the orifice of choice
for most heterosexual intercourse, and it is also the birth canal.
The vaginal opening is initially partially covered by the hymen. The hymen is ruptured
during a woman’s first intercourse. It can also be ruptured by athletic activity. This means
the absence of a hymen is not necessarily an indication of lost virginity.
2. Male Sex Organs
Male organs in the genital area going anterior to posterior are the penis, testicles, and
At the head of the penis is the opening for the urethra, which serves for both the voiding
of urine and ejaculation of semen. 4
The testicles are, by design, located exterior to the body core to maintain sperm
temperature about 2.5 C lower than core temperature. Small changes in temperature
strongly affect the viability of the sperm. The scrotum can substantially decrease its size
when temperature is lower.
This is when a male cuts off another male’s (not anesthetized) foreskin when all the other
males leave the room. The reasons for this are cultural and religious. There is very little
medical evidence to support the prevalence of this procedure.
However, lately it has been shown that circumcised males suffer less STDs. This can be
important in Africa since circumcision may reduce the spread ofAIDS.
4. Female Sexual Cycle (aka Menstrual Cycle)
The menstrual cycle is a monthly ovarian (thus female) cycle in which an egg is made
receptive to fertilization and if fertilization does not occur there is a loss of blood and the
enriched tissue lining of the uterus. The average female cycle is about 28 days although
the duration between women does vary from 20-45 days.
The average female’s first menstrual cycle (aka menarche) occurs at 12.8 yr with a
substantially large but normal range.
The menstrual cycle consists of 4 phases: menses, estrogenic phase, ovulation, and
The onset of menstrual bleeding indicates day 1. With low levels of estrogen and
progesterone, the outer portions of the endometrial lining degenerate and separate from
the endometrium. The loss of blood and epithelial lining normally lasts about 5 days.
b. Estrogenic Phase (aka Follicular Phase: ~8 days)
Begins when menstrual flow ceases. Luteinizing hormone (LH) and follicle stimulating
hormone (FSH) are released in greater amounts from the anterior pituitary gland. Follicle
stimulating hormone stimulates the egg/follicle to make estrogen.
The uterine lining (endometrium) begins to thicken and gets enriched with blood vessels
and glands in response to the increasing estrogen produced by the follicle. Thus the
endometrium is prepared for implantation by a fertilized egg. 5
During this phase 5-25 follicles are released. Of these, a single follicle increases in size
from 25 um to 15 mm diameter in response to the combined effects of LH, FSH, and
estrogen. Of course the egg inside the follicle is much smaller.
c. Ovulation (1 day)
Rapid increase in estrogen stimulates an increase in LH which induces ovulation: the
release of the ovum from the follicle. This occurs at about day 14. The remaining follicle
becomes the corpus luteum.
d. Progestational Phase (aka Luteal Phase: 7-13 days)
The remaining follicle tissue becomes luteinized (made yellowish) into the corpus luteum
The corpus luteum is a separate endocrine organ that generates progesterone secretion
and estrogen secretion. These hormones (especially progesterone at this time) stimulate
the continued growth and development of the endometrial lining. They also inhibit
further secretion of LH and FSH from the pituitary gland.
If the egg does not become fertilized in the next about 12 days, the corpus luteum is
preprogrammed to degenerate.
Estrogen and progesterone decrease and can no longer maintain the uterine lining which
then becomes the start of menses.
Women are more creative in this phase.
D. Responsible Sexual Behaviour
It is difficult to express your intentions and determine your partner’s when the hormones
are flowing. To practice responsible sexual behaviour, it is necessary to understand why
the sexual activity is occurring.
Sex can be to express love, make babies, or attain physical gratification. Most sexual acts
involve the latter.
Most high school-aged males that engage in sexual activ