human

human sexuality
sexuality
Development of Secondary
Sex Characteristics.
Development of Secondary Sex
Characteristics.
• After fertilization, the
development of the
reproductive system begins.
Approximately one month
after conception primordial
gonads also begin to develop.
Rapid reproductive
development happens inside
the mother’s womb.
Puberty
• is the stage of development at which individuals become sexually mature. The
outcome of puberty is different for boys and girls, but the hormonal process is
similar. Moreover, though the timing of these changes varies for every individual,
the sequence of changes for boys and girls is predictable, resulting in adult
physical characteristics and the capacity to reproduce.

• Puberty can be separated into five stages. The characteristics for each stage vary
for girls and boys
Erogenous Zones

This Photo by Unknown author is licensed under

CC BY-NC.
What are The Erogenous Zones of The
Body?
The skin
The skin serves as the
primary erotic stimulus. Two
types Of erogenous zones exist
in the skin (Winkelmann, 2004):
1. Nonspecific Type
2. Specific Type
Nonspecific
a. It is similar to any other portion of the usual haired skin.
b. The nerves supplying it are composed of the usual density of
dermal-nerve networks and hair-follicle networks.
c. The learned and anticipated pleasurable sensations when a
stimulus is presented in these regions produce the amplified
sensation.
d. The pleasurable sensation felt from these regions is simply an
exaggerated form of tickle.
e. Examples of this type of skin are the sides and back of the neck,
the axilla (armpit, underarm) and the sides of the thorax
Specific
a. It is found in the mucocutaneous regions of the body or those
regions made both of mucous membrane and of cutaneous skin.
b. These regions favor acute perception.
c. These specific sites of acute sensation are the genital regions,
including the prepuce, penis, the female external genitalia
(vulva),the perianal skin, lips, and nipples.
The prepuce is the retractable fold of skin covering the tip of the penis.
Nontechnical name: foreskin. It is also similar fold of skin covering the
tip of the clitoris
Specific
The penis is a male erectile organ of copulation by which urine
and semen are discharged from the body.

Female External Genitalia VULVA include:

Mons Pubis
Clitoris- A female sexual organ that is small, sensitive, and
located in front of the opening of the vagina
Specific
The labia majora and labia minora. The labia majora are fleshy
lips around the vagina. These are larger outer folds of the vulva.
The labia minora also known as the inner labia, inner lips, vaginal
lips or nymphae are flaps of skin on either side of the human
vaginal opening in the vulva situated between the labia majora.

Vaginal introitus is the opening that leads to the vaginal canal.

The hymen is a membrane that surrounds or partially covers the

external vaginal
Specific
Perianal skin refers to the area of the body surrounding the anus, and
in particular, the skin. The perianal skin is very sensitive. It is also
susceptible to injury and damage.

The lips are soft, movable. and serve as the opening for food intake
and in the articulation of sound and speech. Human bps are designed
to be perceived by touch, and can be an erogenous zone when used
in kissing and any other acts of intimacy,

Nipples are the raised region of tissue on the surface of the breast. A
recent study found that the sensation from the nipples travels to the
same part of the brain as sensations from the vagina, clitoris, and
cervix (Pappas, 2011).
Male Reproductive System
Female Reproductive System
Female Reproductive System
Stages of Human Sexual
Response
Human Sexual Response

• The sexual response cycle in

humans progresses through four
phases:

• Excitement
• Plateau
• Orgasm (climax)
• Resolution
Human Sexual Response
Master’s and Johnson’s Four Phase Model

• Phases of physiological responses

• Two basic physiological processes

• Vasocongestion
• Myotonia
Excitement
Plateau
Orgasm
Resolution
Orgasm
• Shortest phase of sexual response cycle
• Men and women’s subjective descriptions of orgasm are
similar
• Most female orgasms result from stimulation of the clitoris
• Grafenberg spot
• Area on lower front wall of vagina
• Sensitive to pressure
• Sometimes results in “ejaculation”
Sex Differences in Sexual Response
• Greater variability in female response

• Male refractory period

• Women can experience multiple orgasms

Sex and The Brain
The Brain and Sexual Arousal
• Neural and hormonal involvement in
sexual responses:
• Parasympathetic:- arousal
• Sympathetic:- orgasm
• Spinal reflexes:
• erection and ejaculation
• Erection:
• sacral cord responds to stimulation, sends message
via parasympathetic to relax penile arteries: more
blood flows to penis. Also, message to brain,
awareness (not if spine severed above sacrum)
• Ejaculation:
• higher in spinal cord, message to sympathetic that
causes muscle contractions. Also, message to brain,
awareness, possibility of control
The Brain and Sexual Arousal
• Cerebral cortex (mental events)
• Reasoning, language, and
imagination
• Limbic system and sexual
behavior
• Hypothalamus
• Neurotransmitters
• Dopamine facilitates sexual
arousal
• Serotonin inhibits sexual arousal
The Brain and Sexual Arousal
• Higher Centres:
• limbic system: septal region of
the amygdala
Sex and the Brain. What parts are
involved?
Primarily, sex is the process of combining male and female genes
to form an offspring. However' complex systems of behavior have
evolved the sexual process from its primary purpose Of
reproduction to motivation and rewards circuit that root sexual
behaviors.
Ultimately, the largest sex organ controlling the biological urges,
mental processes, as well as the emotional and physical
responses to sex, is the brain.
Roles of the brain in sexual activity:

1. The brain is responsible for translating the nerve impulses

sensed by the skin into pleasurable sensations.
2. It controls the nerves and muscles used in sexual activities.
3. Sexual thoughts and fantasies are theorized to lie in the
cerebral cortex, the same area used for thinking and reasoning.
4. Emotions and feelings (which are important for sexual
behavior) are believed to originate in the limbic system.
5. The brain releases the hormones considered as the
physiological origin of sexual desire.
Roles of hormones in sexual activity:
The hypothalamus is the most important part of the brain for
sexual functioning.
This small area at the base of the brain has several groups of
nerve-cell bodies that receive input from the limbic system. One
reason the hypothalamus is important in human sexual activity is
its relation to the pituitary gland. The pituitary gland secretes the
hormones produced in the hypothalamus.
Roles of Hormones in Sexual Activity

• Oxytocin - It is also known as the "love hormone" and

believed to be involved in our desire to maintain close
relationships. It is released during sexual intercourse when
orgasm is achieved.
• Follicle-stimulating hormone (FSH)- It is responsible for
ovulation in females. The National Institute of Environmental
Health Sciences in Durham, N.C., discovered that sexual
activity was more frequent during a woman's fertile time.
Roles of Hormones in Sexual Activity

• Luteinizing hormone (LH)- The LH is crucial in regulating the

testes in men and ovaries in women. In men, the LH stimulates
the testes to produce testosterone. In males, testosterone
appears to be a major contributor to sexual motivation.
• Vasopressin- is involved in the male arousal phase. The
increase of vasopressin during erectile response is believed to
be directly associated with increased motivation to engage in
sexual behavior.
• Estrogen and progesterone- typically regulate motivation to
engage in sexual behavior for females, with estrogen increasing
motivation and progesterone decreasing it.
Understanding the
Chemistry of Lust, Love,
and Attachment
Falling in love can be a beautifully wild experience. It is a rush of longing,
passion, and euphoria. Fast forward a few years, and the excitement would
have died down (though the levels vary for every couple). For couples who
remain together through the years, the rush would have been replaced by a
warm, comfortable, and nurturing feeling.
Each stage of this cycle can actually be explained by your brain chemistry—
the neurotransmitters that get stimulated to release hormones throughout
your body.
Anthropologist Helen Fisher of Rutgers University proposed three stages of
falling in love; and for each stage, a different set of chemicals run the show.
The three stages of falling in love are:
Lust (erotic passion);
Attraction (romantic passion); and
Attachment (commitment),
Lust

• This stage is marked by

physical attraction. You want
to seduce and be seduced by
your object of affection. Lust
is driven by testosterone in
men and estrogen in women.
Lust, however, will not
guarantee that the couple will
fall in love in any lasting way.
Attraction
At this stage, you begin
to crave for your partner's
presence. You feel excitement
and energetic as you fantasize
about the things you could do
together as a couple. Three
chemicals trigger this feeling:
norepinephrine, dopamine, and
serotonin.
Attraction
Norepinephrine — responsible for the extra surge of energy and
triggers increased heart rate, loss of appetite, as well as the desire to
sleep. Your body is in a more alert state and is ready for action.
Dopamine — associated with motivation and goal-directed behavior. It
makes you pursue your object of affection. It creates a sense of
novelty, where the person seems exciting, special admirable
qualities, ' or unique that you want to tell the world about him or her.
Serotonin- is thought to cause obsessive thinking, Low levels of
serotonin are said to be in people with behavior (OCD). Meanwhile, a
study found that those who were in love and people with OCO both
had less serotonin transporter in their blood compared to those who
did not express they were in love and do not have OCD well.
Attachment
Attachment involves the
desire to have lasting
commitment with your
significant other. At this point,
you may want to get married
and/or have children.
fin