PSYCHOLOGY the
DOC. KEVIN MOISES MW(3:30-4:30PM)
Biological Basis of Behaviors
Sex hormone
The sex hormones - estrogens, progesterone and androgens are a special category of steroid hormones
released by the gonads (testes & ovaries) and to a lesser extent by the adrenal glands
Androgens (a group that contains testosterone) is generally referred to as male hormones due to higher
levels found in males
Estrogens are female hormones because higher in females, as well as
Progesterone - prepares uterus for implantation of ovum and maintenance of pregnancy
Sex hormones affect the brain, genitals and other organs.
Organizing Effects - occur mostly at a sensitive stage of development, shortly before and after birth in rats
& during the prenatal stage in humans
They determine whether the brain and the body will develop female or male characteristics
Activating Effects - can occur at any time in life, when a hormone temporarily activates a response
Hormones early in life exert temporary effects while organizing body development, during puberty,
hormones induce long lasting structural changes, as well as activating effects.
Sexual differentiation begins with the chromosomes (XX / XY)
At the early prenatal stage, both males and females have a set of:
Wolffian ducts - precursors for male reproductive structures (seminal vesicles & vas deferens)
Mullerian ducts - precursors to the female oviducts, uterus and upper vagina
A high level of testosterone during the early prenatal stage causes genitals to develop into a male pattern
while low levels lead to the female pattern
Sex Differentiation
The human sensitive period for genital formation is about the 3rd and 4th months of pregnancy
In rats, testosterone begins masculinizing the external genitals during the last few days of pregnancy and
first few days after birth.
A genetic male will develop the female pattern of anatomy and behavior if he lacks androgen receptors, is
castrated, or exposed to substances that block testosterone effects
Substances like alcohol, marijuana, Haloperidol (antipsychotic) and cocaine feminize or de-masculinize
early sex development.
Sex differences - are biological differences between males and females
Gender Identity - is how we identify sexually
Gender differences - differences that result from people's thinking about themselves as male or female
, Sex Hormones
Sex hormones activate sexual behaviors partly by enhancing sensations
Estrogens increase sensitivity of the pudendal nerve, which transmits tactile sensations from the pubic area
to the brain
Sex hormones bind to receptors that increase activity in specific areas of the hypothalamus: ventromedial
nucleus, medial preoptic area (MPOA) & anterior hypothalamic area also known as sexually dimorphic
nucleus (SDN)
Stimulating the SDN causes increased sexual behaviors in male species
Testosterone & estradiol prime the MPOA and several areas to release dopamine
MPOA neurons release dopamine strongly during sexual activity, and the more dopamine released, the
more likely the male is to copulate.
Although humans are less dependent on sex hormone levels than other species, hormones alter people's
sexual arousal
Testosterone also decreases pain and anxiety, and decrease of sex hormones in men being treated for
prostate cancer lead to impairments of memory (Bussiere et.al, 2005)
Estrogen stimulates the growth of dendritic spines in the hippocampus
Effects
On men… On women…
- Among males, level of testosterone correlate A woman's hypothalamus and pituitary interact with
positively with sexual arousal and the drive to seek the ovaries to produce the menstrual cycle - a
sexual partners periodic variation in hormones and fertility over the
course of about 28 days.
- Married men tend to have lower testosterone levels
than single unpaired men of the same age (McIntyre The anterior pituitary releases follicle stimulating
et al, 2006) hormone (FSH) at the end of the menstrual period to
promote growth of follicle in the ovary.
- Men with lower testosterone levels are more likely to
marry than men with higher testosterone levels (van Towards the middle of the menstrual cycle, more
Anders & Watson, 2006) receptors to FSH is built up and increase amounts of
estradiol and release of luteneizing hormone LH cause
- Men with high testosterone who marry tend to the follicle to release an ovum
engage in extramarital affairs
Birth control pills prevent pregnancy by interfering with the usual feedback cycle between the ovaries &
pituitary.
The combination pill prevents the surge of FSH and LH that would otherwise release an ovum.
It also thickens the mucus of the cervix, making it harder for the sperm to reach the egg & prevents an
ovum from being implanted in the uterus
Changes in hormones over the menstrual cycle alter women's sexual interest
The periovulatory period, at the middle of the cycle is the time of maximum fertility and high estrogen
levels
Women not taking pills initiate more sexual activity during the periovulatory period than an other times of
the month
DOC. KEVIN MOISES MW(3:30-4:30PM)
Biological Basis of Behaviors
Sex hormone
The sex hormones - estrogens, progesterone and androgens are a special category of steroid hormones
released by the gonads (testes & ovaries) and to a lesser extent by the adrenal glands
Androgens (a group that contains testosterone) is generally referred to as male hormones due to higher
levels found in males
Estrogens are female hormones because higher in females, as well as
Progesterone - prepares uterus for implantation of ovum and maintenance of pregnancy
Sex hormones affect the brain, genitals and other organs.
Organizing Effects - occur mostly at a sensitive stage of development, shortly before and after birth in rats
& during the prenatal stage in humans
They determine whether the brain and the body will develop female or male characteristics
Activating Effects - can occur at any time in life, when a hormone temporarily activates a response
Hormones early in life exert temporary effects while organizing body development, during puberty,
hormones induce long lasting structural changes, as well as activating effects.
Sexual differentiation begins with the chromosomes (XX / XY)
At the early prenatal stage, both males and females have a set of:
Wolffian ducts - precursors for male reproductive structures (seminal vesicles & vas deferens)
Mullerian ducts - precursors to the female oviducts, uterus and upper vagina
A high level of testosterone during the early prenatal stage causes genitals to develop into a male pattern
while low levels lead to the female pattern
Sex Differentiation
The human sensitive period for genital formation is about the 3rd and 4th months of pregnancy
In rats, testosterone begins masculinizing the external genitals during the last few days of pregnancy and
first few days after birth.
A genetic male will develop the female pattern of anatomy and behavior if he lacks androgen receptors, is
castrated, or exposed to substances that block testosterone effects
Substances like alcohol, marijuana, Haloperidol (antipsychotic) and cocaine feminize or de-masculinize
early sex development.
Sex differences - are biological differences between males and females
Gender Identity - is how we identify sexually
Gender differences - differences that result from people's thinking about themselves as male or female
, Sex Hormones
Sex hormones activate sexual behaviors partly by enhancing sensations
Estrogens increase sensitivity of the pudendal nerve, which transmits tactile sensations from the pubic area
to the brain
Sex hormones bind to receptors that increase activity in specific areas of the hypothalamus: ventromedial
nucleus, medial preoptic area (MPOA) & anterior hypothalamic area also known as sexually dimorphic
nucleus (SDN)
Stimulating the SDN causes increased sexual behaviors in male species
Testosterone & estradiol prime the MPOA and several areas to release dopamine
MPOA neurons release dopamine strongly during sexual activity, and the more dopamine released, the
more likely the male is to copulate.
Although humans are less dependent on sex hormone levels than other species, hormones alter people's
sexual arousal
Testosterone also decreases pain and anxiety, and decrease of sex hormones in men being treated for
prostate cancer lead to impairments of memory (Bussiere et.al, 2005)
Estrogen stimulates the growth of dendritic spines in the hippocampus
Effects
On men… On women…
- Among males, level of testosterone correlate A woman's hypothalamus and pituitary interact with
positively with sexual arousal and the drive to seek the ovaries to produce the menstrual cycle - a
sexual partners periodic variation in hormones and fertility over the
course of about 28 days.
- Married men tend to have lower testosterone levels
than single unpaired men of the same age (McIntyre The anterior pituitary releases follicle stimulating
et al, 2006) hormone (FSH) at the end of the menstrual period to
promote growth of follicle in the ovary.
- Men with lower testosterone levels are more likely to
marry than men with higher testosterone levels (van Towards the middle of the menstrual cycle, more
Anders & Watson, 2006) receptors to FSH is built up and increase amounts of
estradiol and release of luteneizing hormone LH cause
- Men with high testosterone who marry tend to the follicle to release an ovum
engage in extramarital affairs
Birth control pills prevent pregnancy by interfering with the usual feedback cycle between the ovaries &
pituitary.
The combination pill prevents the surge of FSH and LH that would otherwise release an ovum.
It also thickens the mucus of the cervix, making it harder for the sperm to reach the egg & prevents an
ovum from being implanted in the uterus
Changes in hormones over the menstrual cycle alter women's sexual interest
The periovulatory period, at the middle of the cycle is the time of maximum fertility and high estrogen
levels
Women not taking pills initiate more sexual activity during the periovulatory period than an other times of
the month
