Chapter 10: HORMONAL CONTROL OF SEXUAL BEHAVIOR Flashcards
What do hormones regulate?
physiological processes
What are sex hormones called?
steroids
What releases sex hormones?
Endocrine gland
By what are endocrine glands regulated?
Pituitary gland
What affect the function of a hormone?
Hormone structure
What is the male hormone?
Testosterone T
What is the female hormone?
Estradiol E2
What is estrogen E2 composed of?
T (androgen) and aromatase
what are the main sex hormones?
-Androgens, estrogens, luteinizing hormone (LH), and follicle-stimulating hormone (FSH)
Can oxytocin and vasopressin be considered sex hormones?
- YES
- either lead to or result from sexual activity
Where are sex steroids made and secreted?
-By the gonads (testes and ovaries)
Where are sex steroids synthesized ?
-adrenal glands and adipose tissue
slide 40
Classification fo sex steroid hormones
How does the brain connect with the reproductive system?
With the HPG axis
How do the pituitary and the hypothalamus communicate with each other and the gonads?
via hormones
how is testosterone secreted in males?
LH binds to cells inside the testes and causes them t secrete testosterone.
What does FSH do by stimulating other cells?
-stimulate other cells which release androgen-binding proteins and promotes testosterone binding
What does the interaction of the HPG axis do in women?
regulates menstruation and the reproductive cycle
What does the FSH and LH feedback loop do? in women
-activates the ovarian cycle
How is the menstrual cycle regulated and affected?
- Regulated by GnRH and
- affected directly by changes in levels of estrogen and progesterone.
Are humans the only species who have menstrual cycles?
- Nearly only
- other mammals have estrous cycles.
What are the primary features that distinguish menstrual cycles from estrous cycles?
- monthly growth and loss of the lining of the uterus
- estrous cycle of other mammals can be shorter
- sexual behavior of female mammals with estrous cycles is linked to ovulation whereas most female primates can mate at any time during their menstrual cycle
What are the four phases of a menstrual cycle?
- follicular phase: proliferative phase or preovulatory phase
- ovulation
- luteal phase: secretory phase or postovulatory phase
- menstruation
What happens during the follicular phase?
- secretion of gonadotropins (FSH), by the anterior pituitary gland
- stimulates growth of follicles in the ovaries
- one follicle begins to ripen and brings an egg to fertility
- follicle secretes estrogen (estradiol)
What happens during ovulation? and what is it caused by
- caused by LH surge
- follicle ruptures open and releases the ripened egg
What happens during the luteal phase
- Ruptured follicle turns into the corpus luteum
- corpus luteum produces progesterone
- progesterone promotes pregnancy
What happens during menstruation?
- ovum has not met any sperm cell
- shedding of the inner lining of the uterus
Back to the follicular phase after menstruation, what happens?
-endometrium proliferates
Back to luteal phase after menstruation, what happens?
-progesterone secreted by the corpus luteum stimulates the glands of the endometrium to start secreting the nourishing substances.
Back to luteal phase after menstruation, what happens?
-progesterone secreted by the corpus luteum stimulates the glands of the endometrium to start secreting the nourishing substances.
How long does an average normal menstrual cycle last?
28 days
From what day to what day does menstruation last?
-Day 1 to day 4 or 5
From what day to what day does the follicular phase last?
-Day 5 to day 13
From what day to what day does ovulation last?
occur on day 14
From what day to what day does the luteal phase last?
From day 15 to the end of the cycle
what hormone does sexual behavior depend on in male animals?
- testosterone
- oxytocin also plays a role
What is the refractory period ?
Period of time after a particular action (for example, an ejaculation by a male during which action cannot occur again.
What role does oxytocin play in male sexual behaviour?
- released during orgasm
- appears to contribute to the contractions of the smooth muscle in the male ejaculator system
- same for female+ role in lactation
What hormones does sexual behavior in female mammals depend on?
-estradiol and progesterone
When do levels of estradiol and progesterone increase in female mammals?
- increase just before onset of the receptive period
- levels decrease after ovulation
What is lordosis response ?
- Happens during the estrus (beginning of the estrous cycle)
- A spinal reflex seen in many four-legged female mammals. Arching of the back in response to approach of a male or to touching the flanks, which elevates the hindquarters.
What is receptivity?
Females’ ability and willingness to copulate by displaying lordosis when a male attempts to mount her.
What is proceptivity?
Females’ interest in copulation, as shown by seeking out a male and engaging in behaviors that tend to increase his sexual interest
What is attractiveness?
Physiological and behavioral changes in the female that affect the male.
Slide 53
Organizational effects of testosterone.
How is a woman’s sexual interest, behaviour and physiology influenced?
- ovarian hormones
- androgens
What effect does T have on the sexual behaviour of men?
-activational effect
How can T levels be affected in men?
- sexual activity
- thinking about it
What happens when a rodent’s brain is not exposed to androgens during a critical period of development?
the animal will engage in female sexual behavior as an adult
What happens when a rodent brain is exposed to androgens during development ?
- behavioral defeminization
- behavioural masculinization
What is behavioral defeminization?
organizational effects of androgens that prevents the animal from displaying female sexual behaviour in adulthood
What is a pheromone?
A chemical released by one animal that affects the behavior or physiology of another animal; usually smelled or tasted.
What sensory organ are the effects of pheromones mediated by?
the vomeronasal organ
where does the VNO project to?
accessory olfactory bulb
What are pheromones produced by?
apocrine glands in the armpit and the pubic areas.
What is the McClintock effect?
Menstrual pheromones cause women to develop menstrual synchrony
What is androstadienone?
- a steroid hormones found in men’s sweat
- seems to increase blood flow to regions of women’s brains that are tied to sexual behaviour in animals.
What is the Lee-Boot effect?
Estrous cycles stop in groups of female rodents living together.
What is the Whitten Effect?
Groups of female rodents who are not cycling are exposed to male urine and begin cycling synchronously
What is the Vandenbergh effect?
Acceleration of onset of puberty in female rodents exposed to odor of male
What is the Bruce effect?
Exposure to urine of novel male results in failure of pregnancy in newly pregnant female.
