11.1 Sex And Hormones Flashcards
Male and female mammals start with the same ____ during an early stage of prenatal development.
anatomy
Females have two X ____, where as males have an X and a Y ____.
chromosomes
Both have a set of ____ ducts (precursors to femail internal structures) and a set of ____ ducts (precursors to male internal structures), as well as unidentified gonads that are on their way to becoming either testes or ovaries.
Müllerian : Wolffian
The males Y-chromosome includes the ___ (sex-determining region on the Y-chromosome) ___, which causes those primitive gonads to develop into testes, the sperm-producing organs.
SRY gene
The developing testes produce ____ (hormones that are more abundant in males) that increase the growth of the testes, causing them to produce more androgens and so forth.
androgens
Androgens also cause of the primitive Wolffian ducts, precursors for other male reproductive structures, to develop into ____ ____ (sack like structures that store semen) and the ___ ____ (a duct from the testes to the penis).
seminal vesicles : vas deferens
The testes also produce ____ ____ ____ (MIH), which causes the Müllerian ducts to degenerate.
Müllerian inhibiting hormone
Because females do not have the SRY gene, their gonads develop into ____ instead of testes, and their Wolffian ducts degenerate.
ovaries
Because a female’s ovaries do not produce MIH, females Müllerian ducts develop and mature into ____, ____, and the upper vagina.
oviducts, uterus
The males testes then produce more androgens than ____ (hormones that are more abundant in females,).
oestrogens
Androgens and oestrogens are ____ ____, containing four carbon rings, derived from cholesterol.
steroid hormones
We are often warned about the risks of excessive ____, but a moderate amount is necessary for generating these important hormones.
cholesterol
Steroids exert their effects in ____ ways. First, they bind to membrane receptors, like neurotransmitters, exerting rapid effects. Second, they enter cells and activate certain kinds of proteins in the cytoplasm. Third, they bind to receptors that bind to chromosomes, where they activate or inactivate certain genes.
three
Androgens and oestrogens are categories of ____; neither androgen nor oestrogen is a specific chemical its self.
chemicals
The most widely known androgen is ____. The most common type of oestrogen is ____.
testosterone : estradiol
_____, another predominantly female hormone, prepares the uterus for the implantation of a fertilised ovum and promotes the maintenance of pregnancy.
Progesterone
Androgens promote the development of typically ____ features, such as facial hair. Oestrogens promote typically female features, such as breast development.
masculine
For many years, biologists assumed that hormones account for all the biological differences between males and females. Later research demonstrated that some differences depend directly on control by the X and Y chromosomes ____ of hormones.
independently
At least three gene on the Y-chromosome (found only mean) are active in specific brain areas, and at least one gene on the X chromosome is active only in the ____ brain.
female
Genes on the X and Y chromosomes produce ____ differences in addition to those that we can trace to androgens and oestragens.
sex
Biologist distinguish between the organising and activating effects of ___ ____.
sex hormones
____ ____ produce long-lasting structural effects. The most prominent organising effects occur during a sensitive stage of early development determining whether the body develops female or male anatomy.
Organising effects
____ ____ are more temporary, when a hormone increases some activity that lasts only while the hormone is present. Activating effects occur at any time in life.
Activating effects
Differentiation of the ____ ____ and several aspects of brain development depend mainly on the level of testosterone.
external genitals
The human sensitive period for genital formation is about the ____ and ____ months of pregnancy.
third and fourth
Drugs that tend to ____ or demasculinise early development include alcohol, marijuana, haloperidol (and antipsychotic drug), phthalates (chemicals common in many manufactured products), and cocaine.
feminise
In short, male development is vulnerable to many sources of ____.
interference
In addition to controlling differences in the external genitals, sex hormones early in life influence development in parts of the ____, ____, and other brain areas.
hypothalamus, amygdala
One area in the anterior hypothalamus, known as the ____ ____ ____, is larger in males than in females and contributes to the control of male sexual behaviour.
sexually dimorphic nucleus
Parts of the female hypothalamus generate a cyclic pattern of hormone release, as in the human ____ ____.
menstrual cycle
Any time in life, not just during a sensitive period, current levels of testosterone or oestradiol exert activating effects, _________.
temporarily modifying behaviour
Changes in ____ ____ influence sexual behaviour within 15 minutes. Behaviours can also influence hormonal secretions.
hormonal secretions
Sex hormones facilitate sexual activity. Testosterone is essential for male sexual arousal. A combination of estradiol and progesterone is the most effective combination for females. Arousal also depends on _________.
previous experience
____ is the inability to have an erection. The most common cause is impaired blood circulation, especially in older men. Other common causes include neurological problems, reactions to drugs, and psychological tension.
Impotence
Testosterone reduction has sometimes been tried as a means of controlling ____ ____, including exhibitionists, rapists, child molesters, and those who commit incest.
sex offenders
One major practical problem is getting sex offenders to continue taking drugs that block testosterone. Another drawback is the side-effects of ____ ____, including weight gain, diabetes, and depression.
testosterone depravation
A woman’s hypothalamus and pituitary interact with the ovaries to produce the ____ ____, a periodic variation in hormones and fertility over the course of about 28 days.
menstrual cycle
After the end of the menstrual cycle, the anterior pituitary releases ____ ____ ____ (FSH), which promotes the growth of a follicle in the ovary.
follicle-stimulating hormone
The follicle in the ovary nurtures the ____ (egg cell) and produces several types of oestrogen, including estradiol.
ovum
The increased release of estradiol causes an increased release of FSH as well as a sudden surge in the release of ____ ____ (LH) from the anterior pituitary. FSH and LH combine to cause the focal to release an ovum.
luteinising hormone
The remnant of the follicle (now called the corpus luteum) releases the hormone ____, which prepares the uterus for the implantation of a fertilised ovum.
progesterone
Toward the end of the menstrual cycle, the levels of LH, FSH, estradiol, and progesterone all ____.
decline
If the ovum is not fertilised, the lining of the uterus is cast off (____), and the cycle begins again.
menstruation
The most widely used birth-control pill is the ____ ____, containing oestrogen and progesterone.
combination pill
The ________ combination thickens the mucus of the cervix, making it harder for a sperm to reach the egg, and prevents an ovum, if released, from implanting in the uterus.
oestrogen-progesterone
Changes in hormones over the menstrual cycle also alter women’s ____ ____.
sexual interest
The ____ ____, consisting of the days around the middle of the menstrual cycle, is the time of maximum fertility and high oestrogen levels. According to two studies, women not taking birth-control pills initiate more sexual activity during that period than at other times of the month.
periovulatory period
In addition to sex hormones, the pituitary hormone ____ is also important for reproductive behaviour. Oxytocin stimulates contractions of the uterus during delivery of a baby, and it stimulates the mammary gland to release milk.
oxytocin
Sexual pleasure also releases oxytocin, especially at ____. People typically experience a state of relaxation shortly after orgasm as a result of oxytocin release.
orgasm
Strong release of oxytocin facilitates formation of ____ ____ between mating partners.
pair bonds
Oxytocin also facilitate other ____ ____. When people inhaled nasal spray containing oxytocin, as compared to a placebo, they become more accurate at recognising familiar faces.
social behaviours
People sometimes call oxytocin a “love hormone”, but as you can see, that term is misleading. It might enhance your attraction towards someone you already love, but it doesn’t make you love or trust ____.
everyone
A female mammals ____ changes in many ways when she becomes a mother. In addition to nursing and caring for the young, she eats and drinks more than usual, and becomes less fearful and more aggressive, especially in defence of her young.
behaviour
____ is necessary for milk production and certain aspects of maternal behaviour, such as retrieving young when they wander away from the nest.
Prolactin
Prolactin also inhabits sensitivity to ____, enabling the mother to eat far more than usual.
leptin
In addition to secreting hormones, the female changes her pattern of hormone receptors. Late in pregnancy, her brain increases at sensitivity to estradiol in the areas responsible for ____ ____.
maternal behaviour
The hormonal changes increase the mother’s attention to their young after delivery. Hormones increase activity in the medial preoptic area and anterior hypothalamus, areas that are necessary for ____ maternal behaviour.
rats’
Another key hormone is ____, synthesised by the hypothalamus and secreted by the posterior pituitary gland. ____ is important for social behaviour in many species, partly by facilitating olfactory recognition of other individuals.
vasopressin
Hormonal changes are necessary for a woman to _______, and oxytocin levels correlate with several aspects of motherly attention to an infant.
nurse a baby
However, hormonal changes and not necessary for human parental behaviour. After all, many people ____ children and become excellent parents.
adopt
