Lecture 3 Flashcards
What eliminates male sex behavior and what restores it.
Castration eliminates male behavior and testosterone replaces it.
Describe differences between male and female rodents in reference to mating behaviors.
Females express lordosis and males mount to females. They both rarely do the opposite.
Does testosterone cause mounting behavior?
No. It acts as a critical period of development to program sexual behavior.
Describe Young’s hypothesis and his results.
Gonadal steroid hormones must act early in development to induce sexually dimorphic mating behavior. Results showed despite being given Steroid hormones in adulthood that typically induce sex behaviors, all adults guinea pigs exposed to testosterone early in life displayed impaired lordosis and enhanced mounting.
What are the four conclusions of the organizational/ activation hypothesis
- Prenatal steroid hormones = organization of sex differences
Postnatal/ adult steroids = activation of differentiated system - Critical periods exist for steroid hormones
- Organization is masculine/ feminine
- Organization can have subtle effects
Why are there sex differences? And how do they develop.
The causes are evolution and adaptation. They develop through mechanisms.
What are the three observations of sex differentiation.
- Sexual dimorphism differs across species.
- sexual dimorphism is related to mating system
- In polygamous species, males compete for females and females choose their mate
What are two pressures on mating
- Intrasexual selection. When males compete amongst themselves for female attention
- Intersexual selection. Where females choose males with most appealing traits.
Name the behavioral traits and morphological traits of sex differentiation.
Behavioral traits are aggression and solicitation behaviors. Morphological traits are size coloration and ornamentation.
What is sexual selection
It’s a form of natural selection where individuals differ in their ability to compete for and or attract potential mates.
Name four sexually dimorphic behaviors In human males
- increased body size/strength
- increased aggression
- distinct courtship behavior
- reduced parental care
Name in order the stages of sex determination
Chromosomal sex Gonadal sex Hormonal sex Morphological sex Behavioral sex
Briefly describe what happens in chromosomal sex and gonadal sex
In chromosomal sex an X chromosome is received from mothers ovum and and x or y is received from fathers sperm. (Xx female, xy male)
In gonadal sex the SRY region of Y chromosome encoded Testis determination factor to produce testis otherwise ovaries will be produced.
Briefly describe what happens in hormonal sex and morphological sex
In hormonal sex the human will either have more of the estrogens steroids or androgen steroids.
In morphological sex the external genitalia will either be smaller for the female or larger for the male
How does hormones influence the bipotential gonads
If there is no male hormones the mullarian duct will form which includes Fallopian tubes, uterus and cervix. If male hormones MIS, testosterone and Insi3 are present the wolffian duct will form seminal vesicles and vas deferens.
What happens when androgen concentration is low and what happens when it is high?
Masculine genital development when high feminine genital development when low.
Explain what Turner syndrome is and what happens
- Damage to x or Y chromosome
- XO genotype
- unambiguously sexed as girls at birth
- ovaries don’t produce steroid hormones
- associated with slow growth, hearing deficits and occasionally intellectual disabilities
- gene imprinting
What is the most common cause of anomalous sexual differentiation in human females.
Prenatal exposure to androgens
What is the result of the endogenous prenatal exposure to androgens.
Congenital adrenal hyperplasia is when the adrenal glands produce high concentrations of androgens instead of cortisol (moderate to severe masculinization in females)
What is Androgen Insensitivity Syndrome
It is an snp on x chomosome which results in non-functional androgen receptor
The xy males are morphologically female and usually regard themselves as female
Describe a person with 5a-reductase deficiency
- They are xy males at birth.
- ambiguous genitalia
- usually reared as female
- at puberty high levels of androgens partially masculinity the individual
What is hypospadias
Urethra opening at base of penis.
Briefly describe two trisomic anomalies
XXY Klinefelter syndrome.
y contains sry and masculinization occurs. It’s associated with sterility, learning disabilities and long limbs.
An XYY individual is sterile, above average height and below average intelligence
What does the maternal immunity hypothesis state?
That the number of older biological brother correlated with increased homosexuality in males
What is shown in the brains of homosexual men and women?
They display sex-atypical connectivity and asymmetry
Describe the positive feedback cycle of the control of ovulation
High levels of estrogen causes the surge center to release a surge of GnRH which stimulates the ant. pit. To release corresponding surges of LH and FSH which stimulates the gonads and causes ovulation.
What causes the cycle of ovulation control to go into a negative feedback.
Low levels of estrogens
What are environmental endocrine disrupters
DDT, birth control, phthalate, and Chemicals that mimic estrogens, androgens and thyroid hormones.
Some example of ED’s adverse affects on health.
Chryptochidism, hypospadias, shorter AGD,
What is a morph
Multiple types of the same sex.
Explain simultaneous and sequential hermaphroditism
Simultaneous includes ovotestes.
Sequential is either protogynous (female to male) or protandrous (male to female). And it involved change of gonadal type/ function, morphology, behavior.
