Sex Differences and Sex Differences in Behaviour Flashcards
What are the 4 types of sex differentiation?
1) Hormonal
2) Morphalogical
3) Chromosomal
4) Gonadal
Where does sex difference occour?
At fertilization where chromosomal makeup is determined.
What are the two types of Chromosome pairs?
XX = Female
XY = Male
Define Mosaicism
When there is an abnormality with Chromosomal makeup, mosaicism alters the severity of symptoms.
What symptoms arise with an XXX (triple X) chromosomal makeup?
Appears as female, but its cognitively impaired, and appears taller than average.
How and when do the gonads develop?
- At 6-7 weeks old.
- The geminal ridge of the protokidney develops into the Gonads.
- Default is always in a female direction, to the ovaries.
Describe the process how male development is initiated.
- The SRY gene located on the Y chromosome activates.
- This gene produce TDF proteins (Testies Determining Factor)
- This causes the germinal ridge to develop on the testies.
What does morphological sex differences mean?
What the body appears like externally
What are the two morphological systems?
Wolfian System (Men) and Mullarian System (Women)
What consists of the Mullarian System?
Fallopian tubes, ovaries, cervix.
What consists of the Wolfian System?
Vas Difernes (connects testies to penis) and Seminal Vesicle (supplies in ejaculate).
How do hormones influence sex differentiation?
Androgens influence the development in a male direction.
Absense of androgens lead to female development.
List 5 affects that Testosterone characterise in Men?
- Muscle growth
- Bone formation
- Mood
- Memory function
- Sex drive
- Metabolism
What is an Androgen?
A group of hormones associated to men.
What is the name of cells which produce testosterone?
Leydig Cells.
Where does Testosterone derive from, and why?
Testosterone is derived from Cholesterol.
Because it is a steriod hormone
Cholesterol is the precurser for all vertebrae steriod hormones.
What are the three types of Estrogens?
1) Estrone (Hormones after menopause)
2) Estradoil (Steriod hormone produce from testosterone from the gonads)
3) Estroil (A by-product of pregnancy)
Define Estrogen Hormones.
Development and maintainance of female sexual characteristics.
Decribe Testosterone Synthesis in Women.
- Testosterone is** converted to estradoil by aromatize enzymes.**
- Produced by the ovaries and gonads
Describe the Testosterone Synthesis in Men
- Leydig Cells in the Testies produce 95% of testosterone in men.
- The remaining 5% is produced by Cortisol.
What is Progesterone?
A hormone which influences the mentraul cycle, pregnancy, and development.
How is Progesterone produced?
Through the Corpus Letum
What is the Corpus Letum?
- Where Progesterone is produced.
- A temporary gland where the egg used to be which produces hormones until an egg implants and makes hormones itself.
How does Estrogen occour in men?
Produced from Testosterone in the Testies.
How does progesterone occour in men.
-Progesterone precurses from Cholesterol.
- Progesterone is converted to estradoil
How do women control the amount of hormones in the body?
Cyclic gonadal functioning
How do men control the amount of hormones in the body?
Constant reproductive function
How are hormones controlled for in the body?
Through positive and negative feedback loops
How is estrogen and progesterone controlled for in the menstrual cycle?
- The Hypothalmus released GnRH, which signals the release of Gondatropins (LH and FSH) from the pituitary gland.
- LH and FSH lead to higher concentrations of estrogen and progesterone.
- This leads to the release of eggs.
- Progesterone rises at this time. It either continues to rise, or returns to baseline.
- This depends if an egg is fertilised.
Describe the negative feedback loop in the menstraul cycle.
- High levels of estrogen and progesterone inhibit GnRH secretion, while low levels stimulate its release. - This negative feedback mechanism helps regulate the timing and duration of the menstrual cycle.
Describe the positive feedback loop in the menstraul cycle.
- As estrogen levels rise during the follicular phase, they eventually reach a threshold that triggers a positive feedback loop on the anterior pituitary, causing a surge in LH secretion.
- This LH surge triggers ovulation, the release of a mature egg from the ovary.
Describe the negative feedback loop in the male reproductive process.
- Hypothalamus sends GnRH to pituitary, which releases LH and FSH.
- This stimulates the testies the make testosterone.
- Negative feedback loop = Hypothalmus and pituitary gland monitor testosterone release, in coordination with testosterone levels
What are gonadotropins?
LH and FSH
Where are gonadotropins released from?
The pituitary gland
What does a sexually dimorphic behaviour mean?
Behaviours which are distinct between two sexes.
Name the study which explains sexually dimorphic behaviours.
Davidson (1966)
Describe Davidson (1966) study.
- Studied rats
- Castrated the rat of testosterone.
- Subsequently, the male rat did not assume the mounting position during sex.
- If testosterone was reinstated, mounting was ressumed.
Give 1 critique to Davidson (1966) findings.
- When female rats were injected with Testosterone, they did not assume the mounting position.
- There is more to behaviour than simply hormonal control.
Explain the activational/ organisational hypothesis.
Steriod hormones can permanently organize the nervous system at some point during development. Later in adulthood, the same steriod hormone activates, modulates, or inhibits adult-typical male/female behaviours (changed from early exposure)
Name the gold-standard study which explains the activational, organisational hypothesis.
Phonix et al. (1959)
Describe the procedure and findings of Phonix et al. (1959) study.
- Researchers injected pregnant guinea pig of testosterone to study the effects on the offspring.
- In adulthood, offspring were gonadectomized (couldn’t produce hormones of their own) and injected with either testosterone or estrogen to observe mating behaviour.
- Prenatal testosterone-injected females were less likely to assume the lordis position, and instead display mounting behaviour when treated with Testosterone.
Why does estrogen have masculisation effects on male rats?
- Testosterone is converted to estrogens through aromatisation.
- Alpha-fetoprotein do not bind to androgen, so testosterone is aromatized to estrogen, having a masculine effect.
Why are females not masculinised?
- Estrogen is not high during female sex development.
- AFP bind to estrogen in the mothers bloodstream in the womb.
- The absence of high levels of testosterone allows for the development of female reproductive organs and the feminization of the brain, leading to typical female behavioral characteristics.
What are alpha-fetoproteins?
Protects the feotus from estrogenic effects
Name two other sources of behavioural sex differences.
1) Intra-uterine environment
2) Maternal Physiology
What did Meisal and Ward (1981) find about the intra-uterine environment?
- A rat’s ovaries are at the top, and the uterus is at the bottom.
- Embryo’s line up ontop of each other when inside the mother.
- Bloodflow passes through each embryo, leaving by-products and hormones behind.
- If a female embryo is situated inbetween two male embryo’s, there is high exposure to Testosterone.
- Female embryo is more likely to show male typical behaviours.
What did Ward and Reed (1985) find about maternal physiology?
- A mothers hormones can interfer with hormone production of their foetus.
- Studied male rats, and stress levels in a mother.
- Cortisol affected the androgen production of the foetus, reducing male-typical behaviour in adulthood.
