Sex differences and behaviour Flashcards
What is sex differentiation?
-The process of being either male or female
-This occurs at fertilisation when chromosomal make-up is determined
Where are the four different places sex differences can be?
1) Chromosomal
2) Gondal
3) Morphological
4) Hormonal
Describe a bit about chromosomes..
- XX = females
- XY = males
There are 46 chromosomes (23 pairs) - X chromosome is much longer than Y, little is known about Y
What is mosaicim?
(in relation to chromosomes)
This process alters symtoms severely when an abnormal chromosomal pattern occurs e.g. (XXY)
What happens in the early development and later development in Mosaicism?
Early = more cells are affected
Later = Just in specfiic organs
Tell me about gonadal.
This is a process occuring in the ovaries and testies
- it determines genetic influence
- Once the egg fertilises , the germinal ridge of the proto kidney (semi structure of teh kidney) develops into gonads
- The default development is female - whereby gonads form into ovaries
Tell me what morphological is
What the body looks like externally
Tell me about the female and male systems (Morphological)
**Female support system is called the Mullarian system **
- Includes the fallopian tubes, cervix, and uterus
Male support system is called the wolfian system
- Devlops into..
- Vas difernes which connects testies to penis
- **Seminal vesicle **- supplies things in ejaculate
What are antrogens, and what are their roles? (hormones)
Antrogens promote male development
An absense of antrogens = FEMALE DEVELOPMENT
So, testes produce antrogens
- Ovaries** do not** produce high concentration of hormones
How does male development start?
(Gonadal)
- The SRY genes is activated, which is located on the Y chromosome
- There is a sex determining region on the Y chromosome
- When activated it starts to produce the TDF protiens (testies determining factor)
- This CAUSES germinal ridge to develop the testies
What is the production of hormones like in females?
Cyclic gonadal function
(meaning, the periodic change in organs e.g. menstral cycle)
- this is in place so the body knows how mcuh hormones to produce
What is the production of hormones like in males?
Constant reproductive function
- Again, so the body knows how much and when to rpoduce hormones
Describe the release of hormones in females menstrual cycle.
- After menustration, the body prepares for the release of eggs
- Presence of LH and FSH leads to HIGHER production of estrogen and progestrone
- This causes eggs to be released from the ovaries
-
Progesterone starts to rise; it either continues to rise or return to baseline
Rise = Egg is fertilised
Baseline = no eggs, next cycle begins
Describe the release of hormones in males.
- The hypothalamus sends GnRh to the pituitary gland
- The Pituitary gland releases LH and FSH
- Travels to testies
- Testies make testosterone
Describe what is involved in the negative feedback loop, with an example.
- Testosterone is regulated by a negative feedback loop
- The **hypothalamus **and pituitary gland monitor testosterone levels
- The can increase or decrease testosterone levels
What are sexually dimorphic behaviours, and where do they come from?
- They are behaviours that are only produced by one sex
- These behavioural differences come from differences in the brain
Describe Davidson (1966) study about sexually dimorphic behaviours with a critical analysis.
Davidson (1966)
* Castration of an adult male rat of testosterone; mounting of the female rat stops
* If injected with testosterone, the mounting and behaviour resumes
Being critical..
- Female rats should mount wehn injected with testosterone. They don’t.
- Shows that there is more to behaviour than just hormones
What is the organisational/Activational hypothesis? (Phoenix et al., 1959)
Steriod hormones (e.g. testosterone) can permenantley organise the nervous system (making a change to the brain) at some point during development
- at this point the indiviudal doesnt show the behaviour but the brain has been programmed
Later in adulthood, the same steroid hormones activate, modulate, or inhibit adult male/female behaviours
- This activates the structures of the brain that have been changed through early exposure
Describe Pheonix et al (1959) study on activational hypothesis.
- Pregnant guinea pigs were given testosterone to study the affect on the offspring
-
In adulthood, the offspring was gonadectomised (got rid of gonads - either testes or ovaries) and treated with either estogrogen or testosterone to observe mating behaviour
prenatally testosterone treated females were: - less likely to display lordosis position
- more likely to display mounting behaviour with testosterone as adults
Organisational effects are permenant (regardless of hormone production, programming has been set)
Activational effects are acute -> so, mounting only happens when treated with testosterone in adulthood
What does antrogen and estrogen activate in adulthood?
In terms of the activational/organisational hypothesis
Previously programmed male/female behavioural patterns.
How does the brain become demasculinised/defeminised?
**Through Aromatisation **= the process where testosterone gets converted into estrogen in the brain
- Masculine behaviour depends on estrogen exposure: Grady et al., 1965 Injecting rat’s estrogens directly into the brain before 10 days old masculines later behaviour more so than antrogens
Why are females not masculinised?
- Estrogen is not high to develop in a female direction
- They are exposed to estrogen from the mother’s bloodstream in the womb
- Rat’s foetus’ produce alpha-fetoprotiens, protects mother from estrogenic effects
- These bind to circulating estrogens and remove it via the placenta
- Alpha - fetoprotiens do not bind to antrogens, so testosterone from male rat foetus’s is aromatised to estrogen, and has masculine effects
Describe Antrogens role as a hormone.
**Its a group of male sex hormones **- antro (ANDREW!!!)
Males show 3 peaks in antrogen production
1. 10-18 weeks gestation (differentation of reproductive system)
2. 2-6 months after birth
3. Puberty (secondary sexual characteristics)
Describe Estrogen’s role as a hormone
Involved in the development and maintainence of female sexual characteristics
There are three types
1. Estrone (E1): Hormones after menopause
2. Estradoil (E2): Steriod produced from tesosterone by gonads, and the primary hormone responsible for female characteristics and sexual functioning
3. Estroil (E3): By product of pregnancy
