Sex differences and behaviour

Question 1

What is sex differentiation?

Answer 1

-The process of being either male or female
-This occurs at fertilisation when chromosomal make-up is determined

Question 2

Where are the four different places sex differences can be?

Answer 2

1) Chromosomal
2) Gondal
3) Morphological
4) Hormonal

Question 3

Describe a bit about chromosomes..

Answer 3

• XX = females
• XY = males
  There are 46 chromosomes (23 pairs)
• X chromosome is much longer than Y, little is known about Y

Question 4

What is mosaicim?
(in relation to chromosomes)

Answer 4

This process alters symtoms severely when an abnormal chromosomal pattern occurs e.g. (XXY)

Question 5

What happens in the early development and later development in Mosaicism?

Answer 5

Early = more cells are affected
Later = Just in specfiic organs

Question 6

Tell me about gonadal.

Answer 6

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

Question 7

Tell me what morphological is

Answer 7

What the body looks like externally

Question 8

Tell me about the female and male systems (Morphological)

Answer 8

**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

Question 9

What are antrogens, and what are their roles? (hormones)

Answer 9

Antrogens promote male development
An absense of antrogens = FEMALE DEVELOPMENT
So, testes produce antrogens
- Ovaries** do not** produce high concentration of hormones

Question 10

How does male development start?
(Gonadal)

Answer 10

1. The SRY genes is activated, which is located on the Y chromosome
2. There is a sex determining region on the Y chromosome
3. When activated it starts to produce the TDF protiens (testies determining factor)
4. This CAUSES germinal ridge to develop the testies

Question 11

What is the production of hormones like in females?

Answer 11

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

Question 12

What is the production of hormones like in males?

Answer 12

Constant reproductive function
- Again, so the body knows how much and when to rpoduce hormones

Question 13

Describe the release of hormones in females menstrual cycle.

Answer 13

1. After menustration, the body prepares for the release of eggs
2. Presence of LH and FSH leads to HIGHER production of estrogen and progestrone
3. This causes eggs to be released from the ovaries
4. Progesterone starts to rise; it either continues to rise or return to baseline
   Rise = Egg is fertilised
   Baseline = no eggs, next cycle begins

Question 14

Describe the release of hormones in males.

Answer 14

1. The hypothalamus sends GnRh to the pituitary gland
2. The Pituitary gland releases LH and FSH
3. Travels to testies
4. Testies make testosterone

Question 15

Describe what is involved in the negative feedback loop, with an example.

Answer 15

• Testosterone is regulated by a negative feedback loop
• The **hypothalamus **and pituitary gland monitor testosterone levels
• The can increase or decrease testosterone levels

Question 16

What are sexually dimorphic behaviours, and where do they come from?

Answer 16

• They are behaviours that are only produced by one sex
• These behavioural differences come from differences in the brain

Question 17

Describe Davidson (1966) study about sexually dimorphic behaviours with a critical analysis.

Answer 17

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

Question 18

What is the organisational/Activational hypothesis? (Phoenix et al., 1959)

Answer 18

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

Question 19

Describe Pheonix et al (1959) study on activational hypothesis.

Answer 19

• 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

Question 20

What does antrogen and estrogen activate in adulthood?

In terms of the activational/organisational hypothesis

Answer 20

Previously programmed male/female behavioural patterns.

Question 21

How does the brain become demasculinised/defeminised?

Answer 21

**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

Question 22

Why are females not masculinised?

Answer 22

• 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

Question 23

Describe Antrogens role as a hormone.

Answer 23

**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)

Question 24

Describe Estrogen’s role as a hormone

Answer 24

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

Question 25

Describe progesterones role as a hormone

Answer 25

It is linked to the menstrual cycle, pregnancy, adn development
- Comes from the ovaries and corpus leptum

Question 26

What is the corpus leptum?

Answer 26

A temporary gland where egg used to be
- produces a lot of temporary hormones until egg inplants and embryo starts making hormones itself

Question 27

Describe role of estrogen and progesterone in men

Answer 27

• Estrogen is produced from testosterone
• Progesterone is converted into estradoil
• Derived from cholesterol
  AND… developed into testies

Question 28

Tell me about testosterone synthesis in males

Answer 28

• Leydig cell in the testes produce 95% of testosterone in the male body from cholesterol
• Enzymes take/add pieces and through transformation, we have testosterone
• the remaining 5% is produced by adrenal glands

Question 29

Tell me about testosterone synthesis in females

Answer 29

• The aromatase enzyme converts testosterone into estradoil
• Produced by ovaries (50%), adrenal glands (50%)
• 1/10th of male levels