The role of chromosomes & hormones Flashcards
When is the sex of the baby determined?
conception when the sperm and ovum form a zygote (fertilised egg)
What does the 23rd chromosome contain?
DNA instructions to determine the zygote’s sex
What chromosome does the ovum supply?
X chromosome (female)
What chromosome does the sperm contribute?
X or a Y chromosome (male)
What genitalia do male and female embryos up to 8 weeks have?
Similar external genitalia
What happens at 8 weeks to a male embryo?
genetically XY males produce androgens which stimulates the development of male genitalia
What is Androgen Insensitivity Syndrome (AIS) ?
a rare condition where an XY male foetus is insensitive to androgen, thus male genitals do not appear meaning that the newly born infant although genetically male will have female genitals and be labelled as female.
What are hormones?
Chemical substances secreted by glands throughout the body and carried in the bloodstream
What is testosterone?
a sex hormone, which is more present in males than females, and affects development and behavior both before and after birth.
What happens when testosterone is released in the womb?
development of male sex organs (at 8 weeks) and acts upon the hypothalamus which results in the masculinisation of the brain
What does testosterone typically cause?
male behaviors such as: Aggression, competiveness, Visio-spatial abilities, higher sexual drive
What does Oestrogen do?
females governs the development of secondary sexual characteristics and menstruation from adolescence onwards.
What does Oxytocin do?
promotes feelings of bonding, contentedness and calming. It is particularly important in breastfeeding to promote lactation and is released at times of stress to reduce the fight-flight response.
What happened when the non-human animals where give the opposite gender hormones?
Rats:
- Young, rats showed reserved sex behaviours
- Boy rats lordosis position and females attempting to mount them
Suggesting hormones play an essential role in sex bahaviours
What are other influences behind gender behaviour?
Social, cultural and parental influences during socialisation also have a part to play.
For example, congenital adrenal hyperplasia (CAH) occurs when XX females are exposed to unnaturally high levels of testosterone in the womb which results in rudimentary male genitalia at birth.
