Transcript 3a Biological - hormones and genes 2012

Unit 3 – GENDER DEVELOPMENT
Role of Hormones & Genes
Bio-Social
Approach
Biological influences on
gender
Evolutionary explanation
e.g. Darwin
The effect of hormones and genes on gender
development (identity + behaviour)
• Herm clip- CAH clip
Biological
Psychological
or just for pleasure.. ??
Role of hormones and genes
Possible Questions..
• Outline the role of hormones and genes in
gender development (9 marks)
Or…
• Outline the role of hormones and genes in
intersex conditions of gender development
(9 marks)
Biology!
• The specification requires you to know about
the role of genes and hormones and
sometimes
• You could be asked an exam question on
biological influences
Describing the various ways in which we distinguish between
male and female:
sex
Male
gender
Male
Acceptable
behaviour
masculine
Gender identity
male
XY
Gender roles
Breedwinner
manly
Female
XX
Female
feminine
female
housewife
caring
Drawing time …
A2 Psychology Summary of role of genes / hormones in gender development
Genes instruct hormones to determine sex of individual e.g. SRY gene on the
Y chromosome controls whether gonads become ovaries or testes.. By
releasing testosterone/progesterone at week 8 of gestation
1. Week 8 of gestation
2. Pituitary gland
Testosterone instruct gonads
form Wolffian
ducts - testis +
penis
Progesterone –
instruct gonads
become
Mullerian ducts –
Fallopian tubes +
ovaries + vagina
Gonads
Testis
Ovaries
The roles of hormones and
genes....
It is also worth noting that it is difficult
to separate the role of genes from
the role of hormones in trying to
explain any type of behaviour.
There are 5 categories of biological sex..
1. Chromosomal sex:
• Simply put, chromosomes are the structures
that hold our genes.
• Genes are the individual instructions that tell
our bodies how to develop and keep our
bodies running healthy.
• In every cell of our body there are 20,000 to
25,000 genes that are located on 46
chromosomes.
• These 46 chromosomes occur as 23 pairs.
• We get one of each pair from our mother in
the egg, and one of each pair from our father
in the sperm.
• The first 22 pairs are labelled longest to
shortest. The last pair are called the sex
chromosomes labelled X or Y.
• Females have two X chromosomes (XX), and
males have an X and a Y chromosome (XY).
• Therefore everyone should have 46
chromosomes in every cell of their body.
• If a chromosome or piece of a chromosome is
missing or duplicated, there are missing or
extra genes respectively.
• When a person has missing or extra
information (genes) problems can develop for
that individual's health, development and
gender !
These descriptions say there are 46 chromosomes and
that it is a male or female.
46,XX - Normal Female
Karyotype
46,XY - Normal Male
Karyotype
2. Gonadal sex: males have testes and
females ovaries.
• The SRY gene on the Y chromosome controls
whether gonads become ovaries or testes,
only if the gene is present will testes appear.
• In addition to the fact that XY chromosomes
start to produce hormones from week eight of
gestation and there is another surge of
production after birth for the first six months.
• The testes are two egg-shaped male
reproductive organs located in the scrotum.
They produce sperm and the male hormone,
testosterone.
• This leads to male physical characteristics and
behaviour i.e. “maleness”.
NB: DHT case study below ( page 45 of your booklet).
• Females on the other hand have ovaries which
lead to female characteristics and behaviour
e.g. They produce oestrogen, progesterone
and a small amount of testosterone.
• Many research studies have associated the
role of testosterone with aggression which is
why males are deemed more aggressive than
females.
• This has been supported in research evidence
based on rats, how well can these results be
generalised? Therefore our gonads have a
strong influence on our gendered behaviour.
3.Hormonal sex:
Hormones are your body's chemical messengers. They
travel in your bloodstream to tissues or organs. They
work slowly, over time, and affect many different
processes, including;
• Growth and development
• Metabolism - how your body gets energy from the
foods you eat
• Sexual function
• Reproduction
• Mood
Endocrine system
Endocrine glands, which are special groups of
cells, make hormones. The major endocrine
glands are the pituitary, pineal, thymus, thyroid,
adrenal glands and pancreas. In addition, men
produce hormones in their testes and women
produce them in their ovaries.
Hormones are powerful. It
takes only a tiny
amount to cause big
changes in cells or even
your whole body. That
is why too much or too
little of a certain
hormone can be
serious. Laboratory
tests can measure the
hormone levels in your
blood, urine or saliva.
NB: We all produce the same four main hormones
males produce a lot more androgens the main one
of which is testosterone (from early gestation
onwards) and females do produce a lot more
oestrogen and progesterone although from birth
onwards.
Men produce some amount of progesterone, but it
probably has no normal function except to help
produce other steroid hormones.
4. Sex of the internal reproductive
structures:
• Males have Wolffian ducts which will later
develop into the prostate gland, sperm ducts,
seminal vesicles and testes
• Females have Mullerian ducts that will later
develop into the fallopian tubes, womb and
ovaries
5. Sex of the external genitals:
Males have a penis and scrotum while females
have the outer lips of the vagina (labia majora).
NB; the absence of testosterones in a male leads
to the development female structures.
Clip
Female reproductive system.
Male reproductive system.
Describe the role of hormones and genes in gender
development. (8 marks)
Plan – 1x A4 long
• Use technical terms to describe role of
hormones/genes – testosterone, etc
• Describe two examples of gender disorders
True False
1. Week 9 gestation is important in hormonal
production
2. Testosterone triggers female sexual
development
3. SRY gene makes gonads become ovaries and
womb
4. The Pituitary is in the adrenal glands.
5. Wolffian ducts turn into ovaries/vagina