Lecture 24- Sex and sexuality Flashcards
How is sex genetically determined?
- XX= females -XY= male
What gene on the Y chromosome determines male development?
-there are few genes on the Y chromosome -SRY gene determines this -SRY leads to development of testosterone secreting cells in early development
What does absence of SRY result in?
-female phenotype (this is the default phenotype)
What are the sex hormones (3)?
- Testosterone= (androgen) male sex hormone 2. Estradiol (estrogen)=female sex hormone 3. Progesterone (other main female sex hormone)
What is the pathway by which sex hormones are made?
-
What is really important for sex hormone production?
-presence of cholesterol
What does aromatose do?
-converts testosterone to estradiol (estrogen)
What is 5-alpha dihydrotestosterone?
-converted by 5-alpha reductase from testosterone -stronger type of the androgen
When do sex steroids appear in males?
-In males, circulating testosterone seen early in foetal development – Falls to very low levels after birth – Rises again at puberty
When do sex steroids appear in females?
-In females, circulating estrogen and progesterone appear at or around puberty – Fall to very low levels at menopause – Testosterone synthesized in adrenal cortex- present throughout life
What does testosterone do in females after menopause?
as the other hormones in females disappear from 45-55 -then testpsterone takes up the function of the steroid hormones tp keep the whole system functioning
What is the difference between males and females in presence/absence of sex steroids in utero?
males have testosterone and some and progesterone circulating
When is testosterone the highest in males?
-higheset at 20 and falls to a third by 75
What are the sites of estrogen action in a rat brain?
–At synapses, membrane action –In cell bodies, DNA transcription, estrogen receptors (ER)
What are the effects estrogen in the brain?
-alter neurotransmitter synthesis, releaser and re-uptake -alter membrane permeability -promotes or inhibits transcription (protein synthesis)
How is PMS mood explained?
-estrogen and progesterone and testosterone can act on cell membrane directly= this is likely to account for the mood of PMS!!!! -alter the action of GABA receptors
What are the brain areas with estrogen receptors?
-Most regions with ER involved in sexual behaviour or regulation of steroid production
Are the androgen and progesterone receptors found in overlapping but distinct regions?
-yes -similar subcellular sites of action
How does hypothalamus come into sex steroids?
-sets their levels by feedback •Hypothalamus acts to cause release of hormones (FSH, LH) from the pituitary that regulate production of estrogen or testosterone •Hormone secretion depends on environment and levels of the relevant sex steroid -at this level the hormones have neural effect as it has feedback!
Can sex steroids get through the blood brain barrier?
-yes as they are steroids= lipid soluble
What are the gender dimorphisms in humans? (4)
- Sexual behaviour 2. Pain 3. Cognitive function 4. Maternal behaviour
What are the differences in sexual behaviour between the genders?
- – Mating,courtship,bonding,rhythms
- rats=females get into position for sex if injected with testosterone then try to mount instead= must be hormone mediated
What is stress-mediated analgesia?
if you stress an animal they feel pain less= males and females have different versions and are different pharmacologically
How do females and males differ in cognitive function?
1.Males score better than females on spatial rotation tasks 2.Males score higher, and lower, than females on tests of higher mathematical skills (at low end of mathematical skills= more males than females -females have a tighter grouping around the mean) 3. Females perform better in learning during period after puberty
