Sexual behaviour Flashcards
What is the enzyme aromatase required for?
- The biosynthesis of oestrogens from testoterone
What changes occur to mammals during the reproductive cycle?
- Inititation of sexual encounters increases prior to ovulation
- Areas of flesh exposed by women change throughout cycle
- Some species, sexual attractiveness changes
- Synaptic denstiy in the hippocampus changed in relation to levels of oestrogen
- Synapses more sensitive to excitatory synaptic inout for the labatory
What happens when a cow has a male and a female twin?
- The female is a freemartin
- Behaves like a bull
- Due to being exposed to testosterone in the uterus
- Ovaries don’t develop properly - sterile
What controls the bulbocavernousus muscle?
Motor neurons which lie in the Onuf’s nucleus in the sacral spinal cord
What is different about male and female brains?
- Show sexual dimorphism (structural differences)
- Male brains are larger
- The sexually dimorphic nucleus (SDN) in the pre-optic area of the hypothalamus is larger in males
- Differences in testosterone receptors and aromatase activvity
Describe human sexual arousal processes between the brain and the body.
- Brain feeds into physiologyical effects
- Peripheral arousal system
- Controlled by spinal reflexes and stimulated by thought or touch
- Strong link between brain and body
Why is sexual reproduction confusing?
- Can mistake signals
What are the 3 main sex steroids?
- Progesterone
- Testoterone
- Estodiol
Both males and females have all sex steroids but in different proportions
What is congenital adrenal hyperplasia?
- In females
- Adrenal gland secretes high levels of an androgen in early life
- Ovaries present but external genitalia are indistinct (intermediate between clitoris and penis)
- CAH women often agressive and ‘male-like’
- Possible due to masculinisation of the brain that would normally occur in boys
Why is sexual reproduction expensive?
- High metabolic cost of pregnancy
- Need to raise young so they can look after themselves
- Even unsuccessful reproductive cycles use up huge amounts of energy and effort
What happens if aromatisation of testosterone to estrodiol is blocked?
Causes a build-up of testosterone
What is polyandry?
- One female mate with many males
- BUT, each male mates with just that female
- Rare in mammals
- Occurs in finches (determine quality of sperm and reject lesser)
What is the critical point of development in which exposure to different sex hormones can cause an effect on the organism in later life?
Shortly after birth, during development
What happens when treat female rats with testosterone at birth?
- Prevents lordosis (arching of the back downwards prior to mating) in adulthood
What is estrogen?
An estrodiol (female hormone)
