Chapter 11: Reproductive Behaviours Flashcards
three types of sex hormones and the three ways they can exert their effects
Steroid Hormones-androgens and estrogens
Testosterone
Progesterone
ways sex hormones can exert their effects
Steroid Hormones: androgens and estrogens
- exert effects in 3 ways
1) bind to membrane receptors, rapid effects
2) enter cells and activate certain kind of proteins in cytoplasm
3) Bind to receptors that bind to chromosomes where they activate or inactivate certain genes .
Testosterone
Most common androgen
Estradiol
most common estrogen
Progesterone
prepare uterus for implantation of fertilized ovum and promotes maintenance of pregnancy
Organizing Effects
long lasting structural effects
ie- determine if body develops male or female anatomy in early development
-surge of hormones at puberty
Activating effects
- more temporary
- hormone increase some activity that lasts only while hormone is present
Testosterone
-important in differentiation of external genitals,
high testosterone=male pattern
low testosterone=female pattern
Sensitive Period
-sensitive period=3-4 months of pregnancy
Injecting Rats with sex hormone
- female rat with testosterone injection mounts and humps sexually receptive females
- injecting male with estrogen has little impact on genitals
activating roles of hormones on reproductive behaviors and neurotransmitters in certain brain areas
- sex hormones influence development in parts of hypothalamus, amygdala, and other brain areas
- parts of female hypothalamus generates cyclic pattern of hormone release (menstrual cycle)
- changes in hormonal secretions influence sexual behaviour within 15 minutes
- testosterone=essential for male arousal
- estradiol and projesterone=most effective combo for female
- sex hormones enhance sensations
- estrogen increases sensitivity of pudenal nerve (transmits tactile stimulation from vagina and cervix to brain)
- testosterone increases sensitivity of penis
- testosterone and estradiol prime MPOA and several other areas to release dopamine
- burst of dopamine @orgasm from stimulation of D2 receptors
- high testosterone levels associated with seeking multiple partners
- increase testosterone= increase sexual drive
hormonal processes that control women’s menstrual cycles and pregnancy, including the effects of birth-control pills
-hypothalamus and pituitary gland interact with ovaries to produce menstrual cycle
FSH
-promotes growth of follicle in ovary
LH
-luteinizing hormone
FSH + LH
- follicle release ovum
- see pg. 335 for diagram and description
Effects of Birth Control Pills
- prevents pregnancy by interfearing with feedback cycle between ovaries and pituitary gland
- estrogen and progesterone prevents surge fo FSH and LH so ovum is not released and thickens cervical mucus making it harder for sperm to get to ovum
Oxytocin
- pituitary hormone
- stimulates contradictions of uterus during delivery of baby
- released at orgasm
endocrine influences on parental behaviors.
- role of hormones=less central for humans
- infant rats release chemicals that stiumlate mother’s vomeralnasal organ
- hormones in early phase compensate for mother’s lack of familiarity with young
- hormonal changes are NOT necessary for human parental behaviour ex) adoption- parents can still be excellent
Mother post delivery
- increases secretion of estradiol and prolactin and decreases progesterone
- > milk production
- > retrieving young that wander from nest
- > inhibits leptin sensitivity so mother can eat more
Late pregnancy
-increases sensitivity to estradiol and areas responsible for maternal behaviour
Vasopressin
-important for social behaviour
sexual selection
genes that make an individual more appealing to other sex increasing probability of reproduction
Reasons casual sex
- more men than women seek casual sex with many partners
- evolutionary reasons/strategies
1) loyal to 1 human and devote energy to helping her and babies
2) mate with many women and hope some can raise babies without help
Seeking mates
-seek mate that is healthy, intelligent, honest, and physically attractive
Women seeking mates
-seek good providers so they can get help while taking care of offspring
Men seeking mates
- men have stronger preference to younger partners
- younger partners remain fertile longer
Jealousy
- in most cultures men have been more jealous of women’s infidelities
- evolutionary reason needs to be certain the offspring in his to pass on hi genes
- men=more upset by sexual infidelity
- women=more upset by emotional infidelity
Hermaphrodites
- mixture of male and female
- intermediate appearance due to atypical hormone pattern due to low levels of testosterone
Congenital adrenal hyperplasia
-overdevelopment of adrenal glands from birth
Intersexes
-sexual development is intermediate
Androgen insensitivity/testicular feminization
=individuals with XY chromosome have genital appearance of female
genetic and hormonal influences on gender identity and sexual orientation
- behavioural and anatomical differences between hetero and homo males
- reasonable to infer a genetic contribution to sexual orientation
- hormone levels in adults are nearly the same
- having an older biological brother if man slightly increases homo orientation
- stressful experience during pregnancy
- brain anatomy can be slightly shifted toward female typical (homo men) or male (homo female)
- mean volume of third interstitial nucleus of anterior hypothalamus is larger in hetero men
Hetero males
- taller and heavier than homo
- use distance and direction
Homo
Use landmarks and are better than hetero at remembering landmarks
