biological psych Flashcards
What chromosomes determine sex in mammals?
XX (female) and XY (male) chromosomes
The SRY gene on the Y chromosome plays a critical role in determining sex.
What is the role of the SRY gene?
Activates testis development; absence results in ovary development
The SRY gene is located on the Y chromosome.
What hormones are produced by early testes and their effects?
- Anti-Müllerian Hormone: Defeminises
- Androgens: Masculinise
Without these hormones, female sex organs develop.
What are the primary sexual characteristics in males and females?
Internal: Vas deferens (male), uterus (female); External: Dihydrotestosterone (DHT) essential for male genitalia
DHT is crucial for the development of male external genitalia.
What are the organizational effects of hormones?
Occur during critical periods; effects persist after hormone removal
These effects are significant during prenatal development.
What are activational effects of hormones?
Temporary and depend on hormone presence
These effects are observed during puberty.
What triggers the onset of puberty?
Kisspeptin and GnRH; FSH and LH stimulate gonads
This mechanism initiates the development of secondary sexual characteristics.
What are the secondary sexual characteristics developed during puberty?
Androgen-sensitive features: Pubic and axillary hair
These characteristics vary between sexes.
What is Androgen Insensitivity Syndrome (AIS)?
Cause: Non-functional androgen receptors; Outcome: 46,XY individuals develop female anatomy (external)
AIS individuals have no internal female reproductive organs.
Describe the outcome of 5α-Reductase Deficiency.
46,XY children are born with female external genitalia but male internal organs; develop male genitalia at puberty
This condition results from the inability to convert testosterone to DHT.
What is Congenital Adrenal Hyperplasia (CAH)?
Cause: Excess prenatal testosterone in 46,XX individuals; Outcome: Ambiguous genitalia, more masculine traits/behaviours
Some cases may lead to gender dysphoria.
What are the structural differences between male and female brains?
Male brains: ~10% larger; Female brains: Thicker cortex, more grey matter; Males: Larger white matter and subcortical structures
These differences can influence behavior and cognition.
What are some functional differences in behavior between boys and girls?
Different toy preferences; CAH girls exhibit more masculine preferences
These preferences can be influenced by hormonal exposure.
Who excels in spatial rotation tasks?
Men
Performance differences may be linked to prenatal testosterone exposure.
What percentage of males and females are attracted to the opposite sex?
~90% of males are attracted to females (gynophilic); ~85% of females are attracted to males (androphilic)
These statistics highlight common patterns in sexual orientation.
What are some biological correlates of sexual orientation?
Brain differences in SCN, INAH-3, and anterior commissure
These areas are linked to sexual behavior and orientation.
What is the Fraternal Birth Order Effect?
Maternal immune response to Y-linked proteins
This phenomenon is theorized to influence male sexual orientation.
What brain differences are observed in individuals with gender dysphoria?
MtF individuals: Feminine cortical thickness; FtM individuals: Masculine basal ganglia
Brain anatomy in gender dysphoria diverges from both cis males and cis females.
What do twin studies suggest about gender dysphoria and sexual orientation?
Higher concordance in monozygotic twins
This indicates a genetic component to these traits.
What is the impact of environmental and cultural influences on sexual orientation?
Minimal effects; Gendered expectations and stereotypes impact behaviour, not orientation
Social influences can shape behavior but not the underlying orientation.
What are potential explanations for the retention of non-reproductive orientations?
- Heterozygote advantage
- Kin selection
These evolutionary theories explore the adaptive value of diverse sexual orientations.
What factors drive sexual differentiation and orientation?
Biological, hormonal, and genetic factors
These factors are influenced by both organizational and activational influences.
What is appetitive behaviour in the context of sexual behaviour?
lecture 2
Behaviour aimed at finding and obtaining a sexual partner
What is consummatory behaviour?
Behaviour of the actual sexual act
What role do external stimuli play in sexual motivation?
Usually related to opposite-sex conspecifics and can include chemical stimuli such as pheromones
What are pheromones?
Species-typical molecules that trigger a specific response in another animal of the same species
How are pheromones detected in other mammals?
By the vomeronasal organ
Is there a debate about the functionality of the vomeronasal organ in humans?
Yes, there is debate about whether humans have a functional vomeronasal organ
What can the olfactory epithelium in humans detect?
Some pheromones
During which phase of the menstrual cycle do women’s t-shirts smell sexier?
During the fertile phase
What is the effect of androstadienone found in men’s sweat on women?
Triggers alertness, good mood, and sexual arousal in women
What is the effect of estratetraene on male and female hypothalamic areas?
Activates male, but not female hypothalamic areas
What hormones influence sexual interest in males?
Testosterone (T)
What happens to sexual interest when testosterone is suppressed in males?
It reduces sexual interest but not performance
What increases testosterone levels in males?
Anticipation of a sexual encounter
How does sexual interest fluctuate in females?
With cycling ovarian hormones, especially oestradiol
What is the effect of androgens on the effect of oestradiol in females?
Androgens increase the effect of oestradiol up to 3 times
What is the four stages of sexual arousal according to Masters & Johnson?
Excitement, Plateau, Orgasm, Resolution
What nervous system is involved in the excitement and plateau phases of sexual arousal?
Parasympathetic Nervous System
What neurotransmitter is involved in the mechanics of excitement and plateau?
Nitric Oxide (NO)
What does Viagra do?
Inhibits the breakdown of cGMP, keeping the smooth muscle relaxed
What causes erectile dysfunction according to the text?
Always physical, stress leads to increased sympathetic activity causing vasoconstriction
What system triggers orgasm?
Sympathetic Nervous System
What neurotransmitter inhibits orgasm circuitry in the lumbar spinal cord?
Serotonin
What happens to blood oxytocin levels during orgasm?
They peak
What is the role of prolactin released during orgasm?
High prolactin levels suppress sexual motivation
What is concluded about sex steroids in sexual motivation?
They play an important role in sexual motivation
What controls the sexual response?
A reflex arc with modulation by the central nervous system
