Chapter 10: Sexual And Reproductive Behaviors Flashcards
Sexual Dimorphic Behavior
Behavior that has different forms or that occurs with different probabilities or under different circumstances in males and females
Sex
Genetic or physiological characteristics of males and females
Gender
Refers to socially- influenced identity, roles, and/or behavior of individual as they pertain to male and female identities
Intersex
Variety of combos of biologically male and female characteristics, such as individual born with external female genitalia and internal male sex organs
Transgender
Gender identity that does not necessarily correspond to biological sex at birth
Gametes
Mature reproductive cell (sperm or ovum)
- Produced during cell division process called meiosis
- Produces cells that contain one set of each of pairs of chromosome
Genetic Sex
Determined by presence of XX or XY chromosome
- determined at time of fertilization
Sex Chromosomes
X and Y chromosomes, which determine an organism’s genetic sex
Exposure to sex hormones, […], is responsible for much of […]
Exposure to sex hormones, both before and after birth, is responsible for much of sexual dimorphism
3 categories of sex structures
Gonads
Internal sex organs
External genitalia
Gonads
- Testes and ovaries; first sex organs to develop
- Produce ova or sperms and secrete hormones
- Through 6th week of prenatal development, male and female fetuses are identical
- Both sexes have pair of identical undifferentiated gonads
SRY
Gene on Y chromosome whose product instructed undifferentiated fetal gonads to develop into testes
- absence of gene produces ovaries
Organizational Effect
Effect of hormone on tissue differentiation and development
- Permanent and persist throughout person’s life
Activational Effect
Effect of hormone that occurs in fully developed organism
- Occur later in life - May depend on organism’s prior exposure to organization of hormones
Wolffian System
Epididymis, vans deferents, seminal vesicles
- Testes secrete two types of hormones:
- Anti-Mullerian Hormone
- Androgen
Anti-Mullerian Hormone
Peptide secreted by fetal testes that inhibits development of
Mullerian system, which would otherwise become female internal sex organs
- Defeminizing Effect
Defeminizing Effect
Effect of hormone present early in development that reduces or prevents later development of anatomical or behavioral characteristics typical of females
Androgen
Male sex steroid hormone (testosterone and dihydrotestosterone)
- Masculinizing Effect
Masculinizing Effect
Effect of hormone present early in development that promotes later development of anatomical/ behavioral characteristics typical of males
Androgen Insecurity Syndrome
Condition caused by congenital lack of functioning androgen receptor
- In person with XY sex chromosomes, causes development of female with testes but no internal sex organs - Androgens don’t have Masculinizing effect - Anti-Mullerian hormone has defeminizing effect, preventing female internal sex organs from developing
Persistent Mullerian Duct Syndrome
Condition caused by congenital lack of anti-Mullerian hormone or receptors for this hormone
- In male, causes development of both male and female internal sex organs - Androgens have their masculinity effect, but defeminization does not occur
Turner Syndrome
Presence of only one sex chromosome (X chromosome)
- Lacks ovaries but otherwise normal female sex organs and genitalia
External Genitalia
Visible sex organs:
- Males: penis and scrotum - Females: labia, clitoris, and outer part of vagina
In presence of dihydrotestosterone, male external genitalia develops
- Female sex hormones are not required for female genitalia development - Development of person’s external genitalia is determined by presence/ absence of androgen
Primary Sex Characteristics
- Influences by organizational effects of hormones
- Present at birth; includes gonads, internal sex organs, and external genitalia
Secondary Sex Characteristics
- Influenced by activational effects of hormones
- Develop during puberty
- Puberty triggers hypothalamus to secrete gonadotropin-releasing hormones
Gonadotropin- releasing hormones (GnRH)
Hypothalamic hormone that stimulates anterior pituitary gland to secrete gonadotropic hormone
Gonadotropic Hormone
Hormone of anterior pituitary gland that has stimulating effects on cells of gonad
- Follicle-stimulating hormone (FSH) - Luteinizing hormone (LH)
Follicle-stimulating hormone (FSH)
Hormone of anterior pituitary gland that causes development of an ovarian follicular and maturation of ovum
Luteinizing Hormone (LH)
Hormone of anterior pituitary gland that causes ovulation and development of ovarian follicle into corpus luteum
Secretion of […] is under control of […]
Secretion of GnRH is under control of kisspeptin
Kisspeptin
Peptide produced by neurons in accurate nucleus of hypothalamus under control of leptin receptors
- essential odor initiation of puberty and maintenance of reproductive ability
Gonads secrete sex hormones
Estradiol
Estrogen
Estradiol
Principle estrogen of many mammals, including humans
Estrogen
Class of sex hormones that cause maturation of female genitalia, growth of breast tissue, and development of other physical features characteristics of females
Menstrual Cycle
Female reproductive cycle of most primates
- characterized by growth of lining of uterus, ovulation, development of corpus luteum, and menstruation
Estrous Cycle
Female reproductive cycle of mammals other than primates
Menstrual cycle begins with secretion of gonadotropins by […], which stimulates growth of […]
Anterior pituitary, ovarian follicles
Ovarian follicles
Cluster of epithelial cells surrounding an oocyte, which develops into ovum
What happens as follicles mature
They secrete estradiol, causing lining of uterus to develop
What happens when estradiol reaches a critical level?
Causes pituitary gland to release LH, triggering ovulation
LH surges cause […]
Ovulation: ovarian follicle ruptures, releasing ovum
Under continued influenced of LH, ruptured follicles becomes […] which produces […]
Corpus luteum; estradiol and progesterone
Corpus luteum
Cluster of cells that develops from ovarian follicles after ovulation
Progesterone
Steroid hormone produced by ovary that maintains endometrial lining of uterus during later part of menstrual cycle and during pregnancy
- Maintains lining of uterus and it inhibits ovaries from producing another follicle
Refractory Period
Period of time after particular action (ex. Ejaculation by male) during which that action cannot acute again
Coolidge Effect
Restorative effect of introducing new female sex partner to male that had apparently become “exhausted” by sexual activity
Oxytocin
Hormone secreted by posterior pituitary gland - Causes contraction of smooth muscle of milk ducts, uterus, and male ejaculatory system
- Produced in males, where it plays no role in lactation
Estrus
Period of sexual receptivity in many female mammals (excluding humans)
Lordosis
Spinal sexual reflex seen in many 4-legged female mammals
- Arching of back on response to approach of male or to touching flanks, which elevates hindquarters
[…] increases just before receptivity occurs and […] begins secreting large quantities of […] —> […]
Estradiol increases just before receptivity occurs and corpus luteum begins secreting large quantities of progesterone —> results in sexual receptivity
Sequence of estradiol followed by progesterone has 3 effects on female rats
- Receptivity
- Proceptivity
- Attractiveness
Receptivity
Female’s ability and willingness to copulate by displaying lordosis when male attempts to mount her
Proceptivity
Female’s interest in copulation, as shown by seeking out male and engaging behaviors that tend to increase his sexual interest
Attractiveness
Physiological and behavioral changes in female that affect physiological and behavioral changes in female that affect male
Behavioral Defeminization
Organizational effect of androgens that prevents animals from displaying female sexual behavior in adulthood
Behavioral Masculinization
Organizational effects of androgens that enables animals to engage in make sexual behavior in adulthood
Activational Effects of Sex Hormones in Women
- Ovarian hormones influence women’s sexual interest, behavior, and physiology
- Sexual interest can also be stimulated by androgens (from ovaries and adrenal glands)
- Women were more likely to initiate sexual activity and more likely to engage in sexual fantasies just before and during surge in LH that stimulates ovulation
Activational Effects of Sex Hormones in Men
- Testosterone has activational effect on sexual behavior of men
- Sperm production and sexual interest ceases without testosterone
- Testosterone is also affected by sexual activity or by thinking about it
Pheromone
Chemical released by one animal that affect behavior or physiology of another animal
- Detected by VMO
- Can influence menstrual cycles. mood, and changes in attractiveness rating and brain activity
Vomeronasal Organ
Sensory organ that detects the presence of certain chems, especially when liquid is actively sniffed; mediates effects of pheromones
- Contains over 200 GPCR molecules
Accessory Olfactory Bulb
Neural structure located in main olfactory bulb that receives info from VNO
Lee-Boot Effect
The slowing and eventual cessation of estrous cycles in groups of female animals that are housed together
Whitten Effect
The synchronization of menstrual or estrous cycles of group of females, which occurs only in presence of pheromone in male’s urine
Vandenbergh Effect
Earlier onset of puberty seen in female animals that are housed with males
Bruce Effect
Termination of pregnancy caused by odor of pheromone in urine of male other than one that impregnated female
Male Sexual Behavior
Erection and ejaculation are controlled by neurons in spinal cord
- spinal ejaculation generator - brain mechanisms have both excitatory and inhibitory control
*review circuit
Stimulating the […] elicits copulatory behavior; destroys it abolishes behavior
Stimulating the medial preoptic area (MPA) elicits copulatory behavior; destroys it abolishes behavior
Medial preoptic area (MPA)
An area of cell bodies just rostral to hypothalamus
- plays essential role in male sexual behavior - mating increased release of Glu in MPA - Infusion of Glu into MPA increased frequency of ejaculation - Destruction of MPA abolishes male sexual behavior
Sexual Dimorphic Nucleus
Nucleus in preoptic area that is much larger in males than in females
Most important connections between MPA and motor neurons of spinal cord are accomplished through […] of midbrain and […] of medulla
Periaqueductal gray (PAG) Nucleus paragigantocellularis (nPGi)
Periaqueductal gray (PAG)
Region of midbrain that surrounds cerebral aqueduct
- plays on essential role in various species-typical behaviors - including female sexual behavior
Nucleus paragigantocellularis (nPGi)
Nucleus of medulla that receives input from MPA (which suppresses activity) and contains neurons whose axons from synapses with motor neurons in spinal cord that participate in sexual reflexes in males
Female Sexual Behavior Mechanism
*draw out
Ventromedial nucleus of hypothalamus (VMH)
Large nucleus of hypothalamus located near walls of 3rd ventricle
- plays essential role in female sexual behavior
Lordosis neural pathway
VMH—> PAG —> nPGi —> motor neurons in ventral horn of lumbar region of spinal cor
Orgasm in women
Activation in junction between midbrain and diencephalon, lateral putamen, and cerebelllum
[…] and […] peptides facilitate pair bonding
- Male voles: vasopressin plays major role
- Female voles: oxytocin plays major role
- Both are important in human pair bonding
Mating induced production of […] protein in […]
Mating induced production of Fos protein in ventral forebrain
Male pair bonding
- Monogamous voles have higher level of V1a vasopressin receptors
- Blocking V1a receptors diminishes pair bonding
Female pair bonding
- Mating stimulates release of oxytocin
Human pair bonding
- Increase in oxytocin after intercourse
- Feelings of calmness and well-being
Gay/ Lesbian
Having emotional, romantic, or sexual attractions to members of one’s own sex
Bisexual
Having emotional, romantic, or sexual attraction to both men and women
Heterosexual
Having emotional, romantic, or sexual attractions to members of other sex
Roles of Activational and Organizational Effects of Hormones in Sexual Orientation
- Sexual orientation is not strongly related to variation in sex hormone levels in most adults (activational effects)
- Stronger evidence for organizational effects of hormones in sexual orientation
- 5A-reductase deficiency syndrome —> plays role in gender identity and sexual orientation
Congenital adrenal hyperplasia (CAH)
Condition characterized by hypersecretion of androgens by adrenal cortex
- females, causes masculinization of external genitalia
- girls with CAH are born with enlarged clitoris and partially fused labia
- females have higher rate of gay/lesbian orientation
- Nonclassical CAH- typical female genitalia at birth and do not show signs of increased androgen levels until late childhood or adolescence
Brain sexual dimorphism
Differences in corpus callosum, hippocampus, amygdala, hypothalamus, PFC, and throughout several neuroendocrine systems
Brains of gay and heterosexual men and women show differences in dimorphism structures
- Suprachiasmatic nucleus (SCN)
- Sexually dimorphic nucleus of hypothalamus
- Anterior commissure
Neurons in […] send axons to […], which is related to gender identity
Neurons in urnicate nucleus send axons to BNST, which is related to gender identity
Nest-building behavior is facilitated by […]
Nest-building behavior is facilitated by progesterone
Parturition
Act of giving birth
[…] facilitate maternal behavior
Progesterone, estradiol, and prolactin
Prolactin
Hormone of anterior pituitary gland, necessary for production of milk
- also facilitates maternal behavior
[…] also facilitates onset of maternal behavior
Oxytocin
Male Sexual Behavior: Serotonin connections
men who take SSRIs have no trouble attaining an erection but have difficulty achieving an ejaculation
[…] plays a role in maternal behavior
medial preoptic area
Sexual dimorphism of the […] is less pronounced in voles of monogamous species
Sexual dimorphism of the MPA is less pronounced in voles of monogamous species
