PSYC 210: HORMONES AND SEX / HOMEOSTATIS PT I

Types of chemical communication

synaptic

endocrine

pheromone

allomone

synaptic

chemical release and diffusion across synapse

endocrine

glands release hormones, chemicals that travel through the bloodstream, to act on target tissues within the body

pheromone

chemicals released outside the body to affect other individuals of same species

allomone

chemicals released outside the body to affect individuals of another species

Peptide hormones

short string of amino acids (corticotropin-releasing hormone CRH)

Amine hormones

modified version of a single amino acid (monoamine hormones)

Steroid hormones

derived from cholesterol

Three types of steroids

estrogen

progestins

androgens

Two mechanisms of hormone action

protein and amine hormones

steroid hormones

Reproductive behavior

sexual attraction and desire

arousal

copulation and orgasm

resolution

Stage 1: Sexual attraction and desire

species specific

shaped by social and cultural factors

may be synchronized with fertility

preceptive behaviors

Women find what most attractive about men?

symmetrical faces

When do men rate the scents of women the most attractive?

During fertility

Two components of sexual arousal

physiological response of sex organs

subjective perception

Spinal reflex

dopamine may increase sexual motivation and stronger instigation of action

Men treated with levodopa displayed elevated what when show erotic film?

t-reflex

Male rates showed stronger instigation of sexual action following what?

elevations of dopmaine

fMRI studies showed what in both men and women?

VTA activation

What does copulation involve?

One or more intromissions

refractory phase

For males, what follows after an orgasm?

an absolute refractory phase

For females, what follows after an orgasm?

women have diverse copulation and orgasm sequences (highly varied)

What is crucial to the lordosis response?

steroid action on the ventromedial hypothalamus

What does estrogen do in the VMH?

stimulates progesterone receptor production, which helps mediate lordosis

increases dendritic trees of neurons

What steroids is crucial to the lordosis response?

estrogen and progesterone

VMH → Periaqueductal grey → ?

spinal cord

For female rats, what happens in the spinal cord

sensory information from mounting male will evoke lordosis in a female rat in estrus

What is male arousal activated by?

pheromones detected by the vomeronasal organ (VNO)

Female rats: VNO → ? → medial preoptic area (mPOA)

media amygdala

Which hormones acts on the mPOA and media amygdala?

testosterone

Which hormones is necessary for sexual behavior?

testosterone

What reduces copulatory scores?

castration

What recovers copulation?

testosterone treatment

Testosterone exerts an activation effect on what?

sexual behavior

Male rats: ? → ventral midbrain → spinal cord

mPOA

What steroids have an activational effect on sexual behavior?

androgens and estrogens

What hormone must be in circulation to activate typical mating behavior in men?

testosterone

A low dose of testosterone can do what?

restore sexual interest and activity in men and women

Do larger doses of testosterone increase sexual intensity?

no

Same steroids that masculine developing genitalia also masculinizes what other part of the body?

the brain

When are the steroids that masculinize the body effective?

only when present during a sensitive period in early development (before birth or just afterward in neonatal period)

Sexual differentiation

early process in which a fetus begins to develop a male or female body and behaviors

When do indifferent gonads begin to differentiate?

1-2 months

SRY gene

sex determining region on the Y chromosome that is responsible for development of testes

Two hormones from testes that masculinize the system

testosterone

anti-mullerian hormone (AMH)

What does testosterone promote?

development of the wolffian system

Anti-mullerian hormone (AMH)

induces regression of the mullerian system

5a-reductase-enzyme

converts testosterone into the more powerful dihydrotesterone (DHT)

dihydrotesterone (DHT) is required for what?

male genitalia masculinization

What do wolffish ducts develop into for males?

epididymis

vas deferens

seminal vesicles

Which ducts shrink for males?

mullerian ducts

What ducts develop fallopian tubes, the uterus, and vagina for females?

mullerian ducts

Wolffian ducts shrink for females or males?

females

Reduce androgen signaling can block what of the body?

masculinization

Androgen insensitivity syndrome

when an XY fetus has a defective gene for the androgen receptor (still have SRY gene)

For AIS, what doesn’t response to circulating testosterone?

embryo tissues

For AIS, what happens to the testes?

they remain internal

For AIS, what happens externally?

develop as female

For AIS, what happens during puberty?

develop breasts (but no internal female organs)

Turner’s syndrome

person only has one sex chromosome

Do people develop as male or female if they have turner’s syndrome?

female

Congenital adrenal hyperplasia (CAH)

causes developing females to be exposed to excess of androgens before birth

What happens to newborns if they have CAH?

they will have normal ovaries, but no testes

Sexual dimorphism

marked differences in appearance between males and females

In rats, the sexually dimporhic nucleus of the POA in the hypothalamus is larger in males or females?

males

Lesions in the POA (SDN-POA) disrupt what?

ovulatory and copulatory behaviors

When is the sensitive period of the SDN-POA?

around birth

The interstitial nuclei of the anterior hypothalamus (INAH-3) is larger in women or men?

men

Is the INAH-3 larger in gay men or straight men?

straight men

Lesbians on average were exposed to slight more what than straight women?

more fetal androgens

fraternal birth order effect

the more older brothers a right-handed boy has, the more likely he is to grow up gay (thought to be an influence of immune system on fetus)

Two possible influences on gender identity and sexual orientation

biology

socialization

homeostasis

maintenance of a stable, balanced, internal environment

negative feedback

monitoring output and reducing activity when a set point is reached

allostasis

behavioral and physiological adjustments to maintain optimal functioning of a regulated system (adjustments are not to maintain a set point)

Ectotherms

get more of their heat from environment

endotherms

generate their own heat through internal processes

heterotherms

can change between ends and ectothermy

Receptors for thermoregulatory systems

skin surface

body core

hypothalamus (POA)

Neural regions for thermoregulatory systems

spinal cord

brainstem

hypothalamus (POA)

Effectors for thermoregulatory systems

behavioral (shivering, heat seeking)

physiological (sweating, respiration, thyroid hormone secretion, constriction or dilation of blood vessels)

Preoptic are (POA)

mediates physiological responses to cold

Lateral hypothalamus (LH)

mediates behavioral regulation of temperature

The body’s water is actively balanced between which two major compartments?

intracellular

extracellular (blood plasma and intertitial fluid)

Diffusion

molecules of a substance move until a uniform concentration is achieved

osmosis

passive movement of solvent through a semipermeable membrane between solutions of different solute concentration until both sides become equal

sources of fluid loss

perspiration

respiration

urination

When does osmotic thirst occur?

when extracellular fluid becomes too salty

Obligatory water loss

volume of extracellular fluid decreases

solute concentration increases

Eating salty foods can concentrate what?

extracellular fluid

When water is drawn out of cells by osmosis…

loss of intracellular water triggers osmotic thirst

What are the two hormones that target kidneys

vasopressin (antidiuretic hormone)

aldosterone

Vasopression

released from posterior pituitary gland

retain water

slows urine production by increasing reabsorption

aldosterone

released from adrenal gland

retain Na+ from adrenal

stimulate salt appetite

Extracellular fluid indicates the state of what?

intracellular solute concentrations or very salty fluids

What monitors the concentrations of extracellular fluid?

Osmosensory neurons of the hypothalamus and in the OLVT

What is triggered by a loss of fluid volume?

hypovolemic thirst

After baroreceptors detect initial drop in blood pressure…

heart decreases secretion of marital natriuretic peptide (ANP)

When the posterior pituitary steps up to release vasopressin…

induces blood vessel constriction and slows production of urine

With decreased blood volume…

kidneys trigger production of angiotensin II