Exam 3

control of hormone secretions

hypothalamus

reproductive maturation, body rhythms

pineal gland

hormone secretion by thyroid, adrenal cortex & gonads; growth

anterior pituitary

water & salt balance

posterior pituitary

growth & development, metabolic rate

thyroid

salt & carb metabolism; inflammatory rxns

adrenal cortex

emotional arousal (epinephrine)

adrenal medulla

Neural and hormonal chemical communication differ:

• hormones act in gradual fashion

• Hormones often have pulsatile secretion – in bursts

• Some hormones are controlled by circadian clocks

how do neural & hormonal responses differ in terms of spatial extent?

neural : precise

hormonal: diffuse

short string of amino acids

peptides

modified version of a single amino acid

monoamines (amines)

- derived from cholesterol, made of 4 rings of Carbon

steroids

peptide hormones

amine hormones

steroid hormones

_____ & ____ bind to receptors on the cell surface to activate second messengers.

Peptides and Amines

(metabotropic)

Steroids cross the cell membrane and bind to receptors inside the cell, which act as _______ (control expression of specific genes).

transcription factors

______ cells in the hypothalamus produce and store two hormones which affect social behaviors in the posterior pituitary.

Neuroendocrine

the posterior pituitary secretes two hormones:

• Vasopressin (antidiuretic hormone)- raises blood pressure and inhibits urine formation water conservation, pair-bonds

• Oxytocin- reproductive & parenting behavior (maternal bonding), uterine contractions, milk letdown reflex

The sensory signal from nipple stimulation is sent to the ________, which is routed to the hypothalamus leading to neuroendocrine cells sending action potentials to the_________ to release oxytocin, which contracts mammary glands

somatosensory cortex

posterior pituitary

_____ hormones from hypothalamus control pituitary’s release of tropic hormones

Releasing

_______hormones pituitary hormones that affect other endocrine glands

tropic (trOHpic)

thyroid hormone pathway

1) Hypothalamic neurons synthesize releasing hormones

2) Releasing hormones are then secreted into local blood vessels

3) Releasing hormones float to anterior pituitary, which releases hormones

Vasopressin (antidiuretic hormone (ADH))

raises blood pressure, inhibits urine formation

Emotions, especially fear

oxytocin

maternal behavior / bonding. Autism?

Thyroid hormone contains ________- and depends on its supply

iodine

A _____ is swelling of the thyroid gland from iodine deficiency

goiter

____________ is inadequate thyroid hormone production in newborn infants

Congenital hypothyroidism (CH)

iodine TSH interaction

_______ results from long-term excess glucocorticoids, with fatigue and depression

Cushing’s disease

The hypothalamus controls gonadal hormone production by releasing _______ into the median eminence

gonadotropin releasing-hormone (GnRH)

GnRH stimulates the anterior pituitary to release one or both gonadotropins:

+ follicle-stimulating hormone (FSH)

+ luteinizing hormone (LH)

in males:

the testes sense LH & produce & secrete the _______, a steroid hormone

testes also sense FSH & (do what..)

androgen testosterone

produce sperm

in females:

Ovaries sense FSH, which stimulated the ________

LH stimulates the follicles in the ovary to_________

maturation of egg containing follicles and the secretion of estrogens

rupture releasing the egg and form a corpus luteum to secrete progesterone

Oral contraceptives exerts negative feedback on the hypothalamus, inhibiting _____

GnRH

• Without GnRH, no FSH or LH is released, and the ovary does not release an egg for fertilization.

levels of sex determination:

Chromosomal Sex (XY, XX, XXY, etc.)

Gonadal Sex (testis, ovaries)

Internal Sex Organs (prostate, uterus)

External Sex Organs (penis, vagina)

Brain Sex

Gender Identity

Gender Preference

Developmental event that decides whether embryo will be male or female gonadally:

SRY gene – sex-determining region on Y chromosome – is responsible for development of testes

Without an SRY gene, an ovary forms

_____ Direct Sexually Differentiation

Gonadal Hormones

____ effects mostly occur prenatally or shortly after birth

Organizing

• They affect brain and body structure and are lifelong (e.g., genitals)

____ effects occur at any time in life

Activating

• Come/go with hormone fluctuation or are long-lasting, but reversible (e.g., muscle mass, breast development, hair growth)

_____ is main organizing hormone in human brain development

Testosterone

In females, the______ develop into the fallopian tubes, the uterus, and vagina—the ______ shrink.

müllerian ducts

wolffian ducts

in males, testosterone promotes the______ to develop into the epididymis, vas deferens, and seminal vesicles, while _______ directs the müllerian ducts shrink.

wolffian ducts

Anti-müllerian hormone (AMH)

Deficiency in an enzyme 5-α-reductase, which is needed to convert testosterone into dihydrotestosterone (imp for development)

~12 yrs old testosterone surge leads to growth of penis

XY

guevedoces

Signs/Symptoms vary, but often patients with Klinefelter Syndrome have low levels of testosterone

Testosterone Replacement Therapy (TRT) during puberty can increase fertility and reverse many signs

chromosomes: ____

XXY

Why do individuals engage in reproductive behavior?

Reproduction (more of us)

DNA shuffling (but not exactly us)

It’s fun (uniquely human- no)

how is sex like hunger & thirst?

• involves arousal & satiation

• hormonal control

• controlled by specific areas of the brain

sex is unlike hunger & thirst:

• not homeostatic tissue need

• individuals don’t require rex for survival (species do)

Gonadal steroids ____ sexual behavior

activate

Estrogen rise before ____ promotes non-human sexual behavior

ovulation

If a female is sexually receptive she is in ____

estrus

human females don’t have estrus – they are complicated (but they are more likely to initiate sex at ovulation)

human sexual response curve

in both men & women:

1. excitement phase (arousal)

2. In plateau, arousal levels off

3. Orgasm (ejaculation)

4. Resolution, as arousal falls and body returns to normal

_____ Are Necessary for Male Copulation

Androgens

PET imaging of male orgasm shows that primary activation was in …..

ventral tegmental area

Oxytocin releases at ejaculation; promoting bonding?

PET imaging of female orgasm shows activation & inhibition of what?

• Activation of the deep cerebellar nuclei

• Inhibition of orbitofrontal cortex

• higher lvl decision making is dampened (animal brain)

Medial amygdala (MeA; in the temporal lobe)

Involved in sex, smell, aggression, and emotions

Medial preoptic area (mPOA of the hypothalamus)

involved in sexual performance

brain areas for sex important for males:

• Sexually dimorphic nucleus

  • Located in mPOA (INH3 in humans) (anterior hypothalamus)

  • 2-3x larger in men

  • Male sex activity related to its size

  • Size depends on prenatal exposure to testosterone

brain areas important for sex in females:

ventromedial hypothalamus

(Receptivity to male advances; ‘in the mood’ Increases dendritic trees in response to estrogen)

dopamine (DA) activity in ____ motivates sex behavior in both sexes, esp. in men

• Drugs that increase DA increase sexual activity in humans

• Increasing levels of DA produce erection in males, then ejaculation

mPOA

serotonin (5HT) increases in the _______ during ejaculation- contributing to the refractory period?

• Injecting SSRI into LH increases time before male rats copulate again

• Both men and women complain SSRIs impair their sexual ability

lateral hypothalamus

T/F: women have larger corpus callosum

TRUE

size of corpus callosum correlates with cognitive skills in women

T/F: males have greater asymmetry than females

• right hemisphere is _____ in males than females

TRUE

thicker

Women have greater gray matter in….

dorsolateral prefrontal cortex (think before you act) • superior temporal gyrus (talking/listening)

overall, males have

1. ______ inferior parietal lobule, amygdala, nucleus of anterior hypothalamus, bed nucleus of stria terminals

2. ______ Broca’s area & Wernicke’s area, anterior commissure, hippocampus

1. larger

2. smaller

how do sexual dimorphisms develop?

prenatal hormone exposure or social influence

The _________ was larger in men than in women, and larger in heterosexual men than in gay men

Interstitial Nuclei of the Anterior Hypothalamus

little support for _______, which emphasizes home environment or early seduction as causes of homosexuality

social influence hypothesis

_____ influences- The likelihood that an individual identifies as gay or lesbian is 2-7 times higher among siblings of gay and lesbians than in general population

Genetic

Gay men and heterosexual men have the _____testosterone levels (as adults)

same

Any hormonal influence on a man sexual orientation likely occurs _____

prenatally

Women who identify as lesbians later in life have been shown to have had ____ exposure to fetal androgens than those identifying as heterosexual

more

____ hypothesis- The more older brothers a man has from the same mother, the greater the probability he will identify as being gay, (but only if R handed) - Maternal antibodies to make tissues

Antibody

label 1,2,3

1. Bed nucleus of the stria terminalis

2. Sexually dimorphic nucleus (INAH3)

3. Suprachiasmatic nucleus

T/F: gay men have a larger third interstitial nucleus of the anterior hypothalamus

FALSE

it is female sized (smaller)

_______ is larger in gay men than in heterosexual men and contains more vasopressin-secreting cells

Suprachiasmatic nucleus (SCN)

_______ is larger in gay men and heterosexual women than in heterosexual me

Anterior commissure (AC)

Larger Right Hemispheres in both ___________________

Symmetric Hemispheres in both _______________

lesbians and heterosexual males

gay males and heterosexual women

Spatial ability is affected by _______________

masculinization

High estrogen level is associated with

• depressed spatial ability

• enhanced speech and manual skill tasks

_______ during 2nd trimester increases cerebral asymmetry via accelerated growth of the right hemisphere

Testosterone

Males low in testosterone in development are impaired in ________________

spatial ability

the maintenance of a stable, balanced, internal environment

homeostasis

___________ systems are the main homeostatic mechanisms

If a desired set point is deviated from, compensatory action begins

negative feedback

factors that initiate, sustain, or direct behavior

motivation “to set in motion”

_______- drive physiological motivation

Homeostatic systems

what are the two internal cues that trigger thirst?

1. low volume (hypovolemic thirst)

   1. replenish systems

      detected by brain, kidney, heart

2. high [solute] (osmotic thirst)

______ is the principal fuel for energy

Glucose

_____ is glucose stored for short term in the liver

Glycogen

______: converting glucose to glycogen, using pancreas hormone insulin

Glycogenesis

____, for long-term storage, are stored in fat tissue

Lipids

T/F: Brain integrates insulin and glucose levels with other information to decide when to start/stop eating

true

Fat cells produce _____ and secrete it into the bloodstream

leptin

Defects in leptin production or receptor sensitivity give a falsely ____(low or high) report of body fat, causing animals to overeat

low

Obese people are leptin-…..

resistant

Overnutrition inflames the _______ - obesity, diabetes, and heart disease

hypothalamus

Released by stomach endocrine cells

-  Appetite stimulant

Rises during fasting; drops after eating

ghrelin

leptin & ghrelin before vs after eating

Ghrelin levels are _________ in Prader-Willi

elevated

___________ usually caused by deletion of a part of chromosome 15.

Defects in the hypothalamus.

Prader-Willi