NSC 3361 EXAM 3

What is a peptide hormone?

amino acid chain

What is a monoamine hormone?

single amino acid

What are steroid hormones derived from?

cholesterol

How is hormonal communication different from neural communication?

long distance

longer time

graded diffusion (like graded potential)

what does it mean if communication is pulsatile?

occurs in bursts (hormonal)

Which type(s) of hormones activate secondary messengers?

peptide and monoamine hormone

Which type(s) of hormones go inside the cell to bind to a transcription factor?

steriod hormone

- passes through cell membrane

What do neuroendocrine cells do?

cells with neural input with hormonal output

What two hormones are relased by the posterior pituitary?

vasoporessin

oxytocin

-synthesized in hypothalamus

what does vasopressin do?

promotes reabsorbtion of water in kidneys and constricts blood vessels

-used to keep water in the body

-used when low volume of water or high volume of salts

-also known as antidiuretic hormone (ADH)

what does oxytocin do?

Milk letdown, uterine contractions, promotes reproductive and parenting behavior

Neuroendocrine cells located in what area of the hypothalamus synthesize vasopressin and oxytocin?

supraoptic and paraventricular nuclei

What is the mammary gland secretion pathway?

stimulation

somatosensory

hypothalamus

neuroendocrine

posterior pituitary

oxytocin to mammary glands

What are releasing hormones?

stimulation of anterior pituitary hormones

-released by the hypothalamus

What is a tropic hormone?

hormones that act on other endocrine glands

-released by the anterior pituitary

Where are tropic hormones synthesized?

anterior pituitary

How is negative feedback seen with thyroid stimulating hormone (TSH)?

TSH stimulates thyroid -> hormones released by thyroid inhibit TSH

what is a goiter?

enlargement of the thyroid gland from iodine deficiency

-continued TSH production due to no negative feedback

What is congenital hypothyroidism?

thyroid hormone deficiency at birth

results from lower amounts of releasing hormone (TRH) or tropic hormone (TSH)

What is Cushing's disease?

excess glucocorticoid (like cortisol) that leads to fatigue/depression/weight gain

what can excess testosterone lead to?

strength, rage, anger

What is a gonadotropic hormone?

hormone that acts on gonads

What hormone is released from the hypothalamus to stimulate the secretion of FSH and LH?

Gonadotropin releasing hormone (GnRH) into median eminence (connection between hypothalamus and anterior pituitary)

What is the effect of FSH and LH in men?

Testes react to LH to produce testosterone

Testes react to FSH to produce sperm

What is the effect of LH in women?

LH stimulates follicles to release egg, form corpus leteum and secrete progestrone

What is the effect of FSH in women?

ovaries sense FSH which stimulates egg (with follicle) maturation and secrete estrogen

How do oral contraceptives work?

inhibit GnRH by activating negative feedback early

-less LH secretion leads to no egg release

What are the 7 levels of sex determination?

Chromosomal sex

Gonadal sex

Internal Sex organs

External sex organs

Brain sex

Gender identity

Gender preference

WHat does the SRY gene determine?

if someone will be male [Sex determining Region - Y gene]

-only on the Y chromosome, so women do not have this

What is an organizing effect?

differentiation that occurs prenatal/shortly after birth (genitals)

what is an activating effect?

hormone induced effects that can happen at any time and are reversible (hair, muscles, sperm/breast development, sexual interest)

In prenatal women, the lack of the SRY gene causes the ____ ducts to develop and the ____ ducts to shrink

mullerian, wolffian

In prenatal men, the SRY gene causes the ____ ducts to develop and ____ hormone is released to shrink the ____ ducts.

wolffian, anti-mullerian, mullerian

Wolffian ducts develop into what structures?

epididymis, vas deferens, seminal vesicles

-mostly internal structures

Mullerian ducts develop into what structures?

Fallopian tupes, uterus, vagina

what does anti mullerian hormone do?

degenerates mullerian duct

What causes young women in the Dominican republic to turn into men?

congential 5-alpha-reductase deficiency leads to lack of dihydrotestosterone (DHT) during development

-born with XY, wolffian ducts inside but vagina outside

-puberty leads to testosterone surge, forming male genitals despite being female presenting before

what does 5 alpha reductase do?

converts testosterone to dihydrotestosterone

What does congenital mean?

present at birth

What causes Klinefelter syndrome?

extra x chromosome (XXY)

What disorder creates mixed male/female characteristics, osteoporosis, lower fertility, and small testes.

klinefelters syndrome

what can combat symptoms of klinefelters?

testosterone replacement therapy

-increase fertility and reverse female signs

what is estrus?

period of sexual receptivity and female initiated sexual behavior

-estrus is not in humans

What hormone is in high concentration at the time of ovulation/estrus?

estrogen

Lack of what hormone in men leads to less sex?

testosterone

-deficiency can result from castration

What are the 4 phases of the sexual response curve?

Excitement

Plateau

Ejaculation

(refractory period for men only)

Resolution

What part of the sexual response curve is only in men?

refractory period

What does the lack of a refractory period in the sexual response curve women mean?

can experience multiple orgasms quickly

what is the function of the orbitofrontal cortex?

decision making with context

Why are studies about sex not fully conclusive?

studies are mostly correlative, not causative.

-different areas excited/inhibited leading up to orgasm

-men also inhibit some areas

What area of the brain controls reproductive behavior in both sexes?

Medial amygdala (MeA)

Medial preoptic area (mPOA)

Where is the medial amygdala (MeA) and what does it control?

located in the temporal lobe

controls sex, smell, aggression, emotions

Where is the medial preopitc area (mPOA) and what does it control

located in the hypothalamus

controls sexual performance (contains INH3)

What part of the hypothalamus is larger in men and controls sexual activity?

INH3, sexually dimorphic nucleus

-larger size is related to sexual activity

Prenatal testosterone levels can impact the size of what part of the hypothalamus?

INH3, sexually dimorphic nucleus

-more testesterone leads to larger size (2-3 times larger in men)

-organizing effect

INH3 is (larger or smaller) in gay men.

smaller

What part of the hypothalamus is important for women for reproductive behavior?

ventrolmedial hypothalamus

-sexual receptivity from men

What neurotransmitter motivates sexual behavior? which inhibits it?

excitatory: dopamine

inhibites: serotonin

what sexual effect does dopamine have in males?

motivates sexual behavior and produces erection

How do SSRIs impact sexual receptivity?

increased serotonin inhibits sexual behavior

What does sexual dimorphism mean?

distinct difference between sexes

What are physical sexual dimorphisms in the brain?

Women: larger corpus callosum (cognitive skills), more grey matter in thinking (dorsolateral prefrontal cortex) and talking (superior temporal gyrus).

Men: larger right hemisphere, larger overall, less symmetrical

What 2 areas of the brain are larger in women? (areas that control talking and "think before acting")

dorsolateral prefrontal cortex: think before act

superior temporal gyrus: talking

What are the 2 most common hypotheses that suggest how homosexuality can develop?

Social influence: home environment or "early seduction"

Biological: gender nonconformity early in childhood. (commonly accepted)

What % of americans are LGBT?

4.5%

What does SDN-POA stand for?

Sexually dimorphic nucleus of the preoptic area

In lab rat tests, what occured when females were injected with testosterone before birth?

devleoped a male sized SDN-POA

-injection correlates with spike in testosterone that regular male rats have before birth

-early testosterone impacts sexual orientation

How does testosterone levels compare between adult gay/straight men

similar levels during adulthood

-indicates differences will be prenatal

How does increased prenatal testosterone impact brain development?

testosterone increases cerebral symmetry (straight male/lesbian female trait)

What genetic factors can influence sexual orientation?

-siblings of gay/lesbian more likely to be homosexual

-more older brothers -> more likely to be gay

The suprachiasmatic nucleus (SCN) is [larger/smaller] in gay men compared to straight.

larger

-will also contain more vasopressin secreting cells

The anterior commisure (AC) is (larger/smaller) in gay men compared to straight?

larger

-also larger in women

What behavior/skills are associated with higher levels of estrogen?

enhanced speech/manual skills

decreased spatial ability and aggression

Enhanced multitasking abilities in women can be attributed to what sexually dimorphic development?

larger corpus callosum

-better connection between hemispheres

Enhanced spacial abilities in men can be attributed to what sexually dimorphic development?

larger right hemisphere

-also better at single task compared to multitasking

-better connection from "front to back" of brain

How does the body maintain homeostasis?

negative feedback

-redundancy to ensure homeostasis

compensatory action is started by a deviation from the ______?

set point

What part of the brain controls thermal physiological homeostatic responses?

preoptic area (POA)

-behavior like sweating, dilation, breathing that are not controllable

what part of the brain controls thermal behavioral homeostatic responses?

lateral hypothalamus

-shivering, moving to warmer area

A lesion in the preoptic area (POA) would impair what type of response?

physiological response to temperature change

high solute concentration results in what type of thirst?

osmotic thirst

Hypovolemic thirst is stimulated by?

loss of fluid volume

What do baroreceptors detect?

detects loss in volume of fluids

- does not detect change in concentration

-can be intra or extracellular

what happens when baroreceptors detect low fluid volume?

-arteries constrict to raise blood pressure (vasopressin)

-thirst and salt craving

Hypovolemia induces the release of what 2 hormones?

renin: secreted by kidney in response to lower blood volume, initiates cascade to form angiotensin II

vasopressin: released in response to angiotensin II, constricts arteries and reduces blood flow to bladder

What is the angiotensin cascade?

-angiotensinogen gets converted by renin to make angiotensin I

-angiotensin I gets converted by ACE to make angiotensin II

-angiotensin II gets converted by aminopeptidase to make angiotensin III

What does angiotensin II do?

-blood vessel constriction

-vasopressin/aldosterone release

what area of the thalamus does angiotensin II act on?

subfornical organ

-subfornical organ activates POA to initiate drinking

what effect do semipermeable membranes have on high salt concentration?

water can move in and out of cells. salt stays outside of cells. water moves to where more salt is, causing cells to shrink

osmosensory neurons act in response to what homeostatic disturbance?

rise in blood osmotic pressure (high solute concentration)

-stimulus is only extracellular due to semipermeable membrane

where are osmosensory neurons located?

anterior hypothalamus (OVLT)

-organum vasulosum of lamina terminalus

what happens when osmosensory neurons respond to high solute concentration?

-vasopressin/ADH released by posterior pituitary

-opens mechanical gated Na+ channels

What is the difference between glucose and glycogen?

glucose: principle fuel (readily usable by brain)

glycogen: short term storage of glucose in liver (used by body)

what is the process of converting glucose to glycogen called and what enzyme does it use?

glycogenesis, insulin

Where is insulin stored?

beta cells of pancreas

What external factors can regulate food intake?

emotions

lifestyle

environmental cues

food characteristics

What cells produce leptin?

adipose/fat cells

high insulin and glucose levels would [increase/decrease] appetite.

decrease

-sympathetic nervous system activates

-energy levels go up; go do stuff

What would result from defective leptin production in adipose tissue?

body recieves incorrect information about satiety

-leads to overeating

-can be caused by insensitive receptors

What occurs during low levels of leptin?

lower body temp, energy and reproductive function

-parasympathetic nervous system activates

-preserve energy; go eat