Biopsyc test 3

homeostasis

tendency to maintain a variable such as temperature, within a fixed range

set point

a value that the body works to maintain

negative feedback

homeostatic processes that reduce discrepancies from the set point

allostasis

the adaptive way in which the body changes its set point depending on the situation

how does allostasis differ from homeostasis?

Homeostasis keeps certain body variables within a fixed range by reacting to changes. Allostasis acts in advance to prevent or minimize changes

basal metabolism

energy used to maintain a constant body temperature while at rest

ectothermic (poikilothermic)

controlling temperature by relying on external sources of heat or cooling

endothermic (homeothermic)

controlling temperature by the body’s physiological mechanisms

What is the primary advantage of maintaining a constant high body temperature?

A constant high body temperature keeps an animal ready for rapid, prolonged muscle activity even in cold weather.

Why did mammals evolve a temperature of 37°C (98°F) instead of some other temperature?

Animals gain an advantage in being as warm as possible and therefore as fast as possible. However, proteins lose stability at still higher temperatures.

preoptic anterior hypothalamus (POA)

controls the autonomic responses such as shivering, sweating, changes in heart rate and metabolism, and changes in blood flow to the skin

What are the sources of input to the POA/AH?

receives input from temperatures in the skin and organs, and many cells sense their own temperature.

If you had damage to your POA/AH, what would happen to your body temperature?

you would be much less able to shiver, sweat, or control other physiological mechanisms that control body temperature. However, you could still try to find a place in the environment that keeps you close to your normal temperature.

What evidence indicates that fever is an adaptation to fight illness?

During a fever, the body will shiver or sweat to maintain its elevated temperature at a nearly constant level. a moderate fever inhibits bacterial growth and increases the probability of surviving a bacterial infection.

What is the primary advantage of maintaining a constant high body temperature?

It keeps the muscles ready for rapid, prolonged activity even in cold weather.

Cells in the POA/AH regulate body temperature by monitoring what?

Skin temperature and the temperature of the POA/AH itself

vasopressin

hormone released by the posterior pituitary that raises blood pressure by constricting blood vessels

antidiuretic hormone (ADH)

enables the kidneys to reabsorb water from urine; also known as vasopressin

Osmotic thirst

caused by eating salty foods. Triggered by certain neurons that detect the loss of their own water

hypovolemic thirst

caused by the loss of fluid by bleeding or sweating

osmotic pressure

tendency of water to flow across a semipremeable membrane from the area of low solute concetration to the area of high solute concentration

subfornical organ (SFO)

brain structure adjoining the third ventricle of the brain, where its cells monitor osmotic pressure and sodium concertation

lateral preoptic area

part of the hypothalamus that controls drinking

supraoptic nucleus

part of the hypothalamus that controls the release rate of vasopressin

paraventricular nucleus (PVN)

part of the hypothalamus in which activity tends to limit meal size and damage leads to excessively large meals

Why are you likely to feel thirst just before bedtime? Would you feel just as thirsty if you went to sleep at an unusual time?

your body secretes vasopressin, which helps conserve water and also stimulates thirst. Both responses help you get through the night while you cannot drink. Your circadian rhythm triggers the increased vasopressin, so you would not feel as thirsty before sleep at an unusual time.

angiotensin II

hormone that constricts the blood vessels compensating for the drop in blood pressure; triggers thirst

aldosterone

adrenal hormone that causes the body to retain salt

hypovolemic thirst

caused by low blood volume and relived by water containing solutes.

which of these happens after you eat something salty?

water flows out of the cells

what would happen as a result of adding salt to the body’s extracellular fluids?

Increased osmotic thirst

what does aldosterone do?

it helps the kidneys and other glands retain salt

sham-feeding

procedure in which everything that an animal swallows leaks out a tube connected to the esophagus or stomach

what evidence showed that taste is not sufficient for satiety?

animals that sham-feed do not become satiated, regardless of how much they taste

vagus nerve

tenth cranial nerve, which has branches to and from stomach and serval other organs

duodenum

part of the small intestine adjoining the stomach; first digestive site that absorbs nutrients

cholecystokinin (CCK)

hormone that is released by the distension of the duodenum

what evidence shows that stomach distention is sufficient for satiety

If a cuff is attached to the junction between the stomach and duodenum so that food cannot leave the stomach, an animal becomes satiated when the stomach is full

what are two mechanisms by which CCK increases satiety?

When the duodenum is distended, it releases CCK, which closes the sphincter muscle between the stomach and duodenum, increasing the rate at which the stomach distends. Also, neural signals from the intestines cause cells in the hypothalamus to release a shorter version of CCK as a neuromodulator.

insulin

pancreatic hormone that enables glucose to enter the cells

glucagon

pancreatic hormone that stimulates the liver to convert stored glycogen to glucose

type 1 diabetes

impaired glucose absorption caused by low levels of insulin secretion

why do people with very low insulin levels eat so much ?

those with very low levels, (type 1 diabetes) cannot get glucose to enter their cells and therefore, they are constantly hungry

why do people with constantly high levels eat so much?

deposit much of their glucose into fat and glycogen, so within a short time after a meal, the supply of blood glucose drops

leptin

Hormone released by fat cells in proportion to their volume

arcuate nucleus

hypothalamic area with sets of neurons for hunger and satiety

ghrelin

chemical released by the stomach during a period of food deprivation; also released as a neurotransmitter in the brain, where it stimulates eating

name three hormones that increase satiety

Insulin, CCK, and leptin

What hormone that increases hunger

ghrelin

How does the inhibitory transmission from the hunger cells lead to increased eating?

the output inhibits the paraventricular nucleus, and thereby stops it from inhibiting the later hypothalamus

what is the role of melanocortin

excite neurons in the paraventricular nucleus, and therefore decrease appetite

lateral hypothalamus

area of the hypothalamus that controls insulin secretion, alters taste responsiveness, and facilitates feeding in other ways

How does eating more carbohydrates increase tryptophan in the brain?

Increased insulin removes phenylalanine from circulation.

What causes Type 2 diabetes?

Cells become insensitive to the effects of insulin.

How do the “hunger” cells of the arcuate nucleus increase eating?

By inhibiting the paraventricular nucleus

Which part of the body secretes ghrelin?

The stomach

The drug that is most effective for weight control binds to receptors for what chemical?

1. The correct answer

   Glucagon-like protein 1

Temperature regulation is a likely explanation for which aspect of anorexia nervosa?

Increased exercise

sexual selection

tendency for a gene to spread in the population if it makes individual smore appealing to the opposite sex

what evolutionary advantage suggested for why men tend to be more jealous of a woman’s sexual infidelity

For a man to spread his genes, he should be certain that the children he supports are his own. If the woman to whom he is bonded mates with another man, she threatens that certainty.

according to the published data, what do turner syndrome, Klinefelter syndrome, and XXY conditions have in common?

The Turner syndrome and Klinefelter syndrome correlate with decreased fertility. The Klinefelter syndrome and the XYY conditions correlate with an increased probability of impaired learning or cognition.

Mullerian ducts

precursors to female internal structures

wolffian ducts

precursors to male internal structures

SRY gene

sex-determining region on the Y chromosome, causes undifferentiated gonads to develop into testes

testes

sperm-producing organs

androgens

testes-produced hormones that are more abundant in males

ovaries

the female’s egg-producing organs

estrogens

family of hormones that are more abundant in females

steroid hormones

androgens and estrogens are steroid hormones, they contain four carbon rings

testosterone

an androgen chemical

estradiol

a hormone in the estrogen family

progesterone

steroid hormone that prepares the uterus for the implantation of a fertilized ovum and promotes the maintenance of pregnancy

organizing effects

long-lasting effects of a hormone that are present during a sensitive period early in development

activating effects

temporary, continuing only while a hormone is present

What would be the external genital appearance of a mammal exposed to high levels of both androgens and estrogens during early development?

A mammal exposed to high levels of both male and female hormones will appear male.

What would be the external genital appearance of a mammal exposed to a low level of both androgens and estrogens in early development?

A mammal exposed to low levels of both will appear female. External genital development depends on the presence or absence of androgens.

Why is any individual’s brain more masculinized or feminized in some areas than others?

The mechanisms for sexual differentiation vary from one brain area to another. People vary in the genetics and epigenetics that modify brain

what evidence links children’s toy play to prenatal hormones?

girls whose mothers had higher testosterone levels during pregnancy tend to play with boys’ toys more than the average for other girls

impotence

the inability to have an erection

by what mechanism does testosterone affect the hypothalamic areas responsible for sexual behavior

testosterone primes hypothalamic cells to be ready to release dopamine

menstrual cycle

a periodic variation in hormones and fertility over the course of about 28 days

follicle-stimulating hormone (FHS)

chemical released from the anterior pituitary; promotes the growth of a follicle in the ovary

luteinizing hormone

hormone released from the anterior pituitary that causes the follicle to release an ovum

at what time in a woman’s menstrual cycle do her estradiol levels increase? When are they the lowest?

Estradiol levels increase during the days leading up to the middle of the menstrual cycle. They are lowest during and just after menstruation.

when is a woman most likely to act sexy and initiate sexual activity

during the periovulatory period

What factors are responsible for maternal behavior shortly after rats give birth? What factors become more important in later days?

The early stage of rats’ maternal behavior depends on a surge in the release of prolactin and estradiol. A few days later, experience with the young maintains maternal behavior after the hormone levels begin to drop.

gender identity

the gender that a person considers himself or herself to be

congenital adrenal hyperplasia (CAH)

the overdevelopment of the adrenal glands from birth

androgen insensitivity (testicular feminization)

condition in which individuals with an XY chromosome pattern have the genital appearance of a female

if a genetic female is exposed to extra testosterone during prenatal development, what behavioral effect is likely?

most likely than most other girls to prefer boy-typical activities

what would cause a genetic male (XY) to develop a partly feminized external anatomy?

prevents testosterone from binding to its receptors will develop an appearance that partly or completely resembles a female

what caused some people’s genitals to appear female at birth, but develop the male pattern of adolescence

male mutation that prevented conversion of testosterone to dihydrotestosterone, which is more effective at masculinizing the genitals

congenital adrenal hypertrophy results from disrupted feedback between which two structures?

the hypothalamus and the pituitary

studies on genetic males who fail to produce 5α-reductase 2 support what conclusion

prenatal hormones influence gender identity and sexual orientation

In what way was INAH-3 distinctive for most of the gay men, in comparison to heterosexual men, in LeVay’s study and the follow-up research?

This nucleus had neurons with smaller than average volume.

cells in the POA/AH regulate body temperature by monitoring what? 

skin temperature and temperature of POA/AH itself

would adding salt to the body’s extracellular fluids increase or decrease osmotic thirst?

Increase because it draws water from the cells into the extracellular spaces

During osmotic thirst, neurons in the OVLT and subfornical organs detect changes in osmotic pressure and send information to hypothalamic areas responsible for vasopressin secretion and for drinking

true

What best distinguishes a homeotherm from a poikilotherm?

Homeotherms use internal mechanisms to maintain constant temperature

What role do the stomach’s mechanoreceptors play in knowing when to stop eating?

Stomach distension hits the vagus nerve, which signals to the hypothalamus to decrease appetite