Chapter 11

24

The role of the detector in a regulatory mechanism is to

monitor the value of the system variable.

recognize stimuli that might change the value of the system variable.

establish the value of the set point in response to environmental conditions.

restore the system variable to the set point.

An essential feature of all regulatory mechanisms is

a satiety mechanism.

negative feedback.

continuous feedback.

a neural control mechanism.

Satiety mechanisms

monitor system variables.

replenish depleted stores of food, fluid, or nutrients.

are a second correctional mechanism if detectors fail to work properly.

monitor the activity of correctional mechanisms.

Approximately two-thirds of the body's water is contained in the _____ fluid.

intracellular

extracellular

intravascular

interstitial

If the fluid inside a cell is isotonic to the interstitial fluid

their volumes are equal.

water will not tend to move in or out.

water will diffuse out of the cells through osmosis.

osmotic pressure may cause the membrane to rupture.

The _____ of the interstitial fluid must be closely regulated, but its _____ usually remains within normal limits.

production; excretion

excretion; volume

tonicity; volume

volume; tonicity

If we drink more water than we need, _____ secretion of _____ causes the kidneys to excrete more _____.

decreased; vasopressin; water

deceased; aldosterone; water

increased; vasopressin; sodium

increased; aldosterone; sodium

Osmometric thirst occurs when the

tonicity of the interstitial fluid increases.

volume of the intravascular fluid decreases.

blood flow to the kidneys decreases.

blood level of renin increases.

The stimulus for osmometric thirst is

renin secretion

a decrease in urine production.

hypovolemia.

cell dehydration.

The easiest way to produce volumetric thirst in an experimental animal is to give an injection of

a colloid.

a saline solution.

saralasin.

losartan.

A behavioral effect of angiotensin II is

aversion to a high protein diet.

production of a salt appetite.

near cessation of drinking.

an absence of food-related drinking.

The detectors for volumetric thirst are located in the

posterior pituitary gland and the hypothalamus.

kidneys and the bladder.

kidneys, heart, and large blood vessels.

stomach and large intestine.

.The region around the anteroventral third ventricle of the brain including the OVLT

monitors evaporation rate through skin temperature receptors.

contains osmoreceptors that stimulate thirst and vasopressin secretion.

initiates hypovolemia.

is the weakest portion of the blood-brain barrier.

Angiotensin is _____ which _____ the blood brain barrier.

both a peptide and a hormone; does not cross

a peptide; crosses

both a hormone and a transmitter substance; crosses

an enzyme; does not cross

Angiotensin

blocks vasopressin secretion.

lowers blood pressure.

stimulates aldosterone secretion.

increases urine output.

The subfornical organ

does not appear to have any angiotensin receptors.

secretes saralasin which blocks angiotensin.

is the site of action of angiotensin.

breaks down angiotensin.

The effect of the subfornical organ on drinking occur through its _____ outputs

autonomic

behavioral

endocrine

metabolic

The angiotensin receptors in the median preoptic nucleus

are stimulated by angiotensin that crosses the blood-brain barrier.

detect angiotensin secreted as a transmitter substance by terminal buttons there.

are an example of the redundant systems that have evolved in the brain.

control the secretion of vasopressin

Lesions of the zona incerta

have no effect on the stimuli for volumetric thirst.

stimulate salt intake.

abolish drinking in response to injections of the colloid polyethylene glycol.

produce a profound deficit in osmometric drinking.

Where does aldosterone appear to exert its behavioral effects?

medial nucleus of the amygdala

lateral hypothalamus

zona incerta

median preoptic nucleus

Rats who received preloads of water in the mouth drank _____ than rats who received the preloads in the stomach.

more

less

the same amount of water

the same amount of water, but more slowly

Research that used an esophageal fistula to prevent water from reaching the stomach suggest that satiety receptors in the mouth and throat

play a greater role that first believed.

have a short-lived effect.

cannot signal satiety if connections with stomach receptors are blocked.

and stomach are of equal importance.

When the pylorus of an experimental animal is constricted by a noose stomach contents

back up into the esophagus and throat

fall to the ground.

continue to diffuse into the blood through the capillaries.

cannot leave the stomach.

Atrial natriuretic peptide stimulates the

excretion of sodium.

secretion of renin.

retention of water.

elevation of blood volume.

Feeding questions

dbaccbdacdacdbcbabbcdcca

The short-term fuel reservoir is located in __________ and is filled with __________.

adipose tissue; triglycerides

digestive tract; amino acids

pancreas; glucose

the cells of the liver and muscles; glycogen

During the fasting phase of metabolism

supplies of glucose are abundant.

most cells live on fatty acids.

glycerol and fatty acids are converted into triglycerides.

excess nutrients are stored in the liver, muscles, and adipose tissue.

During the absorptive phase of metabolism

the blood level of glucose rises.

the pancreas ceases to secrete insulin.

proteins, carbohydrates, and fats are used to fuel the cells of the body.

glucose dissolves in fats and is stored in adipose tissue.

As recorded in their diaries, subjects ate the most food when

the food was familiar.

the food had a sweet taste.

other people were present.

they were alone.

Omnivores

are limited by the distribution of their food.

are completely dependent on one type of food.

do not obtain all essential nutrients from one type of food.

eat only meat.

Conditioned flavor aversions

confer an evolutionary advantage on some species and do not occur by chance.

permit omnivores to avoid foods that are dangerous.

can interfere with mechanisms that regulate total body weight.

are short-lived.

Lipoprivation can be induced by injections of

insulin.

2-DG.

capsaicin.

methyl palmoxirate (MP).

Detectors in the liver that signal lipoprivic hunger appear to be sensitive to

changes in their own internal rate of metabolism.

blood level of particular nutrients.

availability of insulin.

the amount of lipids stored in adipose tissue.

Using a pyloric cuff, researchers demonstrated that the

volume of stomach contents is more important than its nutritive content for satiety.

stomach contains receptors that prevent overeating.

stomach contains receptors that monitor the nutritive value of its contents.

stomach communicated information about satiety through the vagus nerve.

Injections of cholecystokinin (CCK)

activate stretch receptors in the stomach.

promote stomach emptying.

stimulate a carbohydrate appetite.

suppress eating.

By injecting glucose and fructose into the hepatic portal vein, researchers confirmed that the liver

contains receptors that respond when the liver receives nutrients from the intestines.

metabolizes sugars.

is the first organ to signal satiety.

breaks down fatty acids.

If ob mice are given an injection of leptin

they lose weight rapidly because they develop diabetes and cannot metabolize glucose.

they eat even greater quantities of food.

their weight returns to normal.

eating behavior is not affected.

Lesions of the area postrema and nucleus of the solitary tract (AP/NST)

stimulate a carbohydrate appetite.

reduce the ability to distinguish between flavors.

stimulate fos production.

abolish both glucoprivic and lipoprivic feeding.

Lesions of the __________ produce __________ and lesions of the __________ abolish __________.

lateral hypothalamus; hunger; ventromedial hypothalamus; satiety

ventromedial hypothalamus; overeating; lateral hypothalamus; eating.

paraventricular nucleus; overeating; ventromedial hypothalamus; undereating

ventromedial hypothalamus; satiety; paraventricular nucleus; obesity

Neuropeptide Y , which is secreted by neurons in the _____, _____.

area postrema; controls hormones that regulate the fasting phase of metabolism.

paraventricular nucleus; causes a rapid decline in blood glucose levels.

arcuate nucleus; stimulates ravenous eating.

ventromedial hypothalamus; abolishes eating.

Norepinephrine __________ carbohydrate intake and serotonin __________ it.

abolishes; stimulates

increases; decreases

stimulates; increases

decreases; increases

Leptin is _____

secreted by well-fed adipose tissue and inhibits eating.

a by-product of protein metabolism and inhibits the release of neuropeptide Y.

secreted by the liver during the fasting phase of metabolism and decreases metabolic rate.

secreted by neurons in the brain and does not cross the blood-brain barrier.

Which one of these conditions appears to contribute least to overeating and obesity?

social customs concerning food

unhappiness and depression

hereditary differences

an efficient metabolism

People with an efficient metabolism

must eat more food to maintain their body weight.

have difficulty loosing weight even on a reduced calorie diet.

have difficulty matching food intake to physical activity.

do not have any calories left over for deposit in long-term nutrient reservoirs.

The agouti mouse has a mutation of the gene responsible for the production of _____ receptors.

neuropeptide Y (NPY)

leptin

melanocortin-4

galanin

Gastroplasty, a surgical procedure to help obese people loose weight, results in

feelings of satiety when a small amount of food is eaten.

nausea when too much food is eaten.

increased secretion of CCK

nimiety when a small amount of food is eaten.

Fenfluramine, a drug that helps obese people loose weight, stimulates the release of

neuropeptide Y.

insulin.

serotonin.

norepinephrine.

Anorexics

are unresponsive to the effects of food.

do not experience hunger.

have an intense fear of becoming obese.

attempt to reduce their need for calories by reducing physical activity.

The cerebrospinal fluid of anorexics contains elevated levels of

neuropeptide Y.

cholecystokinin (CCK).

fenfluramine.

galanin.