9. Internal Regulation Flashcards
What does negative feedback do?
a. It establishes a set point.
b. It changes the set point.
c. It eliminates the set point.
d. It reduces discrepancies from a set point.
d. It reduces discrepancies from a set point.
How do poikilothermic (ectothermic) animals regulate their body temperature, if at all?
a. They move to a location with a more favorable temperature.
b. They use physiological mechanisms such as shivering and sweating.
c. They increase their metabolic rate.
d. They do not regulate their body temperature at all.
a. They move to a location with a more favorable temperature.
What is the primary advantage of maintaining a constant high body temperature?
a. It saves us the energy from having to look for a comfortable temperature.
b. It enables us to survive in warmer climates.
c. It keeps the muscles ready for rapid, prolonged activity even in cold weather.
d. Other things being equal, animals with a higher body temperature live longer than those with a lower temperature.
c. It keeps the muscles ready for rapid, prolonged activity even in cold weather.
If we inserted a probe into the POA/AH and directly heated that area, what if anything would happen?
a. The animal would shiver.
b. The animal would sweat or pant.
c. The animal would not react physiologically, but it would seek a cooler location.
d. The animal would not react in any way that affects body temperature.
b. The animal would sweat or pant.
When you have an infection, what causes the fever?
a. The infective agent directly stimulates the heart to beat faster.
b. The infective agent directly stimulates the muscles to shiver.
c. The immune system increases delivery of prostaglandins and histamine to the POA/AH.
d. The immune system decreases blood flow to the brain.
c. The immune system increases delivery of prostaglandins and histamine to the POA/AH.
Which of the following is the most correct description of a fever?
a. Fever is one way by which the body fights against bacteria.
b. Fever is one way in which bacteria cause damage to the body.
c. Fever is an indication that the POA/AH is not functioning properly.
d. Fever occurs only in homeothermic animals.
a. Fever is one way by which the body fights against bacteria.
If you lacked vasopressin, how would your drinking change, if at all?
a. Your drinking would not change.
b. You would drink less.
c. You would drink more.
c. You would drink more.
What would happen as a result of adding salt to the body’s extracellular fluids?
a. Increased osmotic thirst
b. Decreased osmotic thirst
c. Increased hypovolemic thirst
d. Decreased hypovolemic thirst
a. Increased osmotic thirst
How does hypovolemic thirst differ from osmotic thirst?
a. Hypovolemic thirst is stronger.
b. Osmotic thirst is stronger.
c. Someone with hypovolemic thirst prefers slightly salty water.
d. Someone with hypovolemic thirst prefers pure water.
c. Someone with hypovolemic thirst prefers slightly salty water.
People differ in their likelihood of consuming milk products in adulthood because of what type of genetic difference?
a. Genetic variants in taste buds
b. Genetic variants in neurotransmitters of the hypothalamus
c. Genetic variants in ability to metabolize lactose
d. Genetic variants in mechanisms of hypovolemic thirst
c. Genetic variants in ability to metabolize lactose
Which of the following describes the relationship between taste and eating?
a. Taste is sufficient to control eating.
b. Taste is necessary for eating.
c. Taste is both necessary and sufficient for eating.
d. Taste is neither necessary nor sufficient for eating, although it contributes
d. Taste is neither necessary nor sufficient for eating, although it contributes
After surgical removal of someone’s stomach, what mechanism if any can produce satiety?
a. Distension of the duodenum
b. Entry of nutrients into the muscles and organs
c. None. The person stops eating altogether.
d. None. The person starts eating constantly.
a. Distension of the duodenum
When food distends the duodenum, the duodenum releases the hormone CCK. By what peripheral (non-CNS) mechanism does it increase satiety?
a. CCK increases stomach contractions.
b. CCK tightens the sphincter muscle between the stomach and the duodenum.
c. CCK increases the ability of nutrients to enter cells.
d. Cells in the hypothalamus release CCK as a neurotransmitter.
b. CCK tightens the sphincter muscle between the stomach and the duodenum.
Increased blood glucose causes increased release of ___, which ___ the ability of glucose to enter the cells.
a. insulin . . . increases
b. insulin . . . decreases
c. glucagon . . . increases
d. glucagon . . . decreases
a. insulin . . . increases
People with untreated type 1 diabetes have ___ levels of insulin, ___ levels of blood glucose, and ___ levels of hunger.
a. high . . . high . . . high
b. low . . . high. . . . high
c. low . . . low . . . high
d. low . . . low . . . low
e. low . . . high . . . low
b. low . . . high. . . . high
Leptin is produced by the ___ cells. In most cases it tends to ___ appetite.
a. fat . . . decrease
b. hypothalamic . . . decrease
c. pancreas . . . increase
d. intestinal . . . increase
a. fat . . . decrease
Which is the only neuropeptide that increases hunger?
a. Ghrelin
b. Melanocortin
c. Leptin
d. Insulin
a. Ghrelin
How do taste and ghrelin promote eating and arousal?
a. They increase excitation from the paraventricular nucleus to the arcuate nucleus, an area that excites the lateral hypothalamus.
b. They increase inhibition from the paraventricular nucleus to the arcuate nucleus, an area that inhibits the lateral hypothalamus.
c. They increase excitation from the arcuate nucleus to the paraventricular nucleus, an area that excites the lateral hypothalamus.
d. They increase inhibition from the arcuate nucleus to the paraventricular nucleus, an area that inhibits the lateral hypothalamus.
d. They increase inhibition from the arcuate nucleus to the paraventricular nucleus, an area that inhibits the lateral hypothalamus.
.If researchers could find a safe drug that stimulates melanocortin receptors, what would be the probable benefit?
a. Improving memory
b. Helping people go to sleep
c. Combatting anorexia nervosa
d. Helping people lose weight
d. Helping people lose weight
The lateral hypothalamus facilitates feeding in several ways. Which of the following is not one of them?
a. It alters taste sensations.
b. It enhances responses to food in the cerebral cortex.
c. It increases insulin secretion.
d. It decreases digestive secretions.
d. It decreases digestive secretions.
Damage to the ventromedial hypothalamus produces a steady increase in the release of insulin. Which of the following is a consequence?
a. The animal decreases its appetite for carbohydrates.
b. More of each meal is stored as fat.
c. The animal eats fewer, but larger meals.
d. Body temperature increases.
b. More of each meal is stored as fat.
What evidence suggests that high ghrelin levels lead to weight gain in Prader-Willi syndrome?
a. People with this syndrome continue to have high ghrelin levels regardless of whether they gain or lose weight.
b. A mutated gene for melanocortin causes nearly 5 percent of cases of severe obesity.
c. Ghrelin stimulates hunger-related neurons in the arcuate nucleus.
d. People with Prader-Willi syndrome have other problems in addition to weight gain.
a. People with this syndrome continue to have high ghrelin levels regardless of whether they gain or lose weight.
How has the prevalence of obesity changed since the availability of high-fructose corn syrup and artificially sweetened diet beverages?
a. Each of them helped lower the prevalence of obesity.
b. High-fructose corn syrup helped lower obesity rates, but diet drinks did not.
c. Diet drinks helped lower obesity rates, but high-fructose corn syrup did not.
d. The prevalence of obesity has increased after the availability of both of these.
d.The prevalence of obesity has increased after the availability of both of these.
People with bulimia have elevated ghrelin levels. Is this abnormality a likely cause of bulimia? And what is the evidence?
a. No. It is probably not a cause. The abnormality is common in the ethnic groups who are most likely to develop bulimia.
b. No. It is probably not a cause. As people recover from bulimia, their ghrelin level returns toward normal.
c. Yes. It is probably a cause. People who show high ghrelin early in life are likely to develop bulimia later.
d. Yes. It is probably a cause. Inducing high ghrelin in rats causes the rats to develop bulimia.
b.No. It is probably not a cause. As people recover from bulimia, their ghrelin level returns toward normal.
How does the idea of allostasis differ from homeostasis?
Homeostasis is a set of processes that keep certain body variables within a fixed range. Allostasis is an adjustment of that range, increasing it or decreasing it as circumstances change.
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 temperatures much above 37°C (98°F).
What are the sources of input to the POA/AH?
The POA/AH receives input from temperatures in the skin, the organs, and the brain including cells in the POA/AH itself. It also receives prostaglandins and histamines when the immune system detects an infection.
How can an animal regulate body temperature after damage to the POA/AH?
It can regulate temperature through behavior, such as by finding a warmer or cooler place.
What evidence indicates that fever is an adaptation to fight illness?
The body will shiver or sweat to maintain its elevated temperature at a nearly constant level. Also, fish, reptiles, and immature mammals with infections use behavioral means to raise their temperature to a feverish level. Furthermore, a moderate fever inhibits bacterial growth and increases the probability of surviving a bacterial infection.
If you lacked vasopressin, would you drink like a beaver or like a gerbil? Why?
If you lacked vasopressin, you would have to drink more like a beaver. You would excrete much fluid, so you would need to drink an equal amount to replace it.
Would adding salt to the body’s extracellular fluids increase or decrease osmotic thirst?
Adding salt to the extracellular fluids would increase osmotic thirst because it would draw water from the cells into the extracellular spaces.
Who would drink more pure water—someone with osmotic thirst or someone with hypovolemic thirst?
Someone with osmotic thirst would drink more water. Someone with hypovolemic thirst would drink more of a solution containing salts.
What genetic difference is most important for variants in likelihood of drinking milk in adulthood?
Likelihood of drinking milk in adulthood depends largely on a gene that controls the ability to digest lactose, the main sugar in milk.
What evidence indicates that taste is not sufficient for satiety?
It is not sufficient, because animals that sham-feed chew and taste their food but do not become satiated.
What evidence shows that stomach distension 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. CCK therefore increases the rate at which the stomach distends. Also, neural signals from the intestines cause certain cells in the hypothalamus to release CCK as a neurotransmitter, and at its receptors, it triggers decreased feeding
Why do people with very low insulin levels eat so much? Why do people with constantly high levels eat so much?
Those with very low levels, as in type 1 diabetes, cannot get glucose to enter their cells, and therefore, they are constantly hungry. They pass much of their nutrition in the urine and feces. Those with constantly high levels deposit much of their glucose into fat and glycogen, so within a short time after a meal, the supply of blood glucose drops.
What would happen to someone’s appetite if insulin levels and glucagon levels were both high?
When glucagon levels rise, stored glycogen is converted to glucose, which enters the blood. If insulin levels are high also, the glucose entering the blood is free to enter all the cells. So the result would be decreased appetite
.Name three hormones that increase satiety and one that increases hunger.
Insulin, CCK, and leptin increase satiety. Ghrelin increases hunger.
Which neuropeptide from the arcuate nucleus to the paraventricular nucleus is most important for satiety?
Melanocortin
In what ways does the lateral hypothalamus facilitate feeding?
Activity of the lateral hypothalamus improves taste, enhances cortical responses to food, and increases secretions of insulin and digestive juices.
In what way does eating increase after damage in and around the ventromedial hypothalamus? After damage to the paraventricular nucleus?
Animals with damage to the ventromedial hypothalamus eat more frequent meals. Animals with damage to the paraventricular nucleus of the hypothalamus eat larger meals.
Why did the Pima begin gaining weight in the mid-1900s?
They shifted from a diet of local plants that were seasonally available to a calorie-rich diet that is available throughout the year.
In one study, rats eating the less-caloric yogurt gained more weight than those eating the more-caloric type. What explanation was proposed?
The rats unlearned their usual calibration that more sweets mean more energy and therefore stopped compensating after eating other sweets.
What evidence from rats suggests that bulimia resembles an addiction?
Rats that alternate between food deprivation and a very sweet diet gradually eat more and more, and they react to deprivation of the sweet diet with head shaking and teeth chattering, like the symptoms of morphine withdrawal.
Biologically, what is the necessary condition for life?
A coordinated set of chemical reactions.
Our behavior is organized to:
keep the right chemicals
in the right proportions and
at the right temperature.
homeostasis (HO-mee-oh-STAY-sis)
refers to temperature regulation and other biological processes that keep body variables within a fixed range
set point
a single value that the body works to maintain.
negative feedback
Processes that reduce discrepancies from the set point are known as negative feedback.
Allostasis
(from the Greek roots meaning “variable” and “standing”), which means the adaptive way in which the body anticipates needs depending on the situation, avoiding errors rather than just correcting them
basal metabolism
the energy used to maintain a constant body temperature while at rest.
poikilothermic = ectothermic
That is, their body temperature matches the temperature of their environment. A synonym is ectothermic, meaning dependent on external sources for body heat.
homeothermic - Endothermic
A synonym is endothermic, meaning capable of generating body heat internally. Homeothermic animals use physiological mechanisms to maintain a nearly constant core temperature despite changes in the temperature of the environment.
shivering, sweating, and changes in blood flow to the skin depend on which part/s of the Brain
hypothalamus - especially the anterior hypothalamus and the preoptic area,
How physiological mechanisms such as shivering, sweating, changes in heart rate and metabolism, and changes in blood flow to the skin are controlled? and by which part?
The POA/AH and a couple other hypothalamic areas send output to the hindbrain’s raphe nucleus,
Which chemicals cause shivering, increased metabolism and Fever
prostaglandins and histamines
POA/AH received inputs from which receptors??
- Temp. receptors of skin
- Temp. receptors in the brain and internal organs
- Infection triggers immune response & release prostaglandins and histamines
Which Brain area releases the hormone vasopressin
posterior pituitary
Function of vasopressin
raises blood pressure by constricting blood vessels. Vasopressin is also known as antidiuretic hormone (ADH) because it enables the kidneys to reabsorb water from urine and therefore make the urine more concentrated.
two types of thirst?
- Eating salty foods causes osmotic thirst, and
2. losing fluid by bleeding or sweating induces hypovolemic thirst.
Osmotic pressure
the tendency of water to flow across a semipermeable membrane from the area of low solute concentration to the area of higher concentration.
How does the brain detect osmotic pressure?
1 Receptors around the third ventricle,
- OVLT (organum vasculosum laminae terminalis) and
- The subfornical organ (SFO)
- The OVLT also receives input from receptors in the digestive tract, enabling it to anticipate an osmotic need before the rest of the body experiences it
What areas of brain control the rate at which the posterior pituitary releases vasopressin?
supraoptic nucleus and the paraventricular nucleus (PVN),
Which part of Hypothalamus controls drinking ??
lateral preoptic area and surrounding parts of the hypothalamus,
sodium-specific hunger
An animal that becomes deficient in sodium shows an immediate strong preference for salty tastes, known as sodium-specific hunger . Neurons in several brain areas suddenly react much more strongly than usual to salty tastes
aldosterone (al-DOSS-ter-one),
a hormone that causes the kidneys, salivary glands, and sweat glands to retain salt
enzyme lactase required for?
metabolizing lactose, the sugar in milk.
sham-feeding experiment
sham-feeding experiments, everything an animal swallows leaks out of a tube connected to the esophagus or stomach. Sham-feeding animals eat and swallow almost continually without becoming satiated
Function of vagus nerve (cranial nerve X)
conveys information about the stretching of the stomach walls, providing a major basis for satiety.
Function of splanchnic (SPLANK-nik) nerves
convey information about the nutrient contents of the stomach
duodenum (DYOU-oh-DEE-num or dyuh-ODD-ehn-uhm)
the part of the small intestine adjoining the stomach. It is the first digestive site that absorbs a significant amount of nutrients.
Fat in the duodenum releases a hormone called?
OEA
Function of CCK Hormone
CCK constricts the sphincter muscle between the stomach and the duodenum, causing the stomach to hold its contents and fill more quickly than usual . Also it sends message to Hypothalamus to end the meal
insulin
Pancreatic hormone which enables glucose to enter the cells, except for brain cells, where glucose does not need insulin to enter.
glycogen
Some of the excess glucose produced by a meal enters the liver, which converts it to glycogen and stores it.
glucagon
Pancreatic hormone which converts Glycogen to Glucose again
Explain Function of arcuate nucleus
has one set of neurons sensitive to hunger signals and a second set sensitive to satiety signals. Damage to one set or the other can lead to starvation or excessive eating
Why cigarette smoking decreases appetite, and quitting smoking increases appetite, leading to weight gain.
Nicotine also stimulates the satiety neurons in the arcuate nucleus
Damage to Preoptic area Leads to?
Deficit in physiological mechanisms of temperature regulation
Damage to Lateral preoptic area Leads to?
Deficit in osmotic thirst due partly to damage to cells and partly to interruption of passing axons
Damage to Lateral hypothalamus area Leads to?
Undereating, weight loss, low insulin level (because of damage to cell bodies); underarousal, underresponsiveness (because of damage to passing axons)
damage to Ventromedial hypothalamus leads to ?
Increased meal frequency, weight gain, high insulin level
Damage to Paraventricular nucleus
Increased meal size, especially increased carbohydrate intake during the first meal of the active period of the day
