10.1 Temperature Regulation

Question 0

Similarly, homeostatic processes in animals trigger psychological and behavioural activities that keep certain variables with in a set range. In many cases, the range is so narrow that we refer to it as a ___ ____, a single value that the body works to maintain.

Answer 0

set point

Question 1

Psychologist Walter B. Cannon (1929) introduced the term ____ to refer to temperature regulation and other biological processes they keep the body variables within a fixed range.

Answer 1

homoeostasis

Question 2

Mechanisms maintain ____ blood levels of water, oxygen, glucose, sodium chloride, protein, fat, and acidity.

Answer 2

constant

Question 3

Processes that reduce discrepancies from the set point are known as ____ ____.

Answer 3

negative feedback

Question 4

Much of ____ ____ can be described as negative feedback: something causes a disturbance, and behaviour proceeds until it relieves the disturbance.

Answer 4

motivated behaviour

Question 5

The body’s setpoints change from time to time. To describe these dynamic changes, researchers use the term ____, which means the adaptive way in which the body changes its set points depending on the situation. Much of that control depends on cell in the hypothalamus.

Answer 5

allostasis

Question 6

If you were to list your strongest motivations of life, you might not think to include ____ ____, but it has a high priority biologically.

Answer 6

temperature regulation

Question 7

An average young adult expends about 2600 _____ (kcal) per day. Where do you suppose all that energy goes?

Answer 7

kilocalories

Question 8

Most of our energy goes to ____ ____, the energy used to maintain a constant body temperature while at rest. Maintaining your body temperature requires about twice as much energy as do all other activities combined.

Answer 8

basal metabolism

Question 9

Amphibians, reptiles, and most fish are ____. That is, their body temperature matches the temperature of their environment.

Answer 9

poikilothermic

Question 10

Poikilothermic animals lack physiological mechanisms of temperature regulation, such as shivering and sweating. The informal term is ____, but that term is misleading because poikilothermic animals remain warm most of the day by choosing an appropriate location.

Answer 10

cold-blooded

Question 11

Mammals and birds are ____, except that certain species become poikilothermic during hibernation. Homeothermic animals use physiological mechanisms to maintain a nearly constant body temperature despite changes in the temperature of the environment.

Answer 11

homeothermic

Question 12

Homeothermy is costly, especially for small animals. An animal generates heat in proportion to its total ____, but it radiates heat in proportion to its ____ ____.

Answer 12

Mass : surface area

Question 13

To cool ourselves when the air is warmer than body temperature, we have only one physiological mechanism – _____. Humans sweat to expose water for evaporation.

Answer 13

evaporation

Question 14

As water evaporates, it ____ the body. However, if the air is humid as well as hot, the moisture does not evaporate.

Answer 14

cools

Question 15

Furthermore, you endanger your health if you cannot drink enough to replace the water you lose by sweating. If you sweat without drinking, you start becoming ____. You then protect your body water by decreasing your sweat, despite the risk of overheating.

Answer 15

dehydrated

Question 16

Several physiological mechanisms increase your body heat in a cold environment. One is ____. Any muscle contractions, such as those of shivering, generate heat.

Answer 16

shivering

Question 17

A second mechanism is ____ ____ to the skin prevents the blood from cooling too much.

Answer 17

decreased bloodflow

Question 18

A third mechanism works well for most mammals, though not humans: when cold, they fluff out their fur to increase ____.

Answer 18

insulation

Question 19

We also use ____ mechanisms, just as poikilothermic animals do. In fact, we prefer to rely behaviour when we can. The more we regulate our temperature behaviourally, the less energy we need to spend physiologically.

Answer 19

behavioural

Question 20

We ___ a great deal to support our high metabolism so that even when the weather is cold, we can still run as fast and as far as we need to.

Answer 20

eat

Question 21

If warmer is better, why not heat ourselves to an even ____ ____? First, maintaining a high temperature requires more fuel and energy. Second, and more importantly, beyond about 40° or 41°C, proteins begin to break their bonds and lose their useful properties.

Answer 21

higher temperature

Question 22

Our body temperature of 37°C is a trade-off between the advantages of high temperature for ____ ____ and the disadvantages of high temperature for ____ ____.

Answer 22

rapid movement : protein stability

Question 23

Birds lay eggs and sit on them, instead of developing them internally, because the birds ____ ____ is too hot for an embryo.

Answer 23

internal temperature

Question 24

The physiological changes that defend body temperature – such as shivering, sweating, and changes in bloodflow to the skin – depend on areas in and near the hypothalamus, mainly the ____ ____ and the preoptic area, which is just anterior to the anterior hypothalamus.

Answer 24

anterior hypothalamus

Question 25

Because of the close relationship between the preoptic area and anterior hypothalamus, researchers often treat them as a single area, the ____ ____/____ ____, or POA/AH.

Answer 25

preoptic area/anterior hypothalamus

Question 26

The POA/AH and a couple of other hypothalamic areas send output to the hindbrain’s ____ ____, which controls the physiological mechanisms.

Answer 26

raphe nucleus

Question 27

The POA/AH monitors body temperature partly by monitoring its own ____.

Answer 27

temperature

Question 28

That is, the animal acts as if it feels hot when it’s ____ is hot, and acts as if it feels cold when it’s ____ is cold.

Answer 28

hypothalamus

Question 29

Cells of the POA/AH also receive input from temperature receptors in the ____ and the ____. The animal shivers most vigourously when both the POA/AH and the other receptors are cold. It sweats or pants vigorously when both are hot.

Answer 29

skin and spinal-cord

Question 30

Seperate populations of cells within the POA/AH and a couple other hypothalamic areas regulate different aspects of temperature regulation, such as _________.

Answer 30

shivering and changes in blood flow

Question 31

After damage to all of the POA/AH, mammals can still regulate body temperature but only by the same ____ ____ that a lizard might use, such as seeking a warmer or cooler location.

Answer 31

behavioural mechanisms

Question 32

Bacterial and viral infections generally cause ____, an increase in body temperature.

Answer 32

fever

Question 33

The fever is not part of the illness; it is part of the body’s ____ against the illness.

Answer 33

defence

Question 34

When bacteria, viruses, fungi, or other intruders invade the body, they metabolise ____ (white blood cells) to attack them.

Answer 34

leucocytes

Question 35

The leucocytes release small proteins called ____ that attack the intruders.

Answer 35

cytokines

Question 36

Cytokines also stimulate the ____ ____, which sends signals to the hypothalamus, increasing the release of chemicals called ____.

Answer 36

vagus nerve : prostaglandin

Question 37

____ of a particular kind of prostaglandin receptor in one nucleus of the hypothalamus is necessary for fever.

Answer 37

Stimulation

Question 38

A fever represents ____ ___ ____ for body temperature. Just as you shiver or sweet when your body temperature goes below or above its normal 37°C, when you have a fever of say 39°C, you shiver and sweet whenever your body temperature deviates from that level.

Answer 38

increased set point

Question 39

Certain types of ____ grow less vigorously at high temperatures than at normal mammalian body temperature.

Answer 39

bacteria

Question 40

Fever enhances activity of the ____ ____. Developing a moderate fever probably increases an individual’s chance of surviving a bacterial infection.

Answer 40

immune system

Question 41

However, a fever above about 39°C in humans does more harm than good, as a fever above 41°C is _____.

Answer 41

life-threatening