Energy Balance Part B and Thermal Physiology

Question 1

general challenges of harsh temperatures (cold or hot)

Answer 1

1) freezing damage to cell membranes 2) chilling/heating damage to membranes 3) reaction rates will flucuate 4) extreme heat can result in water loss.

Question 2

temperature is a measure of _____, which is:

Answer 2

temperature is a measure of heat, which is the kinetic energy of molecules.

Question 3

the higher the temp, the ___ the reaction rates.

Answer 3

the faster the reaction rates, UP TO A POINT. high temps tend to be more trouble than low.

Question 4

the ___ equation quantifies the effect of temperature on biochemical reaction rates. outine this reaction. What is the value for most biological reactions?

Answer 4

Arrhenius Van’t Hoff equation.

Q10= rate at temp/rate at temp-10degrees

Q10= (R2/R1)^(10/T2-T1)

Usually, most biological reactions have a value of 2 or 3, meaning when the temperature is raised by 10 degrees, the reaction will double or triple

Question 5

How does the arrhenius Vant Hoff equation apply to metabolic rate?

Answer 5

Q10= (Mr2-Mr1)^(10/T2-t1)

Question 6

How does the Q10 of a reaction or metabolic rate change at different temps?

Answer 6

Changes at high temps = effect on rate is large

changes at low temps= effect on rate is small.

Question 8

Temperature of something is dependent on the amount of ___ contained per unit mass

Answer 8

amount of HEAT. (kinetic energy measure)

Question 9

T/F: heat moves down thermal gradients

Answer 9

true. it radiates. it spreads to places with less kinetic energy

Question 10

3 methods of heat gain

Answer 10

1) infrared radiation
2) conduction
3) metabolism

Question 11

how can you gain heat from infrared radiation?

Answer 11

• obtained by solar or reflected energy. can also get it from atmospheric or radiant from surfaces( ex/ hot rock)

Question 12

How can an animal gain heat from conduction?

Answer 12

direct contact with surface that is heated. ex/ snake on a warm rock

Question 13

what is thermal conductivity?

Answer 13

how easily heat is con- ducted by the molecules of the substances. thermal conductivity of an object depends how well it can be used to “heat something up”

Question 14

4 methods of heat loss

Answer 14

1) radiation
2) conduction
3) convection
4) evaporation

Question 15

what is convection

Answer 15

Convection refers to the transfer of heat energy by cur rents of air or water (the medium).

warmer air is less dense than cool air, and thus the warm air will move up. and heat surfaces/ objects that are higher up.

Question 16

forceful movements in the external medium, known as ___ _____, can carry heat away from a body

Answer 16

CONVECTION CURRENTS

Question 17

forced vs free convection

Answer 17

In FREE convection, any fluid motion is caused by natural means such as the buoyancy effect, i.e. the rise of warmer fluid and fall the cooler fluid.

Whereas in forced convection, the fluid is forced to flow over a surface or in a tube by external means such as a pump or fan.

Question 18

2 methods that hoary bats conserve heat

Answer 18

1) mother hoary bats roost on south-east side of trees. Allows them to heat up in the MORNING (sun rises in the east) when they do not have much energy and aren’t moving (therefore metabolism isn’t heating them much bc theyre nocturnal)
2) Hoary bats select trees in cluttered forest with open “pie wedge” on the southeast side. Preventing wind exposure

hoary bats thus save 1.24 kj/day of energy, which is about equivalent to saving 4 moths.

Question 19

total body heat is the sum of: (3 factors), and is a balance between ___ ___ and ___

Answer 19

Total body heat = heat produced + heat gained from environment - heat lost.

It’s a balance between thermal conduction (how well the animal loses/gains heat by touching objects) vs insulation ( how well it can retain heat)

Question 20

Why is evaporative heat loss so important when the ambient temperature is higher than the body temperature?

Answer 20

when Ta>tb, the heat will flow into the organism because of its thermal gradient. the animal is thus overheating. it is important that evaporative mechanisms are in place because heat cannot be lost through conduction/convection anymore.

because everything favors an increase in entropy, water from the organism (liquid state) will be vaporized into a gaseous state, increasing entropy and cooling the animal as it leaves the skin surface.

Question 21

Homeotherms vs ploikotherms

Answer 21

poikilotherms (poikilos, “changeable”)— animals whose body temperatures vary with the environment. essentially an ectotherm

homeotherms—animals with narrowly varying body temperatures. essentially an endotherm

Question 22

the more modern terms ectotherm and endotherm are descriptors of body temperature regulation based on :

Answer 22

the source of body heat.

Question 23

heterothermic endotherm

Answer 23

animals that vary between self-regulating their body temperature, and allowing the surrounding environment to affect it. ex/ animals that can undergo torpor

Question 24

ploikotherms are ectotherms which:

Answer 24

live in a thermally VARIABLE environment, such as aquatic environments. water has a high heat conductivity

Question 25

what are regional heterotherms

Answer 25

endothermic animals that allow "parts" to go cold under extreme temperatures to preseve core heat (ex/ caribou, wolves)

Question 26

what are temporal heterotherms

Answer 26

endothermic animals that let the whole body go cold. ex/ hummingbirds, mice, little brown bats

Question 27

\_\_\_\_ are changes in animal's physiology due to new, **naturally occurring** environmental conditions

Answer 27

ACCLIMATIZATION. ex/ seasonal temp change

Question 28

what is the dehnel effect?

Answer 28

type of acclimatization seen in small-bodied northern mammals. Results in an actual REDUCTION in body size and WHOLE ANIMAL BMR during the winter time.

Question 29

What is acclimation? Adaptation?

Answer 29

acclimation are changes induced in the lab. ex/ manipuatlion of Ta and Tb in the lab. adaptations are adjustment over evolutionary time

Question 30

some ectotherms can compensate biochemically for changes in body temperatures to maintain a slight sort of internal temp. what is this called?

Answer 30

called **metabolic compensation:** acclimatization to temperature changes allows an animal to maintain a useful level activity. an animal’s **_metabolic reactions_** in cold temperatures are **increased to a level that is closer to that of warm- acclimated animals** even though their body temperatures are that of the environment’s.

Question 31

4 ways ectotherms can metabolically compensate for fluctuations in body temperature (and ambient temperatures)

Answer 31

1) enzyme concentrations 2) homeoviscous membrane adaptation (cholesterol levels) 3) pH regulation (to maintain binding affinty of certain compounds) 4) isoform regulation.

Question 32

explain metabolic compensation in alligators

Answer 32

This particular study ex-amined the activity levels of key enzymes in muscle tissue. Note that for **Lactate DeHydrogenase**, measured in the laboratory at 15, 22.5, and 30°C, the **winter-acclimated animals have considerably higher enzyme activities** at all measurement temperatures. This biochemical adjustment allows the cold-acclimated al- ligator to move better in the cold.

Question 33

RMR? TNZ? TMR?

Answer 33

RMR= resting metabolic rate TNZ= thermoneutral zone TMR= torpid metabolic rate

Question 34

Explain the BMR, RMR, TMR (TORPID MR) and TNZ in an endotherm. draw a graph. How can MR be measured in endotherms

Answer 34

metabolic rates can be measured via HEAT PRODUCTION. Torpid MR is generally lower than RMR and BMR because they are operating at a considerably lower temperature. RMR and BMR DECREASE and ambient temp INCREASES because the body does not ned to work as hard to maintain body temperature.

Question 35

Heat loss can be calculated in terms of Q=C(Tb-Ta). What is C?

Answer 35

C= conductance, which is in the INVERSE of insulation. It measures the ability of a material to TRANSFER heat through conduction. therefore a person with lots of insulation is a bad conductor.

Question 36

Recall that heatloss can be measured as Q= C(tb-ta) HOw can you maintain a constant temp against a changing gradient? (ex/ Tb is constant while Ta changes).

Answer 36

C must DECREASE as Ta DECREASES. A person must then increase insulation if Ta increases because C is inversely proportional to I. Heat **production** does not increase as Ta decreases and gradient increases, contant body temperature more due to the fact that there is increased insulation.

Question 37

Explain how blood flow changes act as a method of thermoregulation

Answer 37

In a cold environment, blood can be diverted through shunts (anastomoses) **deep under the skin to reduce heat loss.** If body heat needs to be released to the environment, or if external heat needs to be absorbed from a warm environment, vessels just under the skin surface can be opened.