The Energetic Costs of Meeting Environmental Challenges

The rates of chemical reactions are highly __________ dependent.

temperature

the process in which an individual organism adjusts to a gradual change in its environment (such as a change in temperature, humidity, photoperiod, or pH), allowing it to maintain performance across a range of environmental conditions.

Acclimatization

Acclimatization occurs in a ______ period of time (days to weeks), and within the organism's lifetime.

short

Changes in the rate of an enzymatic reaction can be due to either a _________ in the enzyme or to some other factor in enzyme kinetics.

molecular change

Over the general temperature range within which an ectothermic animal is active, metabolic rates usually increase ______ times for every 10C increase in ambient temperatures.

2 or 3

Over the general temperature range within which an ectothermic animal is active, metabolic rates usually increase 2 or 3 times for every ____C increase in ambient temperatures.

10

An important exception to the effect of temperature on enzymatic reactions are those found in the cells making up portions of an organism’s _____________.

biological clock

True or False: biological clock cells remain stable over a wide range of temperatures.

True

A fundamental biophysical determinant of membrane fluidity is the balance between saturated and unsaturated ___________.

fatty acids

Regulating membrane fluidity is especially important in ___________ organisms that cannot regulate their own body temperatures.

ectothermic

The general trend is an increase in unsaturated fatty acids at ______ temperatures and an increase in saturated fatty acids at _______ temperatures.

lower, higher

This compositional adaptation of membrane lipids serves to maintain the correct membrane fluidity at the new conditions. What is it called?

homeoviscous

Another factor playing a role in homeoviscous membrane acclimatization to temperature changes is what?

cholesterol

What helps to stabilize the cell membrane in response to temperature changes?

Cholesterol

Ectotherms exposed to higher ambient temperatures will have ______ cholesterol in their cell membranes than members of the same species exposed to lower temperatures.

more

________ in cholesterol increases the stability of the membrane and adds rigidity to the membrane.

Increases

Endotherms tend to have ________ membrane cholesterol levels on average than do ectotherms.

higher

Organisms may also express specific proteins that may act as molecular chaperons and help the cell maintain function under periods of extreme stress. Called what?

Heat Shock Proteins

An animal’s body temperature depends on the amount of __________ contained per unit mass of body tissue.

heat (calories)

An animal’s body temperature depends on the amount of heat (calories) contained per unit mass of what?

body tissue

body heat = heat _______ + (heat gained - heat lost) = heat produced + heat transferred

produced

body heat = heat produced +__________ = heat produced + heat transferred

(heat gained - heat lost)

the temperature of an organism can be regulated by changes in the rate of __________ and heat transfer.

heat production

the temperature of an organism can be regulated by changes in the rate of heat production and _________.

heat transfer

Factor affecting rate of body heat: The activity of moving around will increase heat production by elevating metabolism.

Behavioral

Since muscular contractions generate heat, muscular activity will cause an _______ in body temperature.

increase

Factor affecting rate of body heat: The activation of certain ANS triggered hormones will cause an acceleration in the metabolization of adipose tissue causing an increase in body heat.

Hormonal

_________ mechanisms can also lead to an increase in basal temperature. These mechanisms are slower than are behavioral or hormonal responses.

Acclimatization

Acclimatization mechanisms can also lead to an increase in basal temperature. These mechanisms are _____ than are behavioral or hormonal responses.

slower

H_tot = H_v + H_c + H_r + H_e + H_s
H_tot = ?

total heat content

Htot = Hv + Hc + Hr + He + Hs
Hv = ?

heat produced metabolically

Htot = Hv + Hc + Hr + He + Hs
Hc = ?

heat lost or gained

Htot = Hv + Hc + Hr + He + Hs
Hr = ?

net heat transfer by radiation

Htot = Hv + Hc + Hr + He + Hs
He = ?

heat lost by evaporation

Htot = Hv + Hc + Hr + He + Hs
Hs = ?

stored body heat

the transfer of heat between objects in contact with each other.

Conduction

Conduction is the ______ transfer of kinetic energy of molecular motion from molecule to molecule, from higher temperatures to lower temperatures.

direct

The transfer of heat contained in a mass of gas or liquid by the movement of that mass.

Convection

Convection can be thought of as the diffusion of heat in a ________.

fluid

Convection is the concerted, collective movement of groups or aggregates of molecules within fluids (e.g., liquids, gases) through _______.

diffusion

the transfer of heat by electromagnetic radiation.

Radiation

Unlike convection and conduction, radiation does not require ________ between the two items exchanging heat.

contact

the conversion of a liquid to a gas with an input of heat energy.

Evaporation

An animal’s temperature reflects its ability to ______ heat.

store

Smaller animals have greater surface areas than do larger animals meaning that they exchange heat at a _______ rate.

greater

Some animals will alter their _______ relative to the sun to increase or decrease surface area to affect the exchange of heat with the environment.

position

The closer an animal’s body temperature is to the ambient temperature, the less will be the temperature gradient, and the _____ will be the rate of heat exchange.

lower

The ______ the difference in Temperature Gradient the ______ the rate of heat exchange from warm to cold.

greater, greater

Heat transfer can be altered by _________ adjustments.

internal physiological

What are animals that through thermoregulation maintain a stable internal body temperature regardless of external influence.

Homeotherms (aka; Homoiotherms)

Homeotherms typically maintain their body temperature within a very ______ range. by controlling both heat loss and heat production.

narrow

Typically, homeotherms are thought to be?

mammal and birds

What is an organism whose internal temperature varies considerably.

Poikilotherms

Many terrestrial and aquatic ectotherms are _________.

poikilothermic

_________ generate their own body heat through metabolism.

Endotherms

Typically, endotherms keep their internal temperature _________ the ambient temperature.

elevated above

Endotherms require a ______ investment of metabolic energy.

great

An endotherm will tend to have a metabolic rate at approximately ____ times that of a similar sized ectotherm.

five

Many endotherms will have insulating integumentary structures, such as hair and feathers, which will allow them to _______ heat.

conserve

It has been hypothesized that mammals and birds evolved warm-bloodedness as a defense against what?

fungal infections

________ fungi can survive the body temperatures of warm-blooded animals.

Very few

Some ectotherms live in environments in which temperatures are practically constant, as is typical of regions of the?

abyssal ocean

The terms endotherm, ectotherm, homeotherms, and poikilotherm represent extremes of what?

thermoregulation

What refers to animals that can switch between ectothermic (or poikilothermic) and endothermic (or homeothermic) strategies?

Heterothermy

__________ heterotherms are a broad category of animals whose body temperatures vary over time.

Temporal

Even in these deep hibernators, the long periods of Torpor is interrupted by bouts of endothermic metabolism, called what?

Arousals (typically lasting between 4–20 hours)

Most of the energy spent during hibernation is spent in _______ (70-80%), but their function remains unresolved.

arousals

________ heterotherms describes organisms that are able to maintain different temperature "zones" in different regions of the body.

Regional

Regional heterotherms usually occurs in the limbs, and is made possible through the use of counter-current heat exchangers, such as the ________ found in tuna and certain birds.

rete mirabile

Leatherback Sea Turtles use the __________ to gather, and retain heat generated by their muscular flippers.

heat exchangers

Ectotherms living under _____ temperatures will have enzymes working at a higher rate of activity at temperatures many degrees below the temperatures required for the maximal activity rate for homologous enzymes.

low

________ animals which survive ice formation in the tissues

freeze-tolerant

____________ animals which tolerate the low temperatures but not the crystallization of the body fluids.

freeze-avoiding

________ agents are substances that act as seed crystals, facilitating the formation of ice by providing a surface where water molecules can freeze.

Ice nucleating

As temperatures fall below freezing the _________ fluids will freeze before the intracellular fluids because they possess ice-nucleating agents

extracellular

Ice crystals will form within the extracellular fluids excluding solutes and concentrating them in the unfrozen fluids. The elevated extracellular solute concentration will draw water out of the intracellular fluid.This will cause an increase in the _________ of intracellular fluid lowering its freezing point.

solute concentration

________ lowers the freezing point of body fluids to as low as –17C.

Glycerol

What is the state where body fluids are cooled below the freezing temperature but do not freeze because ice crystals fail to form.

Supercooling

Supercooling is common in what?

ectotherms

The osmotic concentration of the body fluids of fish is ______ than the osmotic concentration of sea water.

lower

What is that temperature for a given species above which most individuals respond with unorganized locomotion, subjecting the animal to likely death?

Critical thermal maximum

______ ectotherms exposed to higher than tolerable conditions will enact behavioral actions to deal with the problem.

Active

Class of specialized proteins which will resist the effects of enzymatic degradation due to high temperatures.

Heat shock proteins

Ectotherms rely largely on _______ heat sources such as sunlight to achieve their optimal body temperature for various bodily activities.

external

physiological term for animals that exhibit characteristics of both poikilothermy and homeothermy.

Heterothermy

Heterothermy refers to animals that can _____ between ectothermic (or poikilothermic) and endothermic (or homeothermic) strategies.

switch

In the case of _________ that practice heterothermy, they have the advantage of being able to maintain a higher degree of activity under a greater range of conditions than would the traditional ectotherms without the energetic costs of endothermy.

ectotherms

BMR for a homeothermic endotherm will be 7-20 times _______ than the BMR for a similar sized ectotherm.

higher

BMR for a homeothermic endotherm will be _____ times higher than the BMR for a similar sized ectotherm.

7-20

What is essentially an endotherm's temperature tolerance range.

Thermal Neutral Zone (TNZ)

Within the thermal neutral zone the basal rate of heat production is in ________ with the rate of heat loss to the external environment.

equilibrium

The animal can show ________ where it changes its body shape or moves and exposes different areas to the sun/shade, and through radiation, convection and conduction, heat exchange occurs.

postural changes

What allow control of the flow of blood between the periphery and the core to control heat loss from the surface of the body.

Vasomotor responses

Vasodilation _____ heat loss.

promotes

Vasoconstriction ________ heat loss.

reduces