Thermoregulation What is temperature?

Thermoregulation What is temperature?

Measure of the mean kinetic energy Intrinsic property- independent of object characteristics size, mass etc

Liquid/Gas Solid

Heat capacity or thermal mass?

Measure of the ability of a substance to store heat kJ g-1

Extrinsic property = varies with characteristics of object Size, mass, volume etc

Thermoregulation

Death Valley Pup Fish Death Valley

Trematomous- Antarctic notothaenid Antarctica

Life Exists Within a Narrow Range

Uniqueness of Water Hydrogen Bonds

Freezes at 0 °C

Evaporates at 100 °C O

H H O H H

Heat of vaporization = 540 cal/ml or 40.65 kJ/mol

Heat of fusion = 79.82 cal/g or 333.55 kJ/g

Heat content = 1 cal/g or cp = 75.3 J K−1 mol−1

O H H O

H H … … …

Heat of vaporization of H2O, is more than five times the energy required to

heat the same quantity of water from 0 °C to 100 °C

Common Compunds

Amm

onia

Buta

ne

Etha

nol

Hydr

ogen

Met

hane

Met

hano

l

Prop

ane

Phsp

hine

Wat

er

Hea

t of v

apor

izat

ion

kJ k

g-1

0

500

1000

1500

2000

2500

Heat of Evaporation

Amm

onia

Buta

ne

Etha

nol

Hydr

ogen

Met

hane

Met

hano

l

Prop

ane

Phos

phin

e

Wat

er

Hea

t of f

usio

n (m

eltin

g) (c

al g

-1)

0

20

40

60

80

100

Melting Point

Etha

nol

Met

hane

Met

hano

lPr

opan

e

Wat

erEt

hane

Glyc

erol

Form

ic a

cid

Acet

ic a

cid

Acet

one

Benz

ene

Myr

istic

aci

dPa

lmiti

c ac

idSt

earic

aci

dPa

raffi

n w

ax

Hea

t of F

usio

n (c

al g

-1)

0

20

40

60

80

100

The heat of fusion can also be used to predict solubility for solids in liquids. Provided an ideal solution is obtained the mole fraction (x2) of solute at saturation is a function of the heat of fusion, the melting point of the solid (Tfus) and the temperature (T) of the solution:

Thus the higher the heat of fusion the higher the solubility! Water has very high heat of fusion = high solubility

Thus Water is an Excellent Solvent!!

Water as a Solvent

Pressure

Not an issue for organisms that live at or near sea level

How Much of the Available Habitat is at Sea Level?

Dumbo Squid

Angler Fish Giant Deep Water Isopod

The world's deepest fish (Abyssobrotula galatheae) was found in the Puerto Rican Trench at a depth of 8,372

meters

160 180 200 220 240 260 280 300 320

Day (julian)

1000

800

600

400

200

Dep

th (m

)Elephant Seal Foraging Trip

Blainville’s Beaked Whale

11 meters

Hooker et al PRS 2012

Considerable Variation in Foraging Depths

Gibbs Free Energy

ΔG = ΔH – TΔS + PΔV

Where: ΔG = free energy of reaction ΔH = change in enthalpy ΔS = change in entropy T = temperature P = pressure

Temperature Effects Q10

Temperature

Potential for Biochemical Adaptation is Limited

Somero et al 1996

Temperature Adaptation

Membrane Fluidity

Varies with

Temperature and Pressure

Heat Shock Protein aka Stress Proteins

• HSPs (Heat Shock Proteins) – Molecular Chaperones – Stabilize unfolded state of proteins – Assist in refolding of tertiary state

• Highly conserved across Kingdoms – Animals

• Large proteins dominate • HSP60, HSP70, HSP90, HSP100, Lon

– Plants • HSP10 HSP27, ubiquitin

Changing temperature induces a cytoplasmic factor, HSF, which then changes from an inactive monomer to an active trimeric form, HSF*. This regulates the promoter region of the heat shock protein (HSP) gene, initiating the production of HSP mRNAs. Existing ribosome complexes are disrupted by the thermal shock, RNAs bound to them are released or degraded, and the new mRNA is preferentially translated, the HSPs are then distributed to the most sensitive nuclear and cytoplasmic sites. There is also a feedback interaction between some HSPs and HSF.

Regulation of Heat Shock Proteins

How Do Animals Avoid Freezing?

Conform vs Regulate

Body mass

Met

abol

ic ra

te

29 X

8X

slope = 0.75

unicellular

ectotherms

endotherms

Temperature

Met

abol

ic ra

te

endotherm

ectotherm

8 x 10 times

Behavioral Temperature Regulation

Behavioral Thermoregulation

Met

abol

ic ra

te

Time

Endotherm

Ectotherm

8 - 10X

50-100 X

winter

Hi Tb day

Low Tb night

summer

Tongue

Heat flow

Gray Whale Tongue (a cool meal)

Arteries transport blood to tongue

Veins return blood to body

Why doesn’t the dolphin testes “fry”? Cool temperatures important

for spermatogenesis

Why doesn’t the dolphin testes “fry”? Cool temperatures important

for spermatogenesis

Cool blood from fins cool the testes

Why doesn’t the dolphin testes “fry”? Cool temperatures important

for spermatogenesis

Cool blood from fins cool the testes

Hot blood from testes goes to the fins