Download - Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair [email protected]
![Page 2: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/2.jpg)
What happens in the thermoneutral zone?
Ambient temperature
Meta
bolic R
ate
Thermoneutral Zone
Tb
![Page 3: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/3.jpg)
Endothermy & HomeothermyEndotherms generate their own
heatHomeotherms regulate their
body temperature by physiological or behavioural means
![Page 4: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/4.jpg)
EndothermyHeat productionHeat retentionRegulation
![Page 5: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/5.jpg)
Producing Heat I: All biochemical processes produce heat
Fig. 6.4
![Page 6: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/6.jpg)
Producing Heat II: Shivering ThermogenesisUncoordinated
muscular contractions
Performs no locomotor function
Uses ATP, therefore generates heat
![Page 7: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/7.jpg)
Producing Heat III: Non-shivering ThermogenesisFinding other ways to do
biochemical ‘work’ and to produce heat
![Page 8: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/8.jpg)
Acclimation to 6°C
Initially, rats shivered uncontrollably…
After acclimation, they maintained their body temperature without shivering
![Page 9: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/9.jpg)
Brown adipose tissue Highly vascularized
tissue with lots of mitochondria
Abundant in newborn mammals, declines with age
Can increase with acclimation/ acclimatisation (rats)
![Page 10: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/10.jpg)
Localisation of Brown Adipose Tissue
Fig. 9.29
![Page 11: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/11.jpg)
Generating heat through futile cyclesCircular biochemical reactions
that use up ATP and produce heat without achieving anything else
Mechanisms not well-understood…
![Page 12: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/12.jpg)
Futile cycles Ion cycling across membraneBreakdown and building of
triglycerides
![Page 13: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/13.jpg)
Uncoupling protein (thermogenin, UCP1)
Box 7.1
![Page 14: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/14.jpg)
Uncoupling protein (thermogenin, UCP1)
Box 7.1
![Page 15: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/15.jpg)
Uncoupling protein (thermogenin, UCP1)When thermogenin is activated,
proton transport into the mitochondrion is uncoupled from ATP synthesis ATP is expended pumping protons
out again, generating heatThe numerous mitochondria in
BAT are essentially futile pumping engines
![Page 16: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/16.jpg)
But birds don’t have BAT?!A UCP2/3 homolog
has been found in hummingbird muscle Another tissue with
lots of mitochondria Dual use of muscles
because of weight restriction?
![Page 17: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/17.jpg)
Being an endotherm is expensive!!
Clarke, 2006 Funct. Ecol. 20: 405-412.
![Page 18: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/18.jpg)
Counter-current heat exchange
Fig 9.34
![Page 19: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/19.jpg)
Countercurrent heat exchange
HotCold
• Heat is lost to the outside world
• More heat is then necessary to increase temperature upon return to the body
• A NET LOSS OF HEAT ENERGY
No transfer of heat between outgoing and incoming vessels
![Page 20: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/20.jpg)
Countercurrent heat exchange
HotCold
Allow heat transfer between outgoing and incoming vessels
• Heat transfers to the incoming vessel
• Less heat is lost to the outside world
• Less energy is required to re-heat the incoming blood
![Page 21: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/21.jpg)
Counter-current heat exchange
Fig 9.33
![Page 22: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/22.jpg)
Regional heterothermy
Exposed body parts are often cooler than core temperature Heat & energy
conservation Testes and brains
are often also kept a little cooler
Fig. 9.30
![Page 23: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/23.jpg)
Why fish are ectothermsFishes can generate heat just
like anything else with metabolism, but they have problems keeping it
Surrounded by thermally-conductive water
![Page 24: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/24.jpg)
Fish gills act as a heat sink
Fig. 22.10c
Fish Gills
![Page 25: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/25.jpg)
Why Fish are EctothermsFish are ectotherms because the
high blood flow across their large gill surface means that they lose heat to the environment really quickly
Heat retention is a major issue
![Page 26: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/26.jpg)
Tuna temperature gradients in 19°C Water – Regional Endothermy
29 °C
31 °C
27 °C
23 °C
19 °C
23 °C
![Page 27: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/27.jpg)
Rete mirabileA recurring theme – especially in
(but not exclusive to) fish Swim bladder Heater organs Oxygen delivery to retina
Allows for VERY effective countercurrent exchange of heat (and other things)
![Page 28: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/28.jpg)
Red muscle in Tuna
Tuna Salmon
![Page 29: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/29.jpg)
Area of
Rete
Fig. 9.43
![Page 30: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/30.jpg)
Red muscle temperature is elevated above water temperature
Fig. 9.44
Thermal Mass
![Page 31: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/31.jpg)
Where does the heat come from?Heat comes from the normal
heat produced by contractile activity of the red muscles The only difference is that the heat
is retained
![Page 32: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/32.jpg)
Why?Good question!To allow long migration through
water of different temperatures?To allow better performance as a
predator chasing prey into colder water?
Improvements in power output of muscles?
![Page 33: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/33.jpg)
Brain heaters in billfish
![Page 34: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/34.jpg)
Heater organ in Billfish
Brain
Carotid Artery
Carotid Rete
Heater OrganEye
7.2°C8.5°C
4.8°C1.3°C
![Page 35: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/35.jpg)
Heater organ in BillfishDerived from an extra-ocular eye
muscleNo contractile ability left63% mitochondria (by volume)Another 30% is sarcoplasmic
reticulumHeat is produced by futile
cycling of Ca2+ pumping
![Page 36: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/36.jpg)
Large sharks are also regional endotherms
![Page 37: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/37.jpg)
Regional endothermy evolved in bony fishes on at least three separate occasions
Fig 9.45
![Page 38: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/38.jpg)
Brain heaters evolved in bony fishes on at least two separate occasions
Fig. 9.45
Superior rectus muscle developed into a brain heater
Lateral rectus muscle developed into a brain heater
![Page 39: Biology 2672a: Comparative Animal Physiology Endothermy Dr Brent Sinclair bsincla7@uwo.ca](https://reader036.vdocuments.us/reader036/viewer/2022062321/56649eec5503460f94bfe8ea/html5/thumbnails/39.jpg)
Reading for next week(s) Two Guest Lectures
Hibernation Migration (are examinable) Note: Lecture Quiz 2 material ends NEXT
Thursday Reading to be announced on OWL Reading for Tues Oct 7 & Thu Oct 9:
Circulation Pp 611-641