Physiology

7/21/2019 Physiology

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Physiology and Functional

MorphologySupplement Text with:

1) a closer look at Cardiovascular system

“respiratory potential dictates virtually all life historycharacteristics known to partition organisms into theirrespective ecological and evolutionary niches”(O’Connor and Claessens 2009)

reproductive biology, activity patterns, locomotion, body

size

2) Consideration of adaptations to withstand cold andheat



homeotherms

poikilotherms

Ta ( C)

10 20 30 40

10

20

30

40

Tb (C)

Homeotherms and

Poikilotherms

(body temp)

Environmental Temp



Homeotherms

• “warm-blooded” vertebrates- birds

mammals

• !aintain "onstant Tb

• #ndothermi" (metabolism is so$r"e

o% bod& heat)

• 'ormal Tb rane is 3-42 derees C



*dvantaes o% Homeotherm&

• Can live in a variet& o% habitats

• Can res+ond ra+idl& to

environmental stim$li

• (,maller animals rea"t more ra+idl&

sin"e their metaboli" rate is hiher)



To Be Endothermic Requires Rapid

and Efficient Delivery of Oxygen to

Fuel Metabolism

• In birds and mammals cardiovascular andrespiratory systems have evolved to meet

need for enhanced exchange, transport and

delivery of respiratory gasses (oxygen and

carbon dioxide)



Especially at High Elevation

(Scott 2011)



Respiration

• The avian lung has the greatest known

relative gas exchange surface area and

thinnest barrier to oxygen diffusion, and incombination with anatomical

specializations is the most efficient lung of

all air-breathing vertebrates at oxygenextraction (from Quick and Ruben 2009)



Separate nutrient and waste Streams



Air Sac System



How Breathing

Works

See Fig. 6-5 in text

Negative pressure draws air through, could

collapse

Positive pressure pushes air through, no collapse



Cross Current Exchange

(Scott 2011)



Birds Versus Mammals

(Scott 2011)



Bellows Move Air• Lungs don’t move

• No diaphragm

• Air sacs fill bodycavity

• Ribs as a bellows

• Unique thighsupports abdominalair sacs



Sternum moves down,

Ribs move forward during

Inspiration

(Claessens 2009)

Muscles to uncinate processes may enable breathing when sternum

cannot be depressed



How to Keep Abdominal air sac

from collapsing during inhalation?

• Modern birds have wide hips– Great pelvic cross sectional area– Egg passage AND

accommodate large air sacs• Synsacrum and integratedthigh with body wall providebony and muscular support tosuspend air sac and keep itfrom collapsing duringnegative pressure ofinhalation

Thigh mass closer to body center (angled up) supports air

sac and doesn’t move much during walking

knee

ankle



When did These Specializations

Evolve?

(Sereno et al. 2008)(Sereno et al. 2008)



When did These Specializations Evolve?

(Sereno et al. 2008)



Staying Warm

• Feathers:increase # 15-52%, (depending on species)– Down and semiplumes provides insulation

• Feathers-”fluffing”-traps air– Effects of oil blob= creates a thermal window

• Lay on Fat• Large Body size (SA to V)•

Vasoconstrict, shiver• Migrate (latitude, altitude)• Burrow, group up



Tree Creepers (European)

The huddled masses.

*d t ti % C ld C diti



*da+tations %or Cold Conditions

avoidin H&+othermia

•Hibernation (also has +h&sioloi"al behavioral as+e"ts to it) – *llow Tb to a++roa"h Ta

– .ew birds hibernate

– Partial hibernators h$mminbirds

(at niht)




avoidin H&+othermia•

,+e"ial Case 1 the Poorwill

– /is"overed b& #C aeer on /e" 2 14 in

the Ch$"kwalla !ts o% so$thern Cali%ornia

– /e+ression in a ro"k wall 2 %eet %rom ro$nd



Jaeger, 1949



From Jaeger, E.C. 1949: Condor 51:105-109




avoidin H&+othermia• ,+e"ial "ase 2 hih

latit$de +en$ins

• 5ives in botha6$ati" andterrestrial worlds




avoidin H&+othermia

• ,+e"ial "ase 2 +en$ins

• 7n water

•Chroni" +roblem o% heat loss•lare tem+erat$re radient-o%%set b&

thi"k la&er %eathers and thi"k bl$bber




avoidin H&+othermia

• 8n land breedin season birds ha$l o$t on

islands o%% *ntar"ti"a

• territorial de%ense9 heat +rod$"tion

• in water heat lost easil& not in air on land•breedin a"tivities %all o%% on"e T* rea"hes

• 4 derees .

•.li++ers (modi%ied wins)- a thermal window




avoidin H&+othermia:h& don;t the %eet o% d$"ks eese $lls et"

%ree<e to i"e=

*nswer a "o$nter-"$rrent me"hanism

(arteries and veins ne>t to ea"h other)



Countercurrent Mechanism



Avoiding Hyperthermia



*da+tations %or Hot Conditions

avoidin H&+erthermia?irds

•

Pre-ada+ted %or hot "limates-hih T?(4- . hiher than mammals)

• !ost birds are neither no"t$rnal nor%ossorial so m$st meet the environment

head-on




avoidin H&+erthermia,tr$"t$ral ada+tations

!i"roevol$tion o% bod& si<e

.eathers- same idea as h&+othermia

e>"e+t that &o$ want to red$"e air s+a"e

C858@A5iht vs /ark B :ind vs Calm

Thermal windows ?are +la"es on skin-

birdsA$lar +o$"h %eet les %a"e




avoidin H&+erthermia

Ph&sioloi"al ada+tations

• Cardiovas"$lar "hanes-dilate bloodvessels to send more blood to skin s$r%a"e

also in"reased "ardia" o$t+$t

• #va+orative "oolinA+rimar& wa&




avoidin H&+erthermiaPh&sioloi"al ada+tations

?irds

•no sweat lands

•eva+orate water over l$ns air sa"s

and $lar +o$"h (some)

•

a""om+lished b& +antin $lar%l$tterin



Evaporative CoolingProlonged exposure to high ambient temperatures

Hyperthermia

Hyperventilation

Evaporative cooling

Rapid exchange of air

through air sacs

Body temperature lowers

vasodilation

Increased cardiac output

More blood sent to:

Skin surfaceFeet, wings, gular area





• 7n"rease water

intake

• ,eek "ool +la"es-shadows

veetation to

red$"e heat ain

Ph&sioloi"al ada+tations





?ehavioral ada+tations

*"tivit& +atterns

• be"ome less a"tive

• be "re+$s"$lar

• be no"t$rnal

• be a"tive near water

.ossorial habits



Sooty tern



Additional References

• Claessens, L. P. A. M. 2009. The skeletal kinematics of lungventilation in three basal bird taxa (emu, tinamou, and guinea fowl).J. Experimental Zoology 311A:586-599.

• Quick, D. E. and J. A. Ruben. 2009. Cardio-ppulmonary anatomy in

theropod dinosaurs: implications from extant archosaurs. J.Morphology 270:1232-1246.• O’Connor, P. M. and L. P. A. M. Claessens. 2009. Respiratory

evolution in sauropsids: progress and new approaches. J.Experimental Zoology 311A:549-550.

• Sereno, P. C. et al. 2008. Evidence for avian intrathoracic air sacs in

a new predatory dinosaur from Argentina. PLOS one. 3(9). E3303.• Scott, G. R. 2011. Elevated performance: the unique physiology of

birds that fly at high altitudes. J. Exp. Biol. 214:2455-2462

Physiology

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