Topic 13: Energetics & Performance · _____ (cutaneous respiration) All amphibians Especially...

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Topic 13: Energetics & Performance

� How are gas exchange, circulation & metabolism inter-related?

� Gas Exchange� How is it done in air and water?

� What organs are involved in each case?

� How does ventilation differ among taxa?

� Circulation� What are the main components of circulation?

� How does circulation work?

� How does the anatomy of the heart differ among taxa?

� Metabolism� What are the different types of metabolic rates?

� What are the two types of metabolism?

� How is performance influenced by temperature?

How are gas exchange, circulation &

metabolism inter-related?

Mammalian circulation – ignore the detailsMammalian circulation – ignore the details

© McGraw-Hill

� What are the components of the gas exchange system?

� What are the components of the circulatory system?

� How are gas exchange, circulation & metabolism interrelated?

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How are gas exchange, circulation &

metabolism inter-related?

Mammalian circulation – ignore the detailsMammalian circulation – ignore the details

© McGraw-Hill

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Gas Exchange

� Two main purposes

� ______________ from environment to tissues

� ________________ from tissues

� Gas exchange occurs in both air and water

� “Reptiles” generally exchange gases in air

� Amphibians do this in both air and water

© R Tramontano, PJB

Ambystoma tigrinum

Gas Exchange

� Two types of structures for respiration

� ________________

� Lungs

� ________________

� Gills, skin, pharynx, cloaca

� Amphibians have many non-pulmonary gas exchange structures (also often lungs)

� Reptile have predominantly pulmonary gas exchange

Gas Exchange

� Non-pulmonary: Amphibians

� Gas exchange and water balance are related through same structures

� Gas exchange structures:

� ______________ – plethodontids

� ________ (cutaneous respiration)

� All amphibians

� Especially hellbender, hairy frog

� _____________

� All larval amphibians

� Paedomorphic adults

Stebbins & Cohen 1995, Fig. 3.5; EJ Routman

Gas Exchange

� Non-pulmonary: “Reptiles”

� Not prevalent because of keratinized skin

� Hydrophiinae (sea snakes)

� _____________________

� Some Testudines

� Rheodytes leukops, an Australian Pleurodire

� Has ________________ lined with villi

� Pump water in and out of bursae ~80 times/minute

http://www.divegallery.com/sea_krait.htm

Pough et al 2004, Fig 4-35

Gas Exchange

� Pulmonary – using lungs

� Widespread (obviously)

� Requires _______________ of the lungs� Exhalation of O2 poor, CO2 rich air

� Inhalation of O2 rich, CO2 poor air

� Most amphibians use _________________________

Liem et al. Fig. 18-14

Gas Exchange

� Pulmonary ventilation

� Lepidosaurs use _________________

� Expansion of thoracic cavity creates negative pressure �Inhalation

� In lizards, air moves between lungs during locomotion

� In snakes, pressure changes

� In _______________ lung where gas exchange occurs

� Not much in __________ part, where air is stored

Pough et al 2004, Fig 7-5, 7-6

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� Pulmonary ventilation

� Testudines have a rigid shell

� mm. transversus abdominis & pectoralis control size of

visceral cavity, facilitating ventilation

� Crocodylia use the liver

� m. diaphragmaticus pulls liver anteriorly

� This compresses lungs, leading to exhalation

Gas Exchange

Pough et al 2004, Fig 7-7

Circulation

� Components of the circulatory system� Heart

� Vessels (veins, arteries, capillaries)

� Blood

� The heart pumps the blood through the vessels to:� Lungs/gills

� Organs

� Muscles

� Transports _____________ & ___________ Mammalian circulation – ignore the details

© McGraw-Hill

Circulation

� Circulation pattern depends on gas exchange structure

� Gills (larval amphibians)

� ________________

� Heart � ___________ �___________ � Heart

� O2-poor blood goes to gills

� O2-rich blood goes to body

� Same as fishes

www.universe-review.ca

Circulation

� Lungs (most others)

� ___________________

� Heart � ___________ �Heart � ________ � Heart

� Pulmonary circuit has lower blood pressure than systemic circuit

� Variation in how heart is divided among taxa

www.universe-review.ca

Circulation

� _______________ arteries

� Paired vessels in adult amphibians

� Divide into:

� Pulmonary arteries

� Cutaneous arteries

� Skin is part of pulmonary circuit, provides:

� 20-90% O2 uptake

� 30-100% CO2 release

� What amphibians would

have almost all gas exchange through skin?

Photo © EJ Routman

Circulation

� Variation in heart morphology: Anura� 3 chambers

� _____________

� _____________

� Oxygenated and deoxygenated blood mix in heart!

� ______________ and channels formed by trabeculae help keep O2

rich and poor blood separate

� “Good enough” for slower metabolism

Pough et al 2004, Fig 7-8

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Circulation

� Variation in heart morphology: Testudines & Squamata

� 3 chambers (2 atria, 1 ventricle)

� Ventricle subdivided into 3 chambers:

Pough et al 2004, Fig 7-9

• _______________

• _______________

• _______________

• Atrioventricular valve blocks interventricular

canal between CA & CV

• Muscular ridge

divides CV & CP

O2 rich

O2 poor

Circulation

Pough et al 2004, Fig 7-10

O2 rich

O2 poor

� Variation in heart morphology: Crocodylia

� 4 chambered heart:

� _______________

� _______________

� Separation of pulmonary and systemic circuits

� _______________________ acts as a shunt

� Allows the movement of blood between circuits

Circulation

� What are shunts for?

� ______________________� Controlling [O2] affects pH� Can supply more oxygen to

tissues when animal is not breathing

� ______________________� Controlling amount of blood

in the systemic circuit affects heating and cooling rates

� ______________________� R�L shunt� Blood bypasses the lungs

during diving, etc.

Proceedings of the Royal Society

Metabolism

� The use of sugars to produce energy

� This energy is used for:� _______________

� Movement

� _______________

� Reproduction

� Anything else the animal does

� Sugars are transported to cells by _______________

� Sugars are metabolized in ____________

Photos © PJB, B Rourke

Metabolism

� Metabolic rate� Varies with activity

� ___________ metabolic rate

� Minimum energy consumption to stay alive

� Postabsorptive, inactive, inactive part of day

� ___________ metabolic rate

� Postabsorptive, inactive, but alert

� ___________ metabolic rate

� Maximal aerobic rate

� At cusp of switching to anaerobic metabolism

� Maximal O2 intake

Pough et al. 2004, Fig 7-11

Metabolism

� Maximum metabolic rate occurs at maximum aerobic speed (MAS)

� During sustainable activity� _______________________

_______________________

� Glucose is metabolized

� Water and CO2 are produced

� During unsustainable activity� _______________________

� Glycogen is metabolized

� Lactate is produced, leading to fatigue

Pough et al. 2004, Fig 7-11

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Metabolism

� All metabolism produces ATP, which is used as energy

� _____________________ is aerobic� 1 sugar � 35 ATP + CO2 +H2O

� Efficient, but slow

� Good for sustained activity

� _____________________ is anaerobic� 1 sugar � 3 ATP + Lactic Acid

� Inefficient but fast

� Good for short term, high output activity

www.palaeos.com

Metabolism

� Sceloporus jarrovii use glycolytic metabolism during territorial defense

� Routine activity� _____________

� Little ________ build up

� Territorial defense� Intense

� Includes running and biting other males

� ___________________

� [Lactate] proportional to# bites/minute

PJB; Pough et al. 2004 Fig 7-13

Metabolism

� Temperature affects performance in ectotherms

� Affects locomotion in Phelsuma dubia

� At high temps, they take ________________

� Stride duration is affected by how fast

muscles can __________________________

� Stride length is ________________________

Bergmann & Irschick 2006; Photo © PJB

10 15 20 25 30 35 40

Temperature (C)

-1.0

-0.5

0.0

0.5

Log m

ax velocity (m/s) a bab

Velocity

10 15 20 25 30 35 40

Temperature (C)

0

10

20

30

40

50

60

70

80

St ride Length (mm)

a ab b b

10 15 20 25 30 35 40

Temperature (C)

0.0

0.1

0.2

0.3

Stride Duration (s)

a dab bc cd

Stride Duration Stride Length

Metabolism

� Post-meal metabolism in snakes

� Digestion uses a lot of energy, especially when meal is big

� Some pythons consume ~10X more oxygen at peak digestion

Ott & Secor 2007

• Also, intestine of a fed snake:

• More blood

• More mucous

• Thicker intestinal lining

Time

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Metabolism

� Calling in frogs is also energetically expensive

� The higher the calling rate, the higher the metabolic rate

� Some call 1500X/hour

� V02 increases 10X

??; Pough et al. 2004, Fig 7-18

Metabolism

� Calling in frogs is energetically expensive…

� …but is it worth it?

Pough et al. 2004, Fig 7-19, 7-20