Animal Form and Function

Ch 40

A single-celled animal living in water

Figure 40.3a

Organisms must exchange matter and energy with the environment.

Diffusion

(a) Single cell

Figure 40.3b

Mouth

Gastrovascularcavity

Diffusion

Diffusion

(b) Two cell layers

Multicellular organisms with a sac body plan

External environmentFood CO2 O2Mouth

Animalbody

Respiratorysystem

Circulatorysystem

Nutrients

Excretorysystem

Digestivesystem

Heart

BloodCells

Interstitialfluid

AnusUnabsorbedmatter (feces)

Metabolic wasteproducts (urine)

The lining of the small intestine, a diges-tive organ, is elaborated with fingerlikeprojections that expand the surface areafor nutrient absorption (cross-section, SEM).

A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).

Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).

0.5 cm

10 µm

50 µ

m

Figure 40.4

Energy intake is used for maintaining homeostasis• Energy is used for

maintenance and homeostasis first• Any excess energy can go

towards growth or reproduction

Figure 40.7

Organic moleculesin food

Digestion andabsorption

Nutrient moleculesin body cells

Cellularrespiration

Biosynthesis:growth,

storage, andreproduction Cellular

work

HeatEnergylost infeces

Energylost inurine

Heat

Heat

Externalenvironment

Animalbody

Heat

Carbonskeletons

ATP

Body Size and Metabolic EfficiencyEndotherms Ectotherm

Annu

al e

nerg

y ex

pend

iture

(kca

l/yr

) 800,000 Basalmetabolicrate

ReproductionTemperatureregulation costs

Growth

Activitycosts

60-kg female humanfrom temperate climate

Total annual energy expenditures (a)

340,000

4-kg male Adélie penguinfrom Antarctica (brooding)

4,000

0.025-kg female deer mousefrom temperateNorth America

8,000

4-kg female pythonfrom Australia

Ener

gy e

xpen

ditu

re p

er u

nit m

ass

(kca

l/kg

•day

)

438

Deer mouse

233

Adélie penguin

36.5

Human

5.5

Python

Energy expenditures per unit mass (kcal/kg•day)(b)Figure 40.10a, b

• Large animals require more energy overall, but have a lower energy expenditure per unit mass.• Why? Surface area to

volume ratio helps them conserve energy• Ectotherms use less

energy overall and per unit body mass • Why? Do not waste

energy heating body

A homeostatic control system has three functional components

• A receptor• Control center• An effector

Positive vs negative regulation: see pogil

Figure 40.11

ResponseNo heat

produced

Roomtemperature

decreases

Heaterturnedoff

Set point

Toohot

Setpoint

Control center:thermostat

Roomtemperature

increases

Heaterturnedon

Toocold

ResponseHeat

produced

Setpoint

Regulators and Conformers

• Regulators use physiological responses to maintain constant internal conditions• Conformers are able to tolerate a range of a particular environmental

condition • In this example the Crab can tolerate a range of salt concentrations in the

environment. Too low or too high leads to death

Maintaining Homeostasis

•Ectotherms• Include most invertebrates,

fishes, amphibians, and non-bird reptiles

•Endotherms• Include birds and mammals

Ectotherms and Endotherms an example of regulators vs. conformers

Figure 40.12

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)

Body

tem

pera

ture

(°C)

40

30

20

10

10 20 30 400

Homeostatic control mechanisms support common ancestry

Systems reach equilibrium and no further exchange takes place

Systems do not reach equilibrium and exchange takes place along the entire length. More of the exchanged substance is transferred than in the previous example

• Countercurrent Exchange systems help animals maintain higher core temperatures in the cold- see diagrams for explanation of how. • Countercurrent exchange systems are evolutionarily conserved-seen in

terrestrial and aquatic animals

Reproductive strategies reflect energy availability in the environment

• When is the most energy available• Which season is best to reproduce/

support young?

Type 1: relatively few young, more parental investment/ care, most survive past infancy and die after adulthood

Type 3: have many young, young are small in size, few survive infancy, once adult or mature stage is reached most survive.

Type 2: young are as likely to die as adults. Intermediate number of offspring and parental care.

Responses to the environment can be behavioral or physiological

• Behavioral responses: behaviors that maximize organisms chances of survival• Seasonal Migration• Nocturnal or crepuscular activity• Reptiles (thermo-conformers) “sunning” when cold and

seeking shade when hot

This kangaroo is licking its forearms to cool itself by evaporation

Responses to the environment can be behavioral or physiological

• Physiological Responses • Vasodilatation when hot, vasoconstriction when

cold• Insulation layer of body fat in marine mammals• Torpor/ Hibernation during extended periods of

energy deprivation• Counter current exchange to reduce loss of heat• Shivering in the cold/ sweating when hot

Hibernation is long term torpor

Additional metabolism that would benecessary to stay active in winter

Actualmetabolism

Bodytemperature

Arousals

Outsidetemperature Burrow

temperatureJune August October December February April

Tem

pera

ture

(°C)

Met

abol

ic ra

te(k

cal p

er d

ay)

200

100

0

35

30

25

20

15

10

5

0

-5

-10

-15

Figure 40.22

• Torpor- Is a physiological state in which activity is low and metabolism decreases• The body cools to near freezing

temperatures• Shivering warms body for brief

intervals• Saves energy during winter when food

is not available

Circulation and Gas Exchange- a model of specialization, coordination, and adaptation

• Animals have specialized organs and organ systems for gas exchange and circulation• The respiratory and circulatory systems reflect common ancestry and

divergence due to different environments. • Interaction and coordination between circulatory and respiratory systems

allow the organism obtain nutrients and eliminate wastes

Circulatory systems in animals• Gastrovascular cavity- open with the water• Open circulatory systems in insects- fluid bathes internal organs and

tissues• Closed circulatory systems- blood is circulated, materials exchange by

diffusion

Figure 42.2

Circularcanal

Radial canalMouth

Heart

Hemolymph in sinusessurrounding ograns

Anterior vessel

Tubular heart

Lateral vessels

Ostia

(a) An open circulatory systemFigure 42.3a

Interstitialfluid

Heart

Small branch vessels in each organ

Dorsal vessel(main heart)

Ventral vesselsAuxiliary hearts(b) A closed circulatory system

FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS

Systemic capillaries Systemic capillaries Systemic capillaries Systemic capillaries

Lung capillaries Lung capillariesLung and skin capillariesGill capillaries

Right Left Right Left Right Left Systemic

circuitSystemic

circuit

Pulmocutaneouscircuit

Pulmonarycircuit

Pulmonarycircuit

SystemiccirculationVein

Atrium (A)

Heart:ventricle (V)

Artery Gillcirculation

A

V VV VV

A A A AALeft Systemicaorta

Right systemicaorta

Figure 42.4

Vertebrate Circulatory Systems: Common Ancestry and Divergence in different environments

Homeostatic Mechanisms represent common ancestry and divergence in different environments

• The heart is just one example of a structure that has diverged in organisms

Here is a phylogeny based on a heart structure.

• Source: Emergence of Xin Demarcates a Key Innovation in Heart Evolution. DOI: 10.1371/journal.pone.0002857

Gas exchange systems all have large surface areas to maximize diffusion

Figure 42.20b

Gills in marine worms Salmon Gills Alveoli in Lungs

Interaction and coordination between circulatory and respiratory systems allow the organism obtain nutrients and eliminate wastes

Countercurrent exchange!!!

Figure 42.21

Gill arch

Water flow

Gillfilaments

Oxygen-poorblood

Oxygen-richblood

Water flowover lamellaeshowing % O2

Blood flowthrough capillariesin lamellaeshowing % O2

Lamella

100%

40%

70%

15%

90%

60% 30

% 5%

O2

Mammalian Respiratory Systems

Branch from the pulmonary vein

(oxygen-rich blood)

Branch from thepulmonary artery(oxygen-poor blood)

Alveoli

Colorized SEMSEM

50 µ

m

50 µ

mHeart