d. lopez louie

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Mark Louie D. Lopez

Department of Biology

College of Science

Polytechnic University of the Philippines

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OUTLINE

• Overview: Diverse Forms, Common

Challenges

• Animals inhabit almost every part of the

biosphere

• All animals face a similar set of problems,

including how to nourish themselves

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FORM AND FUNCTION RELATION

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SELECTION OF FORMS FIT TO FUNCTION

FORM : FUNCTIONN

atu

ral S

ele

ctio

n

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PHYSICAL LAWS IN FORM AND FUNCTION

Physical laws and the need to

exchange materials with the

environment place certain limits on

the range of animal forms

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EVOLUTIONARY CONVERGENCE

Reflects different species’

independent adaptation to

a similar environmental

challenge

(a) Tuna

(b) Shark

(c) Penguin

(d) Dolphin

(e) Seal

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EXCHANGE WITH THE ENVIRONMENT

• Animal’s size and shape have a direct effect

on how the animal exchanges energy and

materials with its surroundings

• Exchange with the environment occurs as

substances dissolved in the aqueous

medium diffuse and are transported across the

cells’ plasma membranes

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• A single-celled protist living in water has a

sufficient surface area of plasma membrane

to service its entire volume of cytoplasm

EXCHANGE OF MATERIAL IN PROKARYOTE

Diffusion

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EXCHANGE OF MATERIAL IN EUKARYOTE

• Multicellular organisms with a sac body plan have

body walls that are only two cells thick, facilitating

diffusion of materials

Mouth

Gastrovascular

cavity

Diffusion

Diffusion

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• Organisms with more complex body plans have

highly folded internal surfaces specialized for

exchanging materials

EXCHANGE OF MATERIAL IN COMPLEX FORM

Respiratory

system

Circulatory

system

Excretory

system

Digestive

system

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LEVELS OF ORGANIZATIONAL STRUCTURE

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• Different types of tissues

– Have different structures that are suited to their

functions

• Tissues are classified into four main

categories

– Epithelial, connective, muscle, and nervous

TISSUE STRUCTURE AND FUNCTION

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EPITHELIAL TISSUE

• Epithelial tissue

– Covers the outside of the body and lines

organs and cavities within the body

– Contains cells that are closely joined

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EPITHELIAL TISSUE

EPITHELIAL TISSUE

Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often

located where secretion or active absorption of substances is an important function.

A stratified columnar

epithelium

A simple

columnar

epithelium

A pseudostratified

ciliated columnar

epithelium

Stratified squamous epithelia

Simple squamous epithelia

Cuboidal epithelia

Basement membrane

40 µm

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CONNECTIVE TISSUE

• Connective tissue

– Functions mainly to bind and support other

tissues

– Contains sparsely packed cells scattered

throughout an extracellular matrix

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CONNECTIVE TISSUE

Collagenous

fiber

Elastic

fiber

Chondrocytes

Chondroitin

sulfate

Loose connective tissue

Fibrous connective tissue

100 µ

m

100 µm

Nuclei

30 µm

Bone Blood

Central

canal

Osteon

700 µm 55 µm

Red blood cells

White blood cell

Plasma

Cartilage

Adipose tissue

Fat droplets

150 µ

m

CONNECTIVE TISSUE

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MUSCLE TISSUE

• Muscle tissue

– Is composed of long cells called muscle fibers

capable of contracting in response to nerve

signals

– Is divided in the vertebrate body into three

types: skeletal, cardiac, and smooth

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NERVOUS TISSUE

• Nervous tissue

– Senses stimuli and transmits signals

throughout the animal

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MUSCLE AND NERVOUS TISSUE

MUSCLE TISSUESkeletal muscle

100 µm

Multiple

nuclei

Muscle fiber

Sarcomere

Cardiac muscle

Nucleus Intercalated

disk

50 µm

Smooth muscle Nucleus

Muscle

fibers

25 µm

NERVOUS TISSUE

Neurons Process

Cell body

Nucleus

50 µm

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ORGANS AND ORGAN SYSTEMS

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Lumen of

stomach

Mucosa. The mucosa is an

epithelial layer that lines

the lumen.

Submucosa. The submucosa is

a matrix of connective tissue

that contains blood vessels

and nerves.

Muscularis. The muscularis consists

mainly of smooth muscle tissue.

0.2 mm

Serosa. External to the muscularis is the serosa,

a thin layer of connective and epithelial tissue.

TISSUES ORGANIZED TO FORM ORGANS

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ORGAN SYSTEMS

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• Animals use the chemical energy in food to

sustain form and function

• All organisms require chemical energy for

growth, repair, physiological processes,

regulation, and reproduction

ENERGY FOR FORM AND FUNCTION

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• The flow of energy through an animal, its

bioenergetics

– Ultimately limits the animal’s behavior, growth,

and reproduction

– Determines how much food it needs

BIOENERGETICS

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ENERGY SOURCES AND ALLOCATION

• Animals harvest chemical energy

– From the food they eat

• Once food has been digested, the energy-

containing molecules

– Are usually used to make ATP, which powers

cellular work

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• After the energetic needs of staying alive are

met, any remaining molecules from food can be

used in biosynthesis

ENERGY FOR BIOMOLECULE PRODUCTION

Organic molecules

in food

Digestion and

absorption

Nutrient molecules

in body cells

Cellular

respiration

Biosynthesis:

growth,

storage, and

reproductionCellular

work

Heat

Energy

lost in

feces

Energy

lost in

urine

Heat

Heat

External

environment

Animal

body

Heat

Carbon

skeletons

ATP

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• An animal’s metabolic rate

– Is the amount of energy an animal uses in a

unit of time

– Can be measured in a variety of ways

QUANTIFYING ENERGY USE

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METABOLIC RATE

• One way to measure metabolic rate is to

determine the amount of oxygen consumed or

carbon dioxide produced by an organism

This photograph shows a ghost crab in a

respirometer. Temperature is held constant in the

chamber, with air of known O2 concentration flow-

ing through. The crab’s metabolic rate is calculated

from the difference between the amount of O2

entering and the amount of O2 leaving the

respirometer. This crab is on a treadmill, running

at a constant speed as measurements are made.

(a)

(b) Similarly, the metabolic rate of a man

fitted with a breathing apparatus is

being monitored while he works out

on a stationary bike.

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• An animal’s metabolic rate is closely related

to its bioenergetic strategy

BIOENERGETIC STRATEGIES

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• Birds and mammals are mainly endothermic,

meaning that

– Their bodies are warmed mostly by heat

generated by metabolism

– They typically have higher metabolic rates

ENDOTHERMIC ORGANISMS

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ECTOTHERMIC ORGANISMS

• Amphibians and reptiles other than birds are

ectothermic, meaning that

– They gain their heat mostly from external

sources

– They have lower metabolic rates

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SIZE AND METABOLIC RATE

• Metabolic rate per gram is inversely related to

body size among similar animals

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• The basal metabolic rate (BMR)

– Is the metabolic rate of an endotherm at rest

• The standard metabolic rate (SMR)

– Is the metabolic rate of an ectotherm at rest

• For both endotherms and ectotherms

– Activity has a large effect on metabolic rate

ACTIVITY AND METABOLIC RATE

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• In general, an animal’s maximum possible

metabolic rate is inversely related to the

duration of the activity

Maxim

um

meta

bolic

rate

(kcal/m

in; lo

g s

cale

)

500

100

50

10

5

1

0.5

0.1

A H

AH

A

AA

HH

H

A = 60-kg alligator

H = 60-kg human

1

second

1

minute1

hourTime interval

1

day

1

week

Key

Existing intracellular ATP

ATP from glycolysis

ATP from aerobic respiration

METABOLIC RATE AND ACTIVITY DURATION

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• Different species of animals

– Use the energy and materials in food in

different ways, depending on their

environment

ENERGY BUDGETS

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• An animal’s use of energy is partitioned to

BMR (or SMR), activity, homeostasis,

growth, and reproduction

ENERGY UTILIZATION

Endotherms Ectotherm

Annual energ

y e

xpenditure

(kcal/yr)

800,000 Basal

metabolic

rate

ReproductionTemperature

regulation costs

Growth

Activity

costs

60-kg female human

from temperate climate

Total annual energy expenditures(a)

340,000

4-kg male Adélie penguin

from Antarctica (brooding)

4,000

0.025-kg female deer mouse

from temperate

North America

8,000

4-kg female python

from Australia

Energ

y e

xpenditure

per

unit m

ass

(kcal/kg•d

ay)

438

Deer mouse

233

Adélie penguin

36.5

Human

5.5

Python

Energy expenditures per unit mass (kcal/kg•day)(b)

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HOMEOSTASIS

• The internal environment of vertebrates

– Is called the interstitial fluid, and is very

different from the external environment

• Homeostasis is a balance between external

changes

– And the animal’s internal control mechanisms

that oppose the changes

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• Regulating and conforming

– Are two extremes in how animals cope with

environmental fluctuations

REGULATING AND CONFORMING

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• An animal is said to be a regulator

– If it uses internal control mechanisms to

moderate internal change in the face of

external, environmental fluctuation

• An animal is said to be a conformer

– If it allows its internal condition to vary with

certain external changes

REGULATING AND CONFORMING

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• Mechanisms of homeostasis

– Moderate changes in the internal environment

MECHANISMS OF HOMEOSTASIS

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MECHANISMS OF HOMEOSTASIS

• A homeostatic control system has three

functional components

Response

No heat

produced

Room

temperature

decreases

Heater

turned

off

Set point

Too

hot

Set

point

Control center:

thermostat

Room

temperature

increases

Heater

turned

on

Too

cold

Response

Heat

produced

Set

point

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NEGATIVE FEEDBACK

• Most homeostatic control systems function by

negative feedback

– Where buildup of the end product of the

system shuts the system off

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POSITIVE FEEDBACK

• A second type of homeostatic control system is

positive feedback

– Which involves a change in some variable that

triggers mechanisms that amplify the change

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THERMOREGULATION

• Thermoregulation contributes to homeostasis

and involves anatomy, physiology, and

behavior

• Thermoregulation

– Is the process by which animals maintain an

internal temperature within a tolerable range

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• Ectotherms

– Include most invertebrates, fishes, amphibians,

and non-bird reptiles

• Endotherms

– Include birds and mammals

ECTOTHERMS AND ENDOTHERMS

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• In general, ectotherms

– Tolerate greater variation in internal temperature

than endotherms

ECTOTHERMS

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)

Bo

dy t

em

pe

ratu

re (

°C)

40

30

20

10

10 20 30 400

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• Endothermy is more energetically expensive

than ectothermy

– But buffers animals’ internal temperatures

against external fluctuations

– And enables the animals to maintain a high

level of aerobic metabolism

ENDOTHERMS

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MODES OF HEAT EXCHANGE

• Organisms exchange heat by four physical processes

Radiation is the emission of electromagnetic

waves by all objects warmer than absolute

zero. Radiation can transfer heat between

objects that are not in direct contact, as when

a lizard absorbs heat radiating from the sun.

Evaporation is the removal of heat from the surface of a

liquid that is losing some of its molecules as gas.

Evaporation of water from a lizard’s moist surfaces that

are exposed to the environment has a strong cooling effect.

Convection is the transfer of heat by the

movement of air or liquid past a surface,

as when a breeze contributes to heat loss

from a lizard’s dry skin, or blood moves

heat from the body core to the extremities.

Conduction is the direct transfer of thermal motion (heat)

between molecules of objects in direct contact with each

other, as when a lizard sits on a hot rock.

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BALANCING HEAT LOSS AND GAIN

• Thermoregulation involves physiological and

behavioral adjustments

– That balance heat gain and loss

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INSULATION

• Insulation, which is a major thermoregulatory

adaptation in mammals and birds

– Reduces the flow of heat between an animal

and its environment

– May include feathers, fur, or blubber

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INSULATION IN MAMMALS

Hair

Sweatpore

Muscle

Nerve

Sweat

gland

Oil gland

Hair follicle

Blood vessels

Adipose tissue

Hypodermis

Dermis

Epidermis

• In mammals, the integumentary system acts

as insulating material

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• Many endotherms and some ectotherms

– Can alter the amount of blood flowing between

the body core and the skin

CIRCULATORY ADAPTATIONS

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• In vasodilation

– Blood flow in the skin increases, facilitating

heat loss

• In vasoconstriction

– Blood flow in the skin decreases, lowering heat

loss


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• Many marine mammals and birds have arrangements of

blood vessels called countercurrent heat exchangers

that are important for reducing heat loss


In the flippers of a dolphin, each artery is

surrounded by several veins in a

countercurrent arrangement, allowing

efficient heat exchange between arterial

and venous blood.

Canada

goose

Artery Vein

35°C

Blood flow

Vein

Artery

30º

20º

10º

33°

27º

18º

9º

Pacific

bottlenose

dolphin

2

1

3

2

3

Arteries carrying warm blood down the

legs of a goose or the flippers of a dolphin

are in close contact with veins conveying

cool blood in the opposite direction, back

toward the trunk of the body. This

arrangement facilitates heat transfer

from arteries to veins (black

arrows) along the entire length

of the blood vessels.

1

Near the end of the leg or flipper, where

arterial blood has been cooled to far below

the animal’s core temperature, the artery

can still transfer heat to the even colder

blood of an adjacent vein. The venous blood

continues to absorb heat as it passes warmer

and warmer arterial blood traveling in the

opposite direction.

2

As the venous blood approaches the

center of the body, it is almost as warm

as the body core, minimizing the heat lost

as a result of supplying blood to body parts

immersed in cold water.

3

1 3

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COUNTERCURRENT HEAT EXCHANGERS

• Some specialized bony fishes and sharks

– Also possess countercurrent heat exchangers

21º25º 23º

27º

29º31º

Body cavity

Skin

Artery

Vein

Capillary

network within

muscle

Dorsal aorta

Artery and

vein under

the skin

Heart

Blood

vessels

in gills

(a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintains

temperatures in its main swimming muscles that are much higher

than the surrounding water (colors indicate swimming muscles cut

in transverse section). These temperatures were recorded for a tuna

in 19°C water.

(b) Great white shark. Like the bluefin tuna, the great white shark

has a countercurrent heat exchanger in its swimming muscles that

reduces the loss of metabolic heat. All bony fishes and sharks lose

heat to the surrounding water when their blood passes through the

gills. However, endothermic sharks have a small dorsal aorta,

and as a result, relatively little cold blood from the gills goes directly

to the core of the body. Instead, most of the blood leaving the gills

is conveyed via large arteries just under the skin, keeping cool blood

away from the body core. As shown in the enlargement, small

arteries carrying cool blood inward from the large arteries under the

skin are paralleled by small veins carrying warm blood outward from

the inner body. This countercurrent flow retains heat in the muscles.

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COUNTERCURRENT HEAT EXCHANGERS

• Many endothermic insects

– Have countercurrent heat exchangers that help

maintain a high temperature in the thorax

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COOLING BY EVAPORATIVE HEAT LOSS

• Many types of animals

– Lose heat through the evaporation of water in

sweat

– Use panting to cool their bodies

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• Bathing moistens the skin which helps to cool

an animal down

BEHAVIORAL RESPONSES

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• Both endotherms and ectotherms

– Use a variety of behavioral responses to

control body temperature


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• Some terrestrial invertebrates have certain

postures that enable them to minimize or

maximize their absorption of heat from the sun

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ADJUSTING METABOLIC HEAT PRODUCTION

• Some animals can regulate body temperature

– By adjusting their rate of metabolic heat

production

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• Many species of flying insects use shivering to

warm up before taking flight

ADJUSTING METABOLIC HEAT PRODUCTION

PREFLIGHT PREFLIGHT

WARMUPFLIGHT

Thorax

Abdomen

Te

mp

era

ture

(°C

)

Time from onset of warmup (min)

40

35

30

25

0 2 4

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• Mammals regulate their body temperature

– By a complex negative feedback system that

involves several organ systems

FEEDBACK MECHANISMS IN THERMOREGULATION

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• In humans, a specific part of

the brain, the hypothalamus

– Contains a group of nerve

cells that function as

a thermostat

FEEDBACK MECHANISMS IN THERMOREGULATION

Thermostat in

hypothalamus

activates cooling

mechanisms.

Sweat glands secrete

sweat that evaporates,

cooling the body.

Blood vessels

in skin dilate:

capillaries fill

with warm blood;

heat radiates from

skin surface. Body temperature

decreases;

thermostat

shuts off cooling

mechanisms.

Increased body

temperature (such

as when exercising

or in hot

surroundings)

Homeostasis:

Internal body temperature

of approximately 36–38C

Body temperature

increases;

thermostat

shuts off warming

mechanisms.

Decreased body

temperature

(such as when

in cold

surroundings)

Blood vessels in skin

constrict, diverting blood

from skin to deeper tissues

and reducing heat loss

from skin surface.

Skeletal muscles rapidly

contract, causing shivering,

which generates heat.

Thermostat in

hypothalamus

activates

warming

mechanisms.

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ADJUSTMENT TO CHANGING TEMPERATURES

• In a process known as acclimatization

– Many animals can adjust to a new range of

environmental temperatures over a period of

days or weeks

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ADJUSTMENT TO CHANGING TEMPERATURES

• Acclimatization may involve cellular

adjustments

– Or in the case of birds and mammals,

adjustments of insulation and metabolic heat

production

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TORPOR AND ENERGY CONSERVATION

• Torpor

– Is an adaptation that enables animals to save

energy while avoiding difficult and dangerous

conditions

– Is a physiological state in which activity is low

and metabolism decreases

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• Hibernation is long-term torpor

– That is an adaptation to winter cold and food scarcity during which the animal’s body temperature declines


Additional metabolism that would be

necessary to stay active in winter

Actual

metabolism

Body

temperature

Arousals

Outside

temperature Burrow

temperature

June August October December February April

Tem

pera

ture

(°C

)M

eta

bolic

rate

(kcal per

day)

200

100

0

35

30

25

20

15

10

5

0

-5

-10

-15

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• Estivation, or summer torpor

– Enables animals to survive long periods of

high temperatures and scarce water supplies

• Daily torpor

– Is exhibited by many small mammals and birds

and seems to be adapted to their feeding

patterns

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END

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d. lopez louie

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