40 animalform&function text

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

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 40Chapter 40

Basic Principles of Animal Form and Function


• Overview: Diverse Forms, Common Challenges

• Animals inhabit almost every part of the biosphere

• Despite their amazing diversity

– All animals face a similar set of problems, including how to nourish themselves


• The comparative study of animals

– Reveals that form and function are closely correlated

Figure 40.1


• Natural selection can fit structure, anatomy, to function, physiology

– By selecting, over many generations, what works best among the available variations in a population


• Concept 40.1: Physical laws and the environment constrain animal size and shape

• Physical laws and the need to exchange materials with the environment

– Place certain limits on the range of animal forms


Physical Laws and Animal Form

• The ability to perform certain actions

– Depends on an animal’s shape and size


• Evolutionary convergence

– Reflects different species’ independent adaptation to a similar environmental challenge

Figure 40.2a–e

(a) Tuna

(b) Shark

(c) Penguin

(d) Dolphin

(e) Seal


Exchange with the Environment

• An 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


• A single-celled protist living in water

– Has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm

Figure 40.3a

Diffusion

(a) Single cell


• Multicellular organisms with a sac body plan

– Have body walls that are only two cells thick, facilitating diffusion of materials

Figure 40.3b

Mouth

Gastrovascularcavity

Diffusion

Diffusion

(b) Two cell layers


• Organisms with more complex body plans

– Have highly folded internal surfaces specialized for exchanging materials


External environment

Food CO2 O2Mouth

Animalbody

Respiratorysystem

Circulatorysystem

Nutrients

Excretorysystem

Digestivesystem

Heart

Blood

Cells

Interstitialfluid

Anus

Unabsorbedmatter (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


• Concept 40.2: Animal form and function are correlated at all levels of organization

• Animals are composed of cells

• Groups of cells with a common structure and function

– Make up tissues

• Different tissues make up organs

– Which together make up organ systems


• 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


Epithelial Tissue

• Epithelial tissue

– Covers the outside of the body and lines organs and cavities within the body

– Contains cells that are closely joined


• 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 simplecolumnar epithelium

A pseudostratifiedciliated columnarepithelium

Stratified squamous epithelia

Simple squamous epitheliaCuboidal epithelia

Basement membrane

40 µm

Figure 40.5


Connective Tissue

• Connective tissue

– Functions mainly to bind and support other tissues

– Contains sparsely packed cells scattered throughout an extracellular matrix


CollagenousfiberElasticfiber

Chondrocytes

Chondroitinsulfate

Loose connective tissue

Fibrous connective tissue

100

µm

100 µm

Nuclei

30 µm

Bone Blood

Centralcanal

Osteon

700 µm 55 µm

Red blood cellsWhite blood cell

Plasma

Cartilage

Adipose tissue

Fat droplets

150

µm

CONNECTIVE TISSUE

• Connective tissue

Figure 40.5


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


Nervous Tissue

• Nervous tissue

– Senses stimuli and transmits signals throughout the animal


• Muscle and nervous tissueMUSCLE TISSUE

Skeletal muscle100 µm

Multiplenuclei

Muscle fiber

Sarcomere

Cardiac muscle

Nucleus Intercalateddisk

50 µm

Smooth muscle Nucleus

Musclefibers

25 µm

NERVOUS TISSUE

Neurons Process

Cell body

Nucleus

50 µm

Figure 40.5


Organs and Organ Systems

• In all but the simplest animals

– Different tissues are organized into organs


Lumen ofstomach

Mucosa. The mucosa is anepithelial layer that linesthe lumen.

Submucosa. The submucosa isa matrix of connective tissuethat contains blood vesselsand nerves.

Muscularis. The muscularis consistsmainly of smooth muscle tissue.

0.2 mm

Serosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue.

• In some organs

– The tissues are arranged in layers

Figure 40.6


• Representing a level of organization higher than organs

– Organ systems carry out the major body functions of most animals


• Organ systems in mammals

Table 40.1


• Concept 40.3: 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


• The flow of energy through an animal, its bioenergetics

– Ultimately limits the animal’s behavior, growth, and reproduction

– Determines how much food it needs

• Studying an animal’s bioenergetics

– Tells us a great deal about the animal’s adaptations

Bioenergetics


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


• After the energetic needs of staying alive are met

– Any remaining molecules from food can be used in biosynthesis

Figure 40.7

Organic moleculesin food

Digestion andabsorption

Nutrient moleculesin body cells

Cellularrespiration

Biosynthesis:growth,

storage, andreproduction

Cellularwork

Heat

Energylost infeces

Energylost inurine

Heat

Heat

Externalenvironment

Animalbody

Heat

Carbonskeletons

ATP


• 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


• One way to measure metabolic rate

– Is to determine the amount of oxygen consumed or carbon dioxide produced by an organism

Figure 40.8a, b

This photograph shows a ghost crab in arespirometer. Temperature is held constant in thechamber, with air of known O2 concentration flow-ing through. The crab’s metabolic rate is calculatedfrom the difference between the amount of O2

entering and the amount of O2 leaving therespirometer. This crab is on a treadmill, runningat a constant speed as measurements are made.

(a)

(b) Similarly, the metabolic rate of a manfitted with a breathing apparatus isbeing monitored while he works outon a stationary bike.


• An animal’s metabolic rate

– Is closely related to its bioenergetic strategy

Bioenergetic Strategies


• Birds and mammals are mainly endothermic, meaning that

– Their bodies are warmed mostly by heat generated by metabolism

– They typically have higher metabolic rates


Stem Elongation

• Amphibians and reptiles other than birds are ectothermic, meaning that

– They gain their heat mostly from external sources

– They have lower metabolic rates


• The metabolic rates of animals

– Are affected by many factors

Influences on Metabolic Rate


Size and Metabolic Rate

• Metabolic rate per gram

– Is inversely related to body size among similar animals


• 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


• In general, an animal’s maximum possible metabolic rate

– Is inversely related to the duration of the activity

Figure 40.9

Max

imum

met

abol

ic r

ate

(kca

l/min

; log

sca

le)

500

100

50

10

5

1

0.5

0.1

A H

A H

A

AA

HH

H

A = 60-kg alligator

H = 60-kg human

1second

1minute

1hour

Time interval

1day

1week

Key

Existing intracellular ATP

ATP from glycolysis

ATP from aerobic respiration


• Different species of animals

– Use the energy and materials in food in different ways, depending on their environment

Energy Budgets


• An animal’s use of energy

– Is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction

Endotherms Ectotherm

Ann

ual e

nerg

y ex

pend

iture

(kc

al/y

r)

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

Ene

rgy

expe

nditu

re p

er u

nit

mas

s (k

cal/k

g•da

y)

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


• Concept 40.4: Animals regulate their internal environment within relatively narrow limits

• 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


• Regulating and conforming

– Are two extremes in how animals cope with environmental fluctuations

Regulating and Conforming


• 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


• Mechanisms of homeostasis

– Moderate changes in the internal environment

Mechanisms of Homeostasis


• A homeostatic control system has three functional components

– A receptor, a control center, and an effector

Figure 40.11

Response

No heatproduced

Roomtemperaturedecreases

Heaterturnedoff

Set point

Toohot

Setpoint

Control center:thermostat

Roomtemperatureincreases

Heaterturnedon

Toocold

Response

Heatproduced

Setpoint


• Most homeostatic control systems function by negative feedback

– Where buildup of the end product of the system shuts the system off


• A second type of homeostatic control system is positive feedback

– Which involves a change in some variable that triggers mechanisms that amplify the change


• Concept 40.5: 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


• Ectotherms

– Include most invertebrates, fishes, amphibians, and non-bird reptiles

• Endotherms

– Include birds and mammals

Ectotherms and Endotherms


• In general, ectotherms

– Tolerate greater variation in internal temperature than endotherms

Figure 40.12

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)

Bod

y te

mpe

ratu

re (

°C)

40

30

20

10

10 20 30 400


• 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


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 aliquid 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.

Figure 40.13


Balancing Heat Loss and Gain

• Thermoregulation involves physiological and behavioral adjustments

– That balance heat gain and loss


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


Hair

Sweatpore

Muscle

Nerve

Sweatgland

Oil glandHair follicle

Blood vessels

Adipose tissue

Hypodermis

Dermis

Epidermis

• In mammals, the integumentary system

– Acts as insulating material

Figure 40.14


• Many endotherms and some ectotherms

– Can alter the amount of blood flowing between the body core and the skin

Circulatory Adaptations


• In vasodilation

– Blood flow in the skin increases, facilitating heat loss

• In vasoconstriction

– Blood flow in the skin decreases, lowering heat loss


• 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 issurrounded by several veins in acountercurrent arrangement, allowingefficient heat exchange between arterialand venous blood.

Canadagoose

Artery Vein

35°C

Blood flow

VeinArtery

30º

20º

10º

33°

27º

18º

9º

Pacific bottlenose dolphin

2

1

3

2

3

Arteries carrying warm blood down thelegs of a goose or the flippers of a dolphinare in close contact with veins conveyingcool blood in the opposite direction, backtoward the trunk of the body. Thisarrangement facilitates heat transferfrom arteries to veins (blackarrows) along the entire lengthof the blood vessels.

1

Near the end of the leg or flipper, wherearterial blood has been cooled to far below the animal’s core temperature, the artery can still transfer heat to the even colderblood of an adjacent vein. The venous bloodcontinues 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 partsimmersed in cold water.

3

Figure 40.15

1 3


• Some specialized bony fishes and sharks

– Also possess countercurrent heat exchangers

Figure 40.16a, b

21º25º 23º

27º

29º31º

Body cavity

SkinArtery

Vein

Capillarynetwork withinmuscle

Dorsal aortaArtery andvein underthe skin

Heart

Bloodvesselsin gills

(a) Bluefin tuna. Unlike most fishes, the bluefin tuna maintainstemperatures in its main swimming muscles that are much higherthan the surrounding water (colors indicate swimming muscles cutin transverse section). These temperatures were recorded for a tunain 19°C water.

(b) Great white shark. Like the bluefin tuna, the great white sharkhas a countercurrent heat exchanger in its swimming muscles thatreduces the loss of metabolic heat. All bony fishes and sharks loseheat to the surrounding water when their blood passes through thegills. 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 gillsis conveyed via large arteries just under the skin, keeping cool bloodaway from the body core. As shown in the enlargement, smallarteries carrying cool blood inward from the large arteries under theskin are paralleled by small veins carrying warm blood outward fromthe inner body. This countercurrent flow retains heat in the muscles.


• Many endothermic insects

– Have countercurrent heat exchangers that help maintain a high temperature in the thorax

Figure 40.17


Cooling by Evaporative Heat Loss

• Many types of animals

– Lose heat through the evaporation of water in sweat

– Use panting to cool their bodies


• Bathing moistens the skin

– Which helps to cool an animal down

Figure 40.18


• Both endotherms and ectotherms

– Use a variety of behavioral responses to control body temperature

Behavioral Responses


• Some terrestrial invertebrates

– Have certain postures that enable them to minimize or maximize their absorption of heat from the sun

Figure 40.19


Adjusting Metabolic Heat Production

• Some animals can regulate body temperature

– By adjusting their rate of metabolic heat production


• Many species of flying insects

– Use shivering to warm up before taking flight

Figure 40.20

PREFLIGHT PREFLIGHTWARMUP

FLIGHT

Thorax

Abdomen

Tem

per

atur

e (°

C)

Time from onset of warmup (min)

40

35

30

25

0 2 4


• Mammals regulate their body temperature

– By a complex negative feedback system that involves several organ systems

Feedback Mechanisms in Thermoregulation


• In humans, a specific part of the brain, the hypothalamus

– Contains a group of nerve cells that function as a thermostat

Thermostat inhypothalamusactivates coolingmechanisms.

Sweat glands secrete sweat that evaporates, cooling the body.

Blood vesselsin skin dilate:capillaries fillwith warm blood;heat radiates fromskin surface. Body temperature

decreases;thermostat

shuts off coolingmechanisms.

Increased bodytemperature (suchas when exercising

or in hotsurroundings)

Homeostasis:Internal body temperatureof approximately 36–38C

Body temperatureincreases;thermostat

shuts off warmingmechanisms.

Decreased bodytemperature

(such as whenin cold

surroundings)

Blood vessels in skinconstrict, diverting bloodfrom skin to deeper tissuesand reducing heat lossfrom skin surface.

Skeletal muscles rapidlycontract, causing shivering,which generates heat.

Thermostat inhypothalamusactivateswarmingmechanisms.Figure 40.21


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


• Acclimatization may involve cellular adjustments

– Or in the case of birds and mammals, adjustments of insulation and metabolic heat production


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


• 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 benecessary to stay active in winter

Actualmetabolism

Bodytemperature

Arousals

Outsidetemperature Burrow

temperature

June August October December February April

Tem

pera

ture

(°C

)M

etab

olic

rat

e(k

cal p

er d

ay)

200

100

0

35

30

25

20

15

10

5

0

-5

-10

-15

Figure 40.22


• 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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40 animalform&function text